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Laboratory investigation of RAP for various layers of flexible and concrete pavement
International Journal of Pavement Engineering
Abstract
The present study investigates the potential of RAP for various layers of flexible and concrete pavements. Natural aggregates were replaced in different proportions by the coarse RAP and fine RAP, for preparations of granular subbase, wet mix Macadam, dry lean concrete, dense bituminous Macadam and Plain concrete mixes. Utilisation of both fractions of RAP resulted in reductions in the optimum moisture content (OMC) and maximum dry density of granular subbase and wet mix Macadam mixes, whereas, incorporation of the same was found to increase the OMC of dry lean concrete mixes. Incorporation of coarse RAP doesn’t affect much the engineering properties of base and subbase layers in comparison to fine RAP. Improving the gradation of fine RAP was found to increase its suitability in all the considered mixes. Similarly, utilisation of coarse RAP was found to improve the workability of concrete mixes, however, significant reductions in strength properties were noted. It was observed that as the strength requirement of layer increases, the negative impact of RAP on strength properties also increases linearly, suggesting incorporating a higher fraction of RAP in lower layers and a lower usage of the same for wearing course of the pavement.
... Furthermore, RAP aggregate utilisation for the construction of new PC pavements will escalate the vision of sustainability [11,12]. The ban imposed by government agencies on the extraction of conventional natural aggregates through quarrying activities has led to the concept of the use of RAP as much as possible for different construction purposes [13][14][15][16]. Also, various problems such as disposal of RAP, costs associated with the transportation of natural aggregates and release of greenhouse gases in the environment could be solved with the effective on-spot use of RAP aggregates in constructing new pavements [14,[17][18][19][20][21][22][23][24]. ...
... The ban imposed by government agencies on the extraction of conventional natural aggregates through quarrying activities has led to the concept of the use of RAP as much as possible for different construction purposes [13][14][15][16]. Also, various problems such as disposal of RAP, costs associated with the transportation of natural aggregates and release of greenhouse gases in the environment could be solved with the effective on-spot use of RAP aggregates in constructing new pavements [14,[17][18][19][20][21][22][23][24]. Recently, the use of RAP aggregate for the construction of concrete pavements has received much attention worldwide. ...
... As regards the porosity of the considered RAP-PC pavement mixes, it increased by 17 on 5% BGA inclusion and then decreased by 3 and 6% on further inclusions of BGA in proportions of 10 and 15%, respectively, at 28 days of water curing age. The increase in porosity on BGA inclusion could be possibly due to the hygroscopic nature of BGA particles which absorbs more water and exhibit a weak ITZ, resulting in poor bonding between RAP aggregates and cement paste [14,25] ...
The current study examines the strength and transport properties of reclaimed asphalt pavement (RAP) inclusive pervious concrete (PC) pavement mixes containing various industrial and agricultural wastes such as silica fume (SF), fly ash (FA), and bagasse ash (BGA). Apart from a conventional PC mix (containing natural aggregates) and a 100% RAP inclusive PC mix, seven different mixes were developed by mixing 100% RAP aggregates with SF (5 and 10%), FA (10 and 15%), and BGA (5, 10, and 15%) as partial replacements for ordinary Portland cement. The above-mentioned PC pavement mixes were investigated for density, porosity, permeability, compressive strength, modulus of rupture, and abrasion resistance. The interconnected pore structure of conventional PC and RAP-PC pavement mixes was investigated using 2D image analysis and X-Ray microcomputed tomography. Based on the laboratory results, it can be stated that the inclusion of RAP significantly improves the transport properties of PC pavement mixes with increased porosity and permeability values. This was primarily due to a more interconnected pore matrix and lesser isolated voids in the RAP-PC pavement mix. The addition of SF could only improve the strength parameters (compressive strength and modulus of rupture) of the RAP-PC pavement mix. In contrast, BGA inclusion was observed to improve its transport properties (porosity and permeability). Furthermore, the inclusion of SF, FA, and BGA in a 100% RAP-PC mix improved abrasion resistance. When compared to the conventional PC pavement mix, incorporating RAP aggregates blended with SF, FA, and BGA can reduce the production cost of 1 m3 PC by 30–61% and lower CO2 emissions by 13–21%. However, considering the strength and transport property requirements of PC mixes, as well as the economic and environmental viability, the present investigation recommends using 5% SF, 10% FA, and 10% BGA in a 100% RAP-PC pavement mix.
... Construction and maintenance activities of pavements such as repairing, resurfacing, patching, etc. require abundant quantities of aggregates and binder that are considered to be a non-renewable source of energy, but owing to a ban on quarrying activities and lack of natural resources, meeting of such enormous quantities of aggregates is difficult (Singh et. al., 2017;Singh et al., 2019b;Kumari et al., 2018;Singh et al., 2018;Debbarma et al., 2019;Singh and Ransinchung, 2018). On the other hand, waste such as fly ash, crumb rubber, steel fibers, jute, coir, and waste plastic may also be utilized for construction of pavements; however, the coarser fraction would again be missing. ...
... Low initial cost and 100% recyclability makes flexible pavement as a first choice among the road agencies over rigid pavements, however, due to a recent escalation in asphalt binder cost, researchers are in a constant search of alternative aggregates and binders, which can incur lower cost. Up to 90% of roads in India consist of flexible pavement and after the completion of its service life this pavement is reclaimed and disposed off in nearby dumping site or become a part of landfills (Hu et al., 2019;Kumari et al., 2018;Singh et al., 2019b;Singh et al., 2017;Debbarma et al., 2019). This waste generated as a result of reclamation of flexible pavements is termed as Reclaimed Asphalt Pavements (RAP). ...
... RAP comprises of about 95% re-usable aggregates and 5% asphalt binder and these could be re-used for the construction of new pavements, thereby, reducing the total construction cost and also leading to several environmental benefits such as reduced landfills and reduced carbon footprints (Kumari et al., 2018). As far as the aggregate properties are concerned, extracted RAP aggregates has shown comparable performance to that of the conventional ones, whereas, on the other hand, bitumen adhered around the RAP exhibited inferior properties (low penetration value, high softening point, and high viscosity etc.) in comparison to the conventional binder (Singh et al., 2019b;Kumari et al., 2019;Shen, et al., 2007;Bowers et al., 2014). Similarly, the RAP incorporation increases the strength, rutting resistance, although, the fatigue, cracking were found to have 396 JOURNAL OF SOLID WASTE TECHNOLOGY AND MANAGEMENT VOLUME 46, NO. 3 AUGUST 2020 reduced with RAP incorporation. ...
Date palm leaves are huge wastes in the growing regions which are mostly burnt annually. One of the solutions is converting leaves to substrate and using in soilless culture. In this study, 24 different mixes were produced by adding zeolite and vermicompost to the composted date palm substrate. The mixtures were incubated for 2 weeks in 35-40%(w/w) moisture. Their physicochemical properties were measured. To study the mixes, two multivariate methods were applied; Principal Component Analysis (PCA) to determine the factors that affect mixture properties to a large extent and Cluster Analysis (CLA). The clustering was processed based on the factors recognized by the PCA. The CLA was done in several stages and in each stage the furthest mixture from cocopeat was deleted. Date palm substrate was processed by leaf waste composting. Using the CLA, on the basis of the PCA analysis, the most superior mixture was defined as date palm substrate (90%), vermicompost(5%) and zeolite (5%) respectively (P 90 V 5 Z 5 ) with indexes in cation exchange capacity, particle density, total porosity, bulk density, water holding capacity and electrical conductivity in the same cluster as cocopeat.
... The utilization of solid waste materials collected from industry known as silica 76 fume (SF) or Nano-silica (NS) might greater enhance the mechanical and durability 77 properties of standard concrete significantly [40][41]. Henceforth, the utilization of 100% 78 RAP recycled aggregates is typically not advised due to their subpar performance when 79 it is compared to either natural coarse or fine aggregates in concrete mixes [42]. So, sev-80 eral researchers recommended 40-50% of replacement of RAP aggregates in concrete 81 mixes to achieve the benchmark of strength for the production of RAP concrete [37][38][39][40][41]. 82 With the considerations of statistical analysis, the mathematical modeling gives the high 83 86 found that the moisture content is less susceptible than the fine RAP percentages affect-87 ing the strength characteristics of dry lean concrete (DLC) mixes by Two-way analysis of 88 variance (ANOVA). ...
... The microstructure of concrete mixes signifies the visualization of the morphological 423 changes, pore structure, and interfacial transition zone (ITZ) between cement paste and 424 aggregates in pavement structures [74][75][76]. Past researchers recorded that the asphalt 425 content encircling RAP has been ascribed for the inferior bonding between RAP and 426 mortar matrix [77][78][79][80]. The two-way analysis of variance (ANOVA) normally scrutinizes the influence of two 444 independent variables on their outcome [81][82][83][84][85]. ...
Reclaimed Asphalt Pavement (RAP) as recycled aggregates is a relatively a new construction process of rigid pavements due to the scarcity and degradation of natural aggregates. This study aims at sequential characterization of RAP aggregate to obtain an optimized proportions for strength. For this purpose, RAP aggregates were used for replacement of natural aggregates (NA) in concrete mix which was achieved by varying from 0 -100% . Furthermore, zirconia silica fume (ZSF) were used as an partial replacement of the cement in the concrete mix, replacing Ordinary Portland Cement (OPC). Experimental studies have shown that the incorporation of washed RAP (WRAP) slightly reduces the compressive strength of concrete by 2.7- 37.35% as compare to the reference control concrete mix. Although the 7-days, 28-days and 56-days compressive strength of WRAP recycled aggregate based concrete are slightly better than 7-days, 28-days and 56-days compressive strength of dirty RAP (DRAP) recycled aggregate based concrete. Similar trend was observed in the flexural strength and split tensile strength of WRAP recycled aggregate based. Overall, the results show that 40% WRAP recycled aggregates with 10% ZSF as a replacement of cement outperform DRAP aggregates in concrete mixes. According to the ANOVA results, the combination of ZSF and WRAP aggregates met the cement concrete pavement strength standard, thereby contributing to sustainable development. Reclaimed Asphalt Concrete Pavements (RACP) are now seen as a potential and long-term answer to the present environmental and economic crisis.
... Plati and Cliati [51] reported that 100% RAP material and 50% RAP/50% virgin aggregate (VA) material produced M R results similar to those investigated for VA, particularly at increased compaction pressures. Others systematically agree that RAP addition to VA (i) reduces dry density [52], (ii) reduces bearing capacity (as measured by the California Bearing Ratio) [52], and (iii) increases the modulus of elasticity [47,[53][54][55]. However, the question usually arises as to how to utilize the high RAP amount in the base layer without diminishing the mechanical properties. ...
... Plati and Cliati [51] reported that 100% RAP material and 50% RAP/50% virgin aggregate (VA) material produced M R results similar to those investigated for VA, particularly at increased compaction pressures. Others systematically agree that RAP addition to VA (i) reduces dry density [52], (ii) reduces bearing capacity (as measured by the California Bearing Ratio) [52], and (iii) increases the modulus of elasticity [47,[53][54][55]. However, the question usually arises as to how to utilize the high RAP amount in the base layer without diminishing the mechanical properties. ...
The use of recycled asphalt pavement (RAP) materials in asphalt concrete pavements (ACP) brings significant cost and environmental benefits. In practice, however, the amount of RAP readily available far exceeds the amount being utilized in ACPs, which still leaves the problem of excess RAP in the environment partially solved. Additionally, ACPs containing RAP materials (i.e., RAP-ACPs) can still be landfilled after they have reached the end of their useful life, which may restore the original environmental waste problem. To address these, researchers have demonstrated different ways to maximize the application of RAP in ACPs. Among them, the use of RAP in pavement preventive maintenance (PPM) treatments and the repeated recycling of RAP-ACPs (i.e., RnAP) are specifically discussed in this review. It is envisaged that, by promoting these two practices, the application and benefits of RAP can be further maximized to improve sustainability. This review also discusses the long-term behavior of RAP-ACP, which is crucial to inspire confidence in the wider application of RAP in ACP. Studies on RAP-PPM have shown that virgin PPM treatments can successfully accommodate RAP materials by adjusting their mix design. So far, research on RnAP has been limited to how multiple-recycling affects the performance properties of the blends, showing improvements in rutting resistance and moisture susceptibility but little effect on linear viscoelasticity and cracking. Overall, the lack of sufficient research is considered to be the biggest challenge in facilitating the implementation of these two sustainable RAP technologies. Little or nothing is known about the bonding mechanisms between RAP and fresh PPM binders, the molecular and chemical changes in RnAP binders, or the functional performance characteristics, actual pavement performance, and long-term performance of both RAP-PPM and RnAP blends. An understanding of these aspects is very relevant to maximize and continue the beneficial reuse of RAP in ACPs while safeguarding human and environmental health.
... 5 Also, PCP has a range of pavement applications such as pathways in broad daylight parks, parking garages, hangars, transport yards/ports/terminals, base layers, and heavy low flow roads, etc. [6][7][8] Also, the use of reclaimed asphalt pavement (RAP) aggregates in the construction of new concrete roads will contribute to better sustainability principles. 9,10 As national government agencies prohibit mining/excavation of traditional natural aggregates 11,12 and use the lowest bidding rates of contractors, RAP will be a viable alternate option of natural aggregate in the coming years. 2 Even more, the use of RAP materials for modern pavement projects would reduce numerous problems such as issues of RAP recycling, overall transport expenses of aggregates, and excessive greenhouse gas emissions during construction. 1, 2,9,[13][14][15][16][17] The integration of recycled asphalt pavement into concrete roads has drawn the interest of scholars and industrialists around the world, but the use of RAP has been hindered due to its poor strength. ...
... 9,10 As national government agencies prohibit mining/excavation of traditional natural aggregates 11,12 and use the lowest bidding rates of contractors, RAP will be a viable alternate option of natural aggregate in the coming years. 2 Even more, the use of RAP materials for modern pavement projects would reduce numerous problems such as issues of RAP recycling, overall transport expenses of aggregates, and excessive greenhouse gas emissions during construction. 1, 2,9,[13][14][15][16][17] The integration of recycled asphalt pavement into concrete roads has drawn the interest of scholars and industrialists around the world, but the use of RAP has been hindered due to its poor strength. 2,11,14,[17][18][19][20][21][22][23][24] Furthermore, it is proposed that only 50 % of conventional natural aggregates be replaced with coarse RAP (cRAP). ...
Pervious concrete (PC) is a new type of concrete that is gaining popularity because of its low-impact development capabilities and ability to reduce stormwater runoff. The current study focuses on the potential use of waste from the sugarcane industry and on flexible pavement, specifically sugarcane bagasse ash (SBGA) and reclaimed asphalt pavement (RAP), to create PC mixes. Furthermore, an unconventional method was used to extract the benefits of RAP without compromising the structural integrity of PC: designing the mixture based on hydrological properties rather than mechanical parameters and then improving structural integrity through the use of SBGA without compromising the hydrological capacity of the designed PC mixture. Six PC mix combinations were developed by substituting recycled asphalt pavement for natural coarse aggregate in varying proportions of 0, 50, and 100 %. Following that, three RAP-incorporated PC mixes were created using 5, 10, and 15 % SBGA as a partial replacement for cement. It was discovered that using SBGA as a partial replacement for cement reduces mechanical properties while increasing functional properties such as permeability. Surprisingly, no significant differences were observed in the percentage voids of PC mixes containing RAP aggregates. The addition of 10 % SBGA significantly improves the mechanical properties of 100 % coarse RAP (cRAP)-inclusive PC mixes. When the total cost of 1 m3 concrete was calculated, the addition of cRAP aggregates and SBGA in pervious concrete pavements mixes resulted in a 44 % reduction. Furthermore, the current study suggests replacing 10 % of ordinary Portland cement with SBGA in cRAP inclusive PC mixes, as this increases the strength of cRAP–PC mixes while also providing environmental and economic benefits.
... The ITZ region is about 50 μm thick and is highly porous with low density, low calcium silicate hydrate (C-S-H), and larger calcium hydroxide (CH) and ettringites as compared to bulk mortar Roesler 2015b, 2016;Shi et al. 2017Shi et al. , 2020Singh et al. 2018b). Further, the ITZ of RAP concrete was found to be more porous than conventional concrete when determined through petrographic examination, which results in negative impact (Debbarma et al. 2020a;Singh et al. 2018dSingh et al. , 2019b. However, the CH crystallization was not found to have a higher negative impact as compared to conventional concrete due to its size and presence in the ITZ of the RAP concrete. ...
... It was seen that the inclusion of other supplementary cementitious materials particles in RAP-included concrete mixtures reduced the amount of CH crystals (Ashraf and Olek 2018;Debbarma et al. 2019a;Singh et al. 2018Singh et al. , 2019b. The presence of reactive SiO 2 in cement reacts with the hydrated crystals (CH) and results in the formation of additional hydrate phases of C-S-H gels during the pozzolanic reaction [Eq. ...
Pervious concrete is special class of concrete which has application in reducing storm
water runoff and mitigation of urban heat islands (UHI). This paper studied about the
morphological and pore structure characterization of pervious concrete (PC) mixes
when reclaimed asphalt pavement (RAP) aggregates is used as a replacement of
natural coarse aggregates. Scanning electron microscope (SEM) and X- ray
microcomputed tomography (XRT) is used to quantify the 3-D changes in the pore
structure pf PC mix when RAP aggregates is used. SEM investigation is conducted on
100% RAP validated the involvement of RAP aggregates on PC mixes causes asphalt cohesion failure which will be predominant in reducing the structural and functional
properties of PC mixes. The 3-D pore structure showed the large number of spheroid
shape pores when binary graded PC mix was used. These new findings on the pore
morphology will assist in the optimize use as well as selection of RAP aggregates
when used in PC.
... Reclaimed asphalt pavement (RAP) material is generated when the surface layer of the asphalt pavements are removed for rehabilitation or resurfacing, or to obtain access to buried utilities such as water and natural gas supplies, sewerage pipelines etc. Usually, this RAP material consists of good-quality, well-graded aggregates coated by an asphaltic layer, as reported by Ransinchung et al. [1] and documented by Sing et al. [2] among others. Millions of tons of RAP materials are generated each year globally but suffer from poor practices and standards for the management of such gigantic quantities [3]. ...
... The mathematical expressions for CI and PI are given in Eqs. (2) and (3) below, respectively. CI defines the limits such that there is a 95% probability that the true best-fit line for the population falls within this interval. ...
The use of reclaimed asphalt pavement (RAP) matrials in road construction, maintenance, and rehabilitation projects has a number of economic and environmental benefits. This study evaluates the performance of cement-treated blends prepared by mixing the RAP content with fresh granular (G) material in different percentages and for different curing periods. For this purpose a comprehensive laboratory testing campaign was executed considering the resilient modulus tests, unconfined compressive strength tests, long-term cyclic tri-axial load tests, creep loading tests, and drying shrinkage tests on the blended samples. Analysis of the high-quality test result data demonstrates that applying even a small cement dosage, in the range of 1.5–4.5%, to the blended samples can considerably improve their resilience and strength properties in addition to limiting the accumulative strains occurring under the applied cyclic and sustained creep loading. However, drying shrinkage of the blended sample may be an adverse effect due to the addition of cement content. Additionally, statistical analysis of experimental results shows that resilience and strength properties of the cement-treated blends are significantly dependent on the blend composition and curing period, in addition to cement dosage. A regression model is presented for the estimation of compressive strength of the blended samples, which simultaneously takes into account the blend composition, curing period, and cement dosage.
... For RAP-C-50, RAP-C-75, and RAP-C-100, the modulus of elasticity was reduced by 32%, 36%, and 48%, respectively. These results are similar to those found by other authors (43)(44)(45)(46). ...
The aim of this research is to determine the effect of curing temperatures (20°C, 40°C, and 60°C) and incorporation rates of reclaimed asphalt pavement (RAP) on the mechanical properties and shrinkage of concrete made with reclaimed asphalt pavement (RAP-C). Five mixes were produced for this study: one with natural coarse aggregate and four with four replacement ratios of coarse RAP (25%, 50%, 75%, and 100%). The results show that the use of RAP reduces the workability and adversely affects the mechanical performance of RAP-C. Moreover, this study found that the total shrinkage increases with coarse RAP content. However, the total shrinkage of RAP-C decreases as the curing temperature increases: for concrete made with 100% RAP, a 20% reduction in total shrinkage was observed at 60°C compared to conventional concrete at 180 days. In addition, to predict the total shrinkage of RAP-C, finite element analysis using ANSYS © software based on the maturity approach and the two-phase serial model is used. The numerical results are in close agreement with the experimental data.
... Under these circumstances, reclaimed asphalt pavement (RAP) aggregates which are retrieved when existing asphalt pavement is demolished or milled for reconstruction, rehabilitation, or maintenance activities, can be reused as a component in paver block manufacturing. Considering several factors like scarcity of good quality natural aggregates due to the closure of quarries, generation of enormous amounts of RAP annually worldwide creating pressure on dumping grounds or landfills, and the need for sustainable eco-friendly construction practices, the valorisation of RAP materials as an alternative aggregate source seems quite rational [15,[27][28][29][30][31][32]. However, although the use of RAP in asphalt mixtures for pavement applications is well established, its use in concrete mixes is still restricted to laboratory and few field applications. ...
Recycling of extracted asphalt pavement materials, also known as reclaimed asphalt pavement (RAP), is gaining tremendous interest among researchers globally due to the depletion of good quality natural aggregate reserves and has been successfully employed for various pavement applications. However, an integrated curing condition-based performance assessment is necessary to understand the possible utilisation of these recycled aggregates for precast units like concrete paver blocks (CPBs), which fail to adhere to the standard curing procedures to support mass production. Therefore, the present study attempts to examine the suitability of RAP fractions (coarse, fine, and combined in volumetric proportions of 50% and 100%) for CPB mixes considering the effectiveness of five different curing conditions. The CPB specimens were fabricated implementing a pragmatic design methodology to cater to the need for agglomerated RAP particle refinement and promote maximum utilisation of RAP. The performance assessment mainly focussed on the transport, durability and microstructural properties of hardened CPB specimens subjected to prolonged water curing, air curing, water and air curing, water spray and air curing, and heat curing conditions. Similar to conventional precast concrete mixes, an initial 7 days of water curing or water spraying followed by air curing could be suggested as an alternative curing method to continuous water curing for RAP-based CPB mixes, thereby promoting RAP utilisations in the precast concrete industry from an economic viewpoint. Large voids or pore spaces and micro cracks for the heat cured counterparts make heat curing unsuitable for RAP-based CPB mixes.
... when natural aggregates were replaced by uncleaned and washed 100% coarse RAP. In fact, the addition of 100% surface-treated coarse RAP aggregates caused this value to further rise to 12.85 [108]. When natural fine aggregates were substituted for 25, 50, 75, or 100% of the fine RAP in concrete mixes, Singh et al. [85] observed a lower pH value of 0.3, 1.3, 3.3, and 3.8% as compared to the control mix. ...
... When replacing poor-quality drainage materials, it is necessary to check the materials' drainage and structural capacity. Notable studies reported lower permeability of the pavement materials, less than the required for two lanes pavement (300 m/day) (Jones and Jones, 1989;Grover and Veeraragavan, 2010;Singh et al., 2020;Koohmishi and Azarhoosh, 2021). ...
... These waste materials are in the form of aggregate, which is coated with a layer of asphalt around its periphery. These materials are known as reclaimed asphalt pavement (RAP) aggregates (27)(28)(29)(30)(31)(32)(33)(34). The use of RAP in cement concrete pavements is a novel concept that has attracted much interest because of its underutilization in asphalt pavements (27,35,36). ...
Pervious concrete (PC) is emerging as a novel pavement material for its unique characteristics of reducing storm-water runoff and mitigating urban heat islands. This makes it well suited for low-volume pavement applications. It is also expected that reclaimed asphalt pavement (RAP) aggregates as a replacement for natural aggregates will improve the porosity and permeability of PC pavement mixtures. As a result, this study checks the feasibility of using RAP-based PC mixes in a parking space. The construction process will offer a guide to the field engineer on how to push this technology further when recycled materials are used. The PC parking space, with a capacity of 5 tonnes laden weight, was developed by replacing natural aggregate with 25% RAP aggregate (30% of 10 mm and 70% of 4.75 mm). Field mixtures were found to have higher porosity and lower density when compared with laboratory-prepared mixes. The field infiltration capacity was observed to be in the range of 0.50–1.75 cm/s while maintaining a flexural capacity of 2.36 MPa to 3.17 MPa (342.28 pounds per square inch (psi) to 460 psi). This suggests that using binary-graded RAP aggregates helps create an interconnected pore network, enhancing PC mixtures’ transport capabilities. The present study illustrates the step-by-step construction process of PC pavements for field applications. Based on the findings, it is recommended that 50% could be the maximum feasible limit for the usage of RAP aggregates in PC field mixes.
... Scarcity of aggregate, longer hauling distance for suitable material, and environmental concerns have compelled the decision-maker to incorporate Reclaimed Asphalt Pavement (RAP) in asphalt mixture to replace natural aggregate [1,2]. The RAP content ranging between 10 and 30% is prevalent in road rehabilitation projects. ...
Reclaimed Asphalt Pavement (RAP) is often used with Warm Mix Asphalt (WMA) additive to reduce the production temperature and limit emission at the asphalt plant and worksite. Despite sustainable utilization of RAP, the long-term performance of recycled mix is still quite concerning, and thus research focus on the risk of premature pavement distress. This study is a novel approach to examine the individual and the combined effect of hydrated lime and a warm mix additive (Sasobit) on the long-term performance of the recycled mix. The recycled mixture is comprised of 50% RAP in this study. The study simulated short-term ageing and long-term ageing as per the standard AASTHO R30 ageing protocols on the recycled mix. The properties of recycled mixtures were investigated by Marshall stability, indirect tensile strength, moisture susceptibility, rutting, ravelling resistance, stiffness modulus, and fatigue cracking test. Laboratory findings suggest that the recycled control mix is highly affected by the long-term ageing concerning higher moisture susceptibility, lower fatigue, and cracking resistance properties. However, the individual presence of the additive limits the extent of ageing, where hydrated lime acted as a multifunctional additive, and warm mix additive decreased the moisture and rutting resistance of the mixture in long-term ageing. But it is interesting to note that mix treated with both the additives produce considerable performance enhancement by lowering the ageing and simultaneously depicts higher fatigue and cracking resistance performance of the said mix. Such a result is attributed to the fact that hydrated lime and warm mix additive modify the oxidation kinetics of the mix positively and react with the oxidation products thereby rendering the mix free from deleterious effects.
... Mixtures containing RAP varying from 0-100% and 1, 2, and 3% cement-treated RAP were subjected to various experimental tests and found that increasing RAP quantity decreases the CBR value but within the acceptable limits [13]. The inclusion of coarse RAP doesn't affect the engineering properties of base and sub-base layers in comparison to fine RAP [14]. Many researchers [15,16] have successfully studied the incorporation of RAP in base and sub-base layers for the pavement section. ...
Currently, the scarcity of natural resources has been a significant impact on the construction industry. The demand for fresh aggregate becoming huge due to the increase in the construction of pavement and fulfilling the aggregate requirement is a great concern. In this research, an effort has been shaped to assess the feasibility of the use of Reclaimed Asphalt Pavement (RAP) material for improving the strength properties of the granular sub-base (GSB) layer. RAP aggregate was partially and fully replaced with fresh aggregate in different percentages to test various strength properties. Efforts were being made to improve the strength of the GSB layer by using RAP concerning soaked California Bearing Ratio (CBR) by blending with natural aggregates (NA). To know the best of mix proportions, RAP was partially and fully replaced with virgin aggregate in varying percentages such as 0%, 25%, 35%, 45%, 55%, 65%, and 75%. Modified compaction tests were performed on 100 % RAP and mixtures containing various percentages of RAP to establish the optimum water content for CBR sample preparation. Soaked CBR value was determined at 7 days, 14 days to see the effect of RAP on the GSB mixes. It was observed from the results that the soaked CBR value of RAP improves from 32% over 100% when it is mixed with natural aggregates in varying percentages and made it appropriate for utilizing it as a sub-base of flexible pavement. Depending upon the experimental outcomes, it was deduced that RAP in the sub-base layer is limited to 55% which has exquisite properties as natural aggregates utilized in the road sub-base.
... Based on a literature review from past studies [12,17,34,35], the strength of RAPM in terms of CBR test value increases with the addition of virgin aggregates to the mix. However, in the present laboratory mix design, efforts have been made to use 100% RAPM by adding cement and Stabilroad Stabilizer. ...
Milling of an existing pavement after it's service life engenders massive production of reclaimed asphalt pavement material (RAPM), which may cause disposal issues. The current study highlights the sustainable valorization of RAPM in the cement-treated base (CTB) layer by incorporating chemical stabilizers by the full-depth reclamation (FDR) method. CTB mix was prepared in the laboratory by using 100% RAPM with varying cement and chemical admixture content. In order to identify the effect of different content of cement and chemical stabilizer on the laboratory measured different engineering properties of CTB mix were evaluated. Furthermore, to impart more insights on the laboratory-designed CTB mix under actual traffic conditions, the test track was also laid and being monitored by the durability properties of fields sample and falling weight deflectometer (FWD) analysis. Four cement contents of 3.5, 4.0, 4.5, and 5 percent and five chemical stabilizer contents of 0, 3.0, 3.5, 4.0, and 4.5 percent by weight of cement were added. From obtained data, it can be concluded that mix prepared with 4.5% cement and 4% chemical stabilizer provides the best result in terms of strength parameters and durability properties of studied samples. FWD data advocates that constructed pavement with a designed CTB layer imparts low fatigue behavior as compared with the performance criteria prescribed in Indian Roads Congress (IRC) guidelines. Our study accentuated that 100% recycling of RAPM in FDR technology can be a viable solution as the comprehensive cost analysis showed a 45% cost reduction for the proposed mix by incorporating studied materials.
... Within this scope, the effective recycling of existing but destroyed during operation asphalt pavements allows for a complex approach to construction in accordance with the rules of reclamation and reuse of building materials [4][5][6]. Moreover, in cases of material shortage (aggregate, asphalt, cement), and when supplies "pile-up" as is the case at the end of a working season, using reclaimed asphalt pavement (RAP) is a highly desirable and valuable way to increase the efficiency of roadwork investment [7,8]. ...
The most technologically advanced form of road construction uses a high content of reclaimed asphalt pavement (RAP) as a component of its asphalt mixture (AM). However, there is a real problem with the effective interaction of RAP and MA. The research herein described presents an effective use of RAP originating from the recycling process of old pavements thanks to the application of an original rejuvenator. Two types of AM were designed concerning the base course of pavement as well as the wearing course and the binder course for various traffic categories. The achieved results show that the rejuvenator improved the homogenization of RAP with the asphalt binder and aggregate in each mixture type. On the basis of the research, the possibility of using paving AM with an increased content of RAP in lowered technological temperatures received a favorable assessment. Mixtures of asphalt concrete containing 40% RAP meet both Polish and German requirements for mixtures intended for heavy traffic pavements. Thanks to use of the rejuvenator, it is possible to compact AM layers containing RAP in a final compaction temperature lowered by about 20 °C. The achieved AM lab test results were confirmed on trial road sections. The rejuvenator used in tested AMs improved the homogenization of RAP with both binder and virgin aggregate. Moreover, the study proved that it is possible to use 20%, 40%, and even 100% RAP contents in the mixtures thanks to the use of the rejuvenator based on plant resin and the creation of conditions enabling the effective homogenization of AM components.
... As a result, the consumption of virgin aggregate and asphalt binder is decreased. Many researchers have conducted various studies on the addition of RAP to asphalt mixtures [24][25][26][27][28][29][30][31][32][33]. ...
Asphalt recycling can help reserve natural resources and save money. However, in producing hot mix asphalt (HMA), utilizing reclaimed asphalt pavement (RAP) high heat rate is produced which leads to the stiffening of asphalt binder and producing toxic gases. This in turn will cause massive environmental pollution. As a money-saving technology, Warm Mix Asphalt (WMA) produces asphalt mixture at lower temperatures, and reduces environmental pollution as well as ageing and stiffness of the asphalt binder. This study is aimed at investigating the use of two techniques to decrease environmental pollution, save energy and costs, and improve asphalt mixture performance: WMA technique and RAP materials in asphalt mixtures. The Para-fiber additive was also employed in different values. With respect to the RAP, the use of virgin aggregates was decreased. To compare and evaluate the mechanical performance of asphalt mixtures, tests including resilient modulus, dynamic creep, indirect tensile strength, indirect tensile fatigue, and boiling water tests were conducted. According to the results, using RAP led to an increase in resilient modulus of mixtures and improved the resistance against permanent deformation. Also, by the addition of Para-fiber, the fatigue life of asphalt was improved. Moreover, according to the results of the fatigue test, it was shown that by the addition of RAP, the fatigue life of mixtures was decreased remarkably, yet it was enhanced by using Para-fiber.
... It was considered that, due to its aged conditions, residual bitumen contained in RAP would act as an inert component, with no expected diffusion through the adjacent cement paste. Nevertheless, it was not excluded that it could have some effects on the mechanical properties of the SC-CBMs (Adresi et al. 2019, Singh et al. 2019. ...
This paper presents the results of an experimental investigation which was carried out with the purpose of assessing the performance-related properties of self-compacting cement-bound mixtures to be employed in pavement foundations in road tunnels. The mixtures contained a significant quantity of recycled components and function-specific additives. Characteristics of the mixtures, which were produced in a concrete batch plant, were studied by means of laboratory and field tests. Investigated properties included flowability, compressive strength, resilient modulus and bearing capacity. It was found that mixtures prepared with a cement dosage of up to 100 kg/m 3 possess the required properties of flowability, strength and stiffness. On the contrary, mixtures with higher cement dosages (150 and 200 kg/m 3) fail to meet all the performance-related requirements as a result of their high long-term strength which jeopardises excavatability. Obtained results also highlighted the effects of the different components on the properties of the mixtures and led to the definition of acceptance criteria which can be adopted in actual construction works.
... Some promising results have been found so far with RCA filler (sieved from the bulk material) replacement being shown to improve rutting and fatigue resistance [19], as well as similar cement-based waste fillers [20]. Replacing asphalt mixture aggregates by fraction has been applied successfully in a study with quarry waste materials in asphalt [21] and recycled asphalt pavement (RAP) in PCC [22]. ...
Recycled Concrete Aggregates (RCA) form a significant part of construction and demolition waste and its recycling is crucial for long-term construction sustainability. This study examined the incorporation of various fractions of RCA in Semi-Dense Asphalt (SDA) mixtures. The control SDA aggregates were replaced by RCA in selected fractions of 2/4 mm (coarse) and 0.125/2 mm (sand) at 100% and 50% each, and the filler at 100% of the fraction. The replacement was performed by mass with only one fraction being replaced for any single mixture. The mixtures were evaluated by their volumetrics, indirect tensile strength (ITS), water sensitivity (EN 12697-12), fracture energy and rutting resistance (EN 12697-22), in order to assess the effects of each RCA fraction on the mixture properties. The results showed that RCA coarse aggregates absorb significant amounts of binder and require more energy for compaction, which is not the case for the RCA sand or filler. The ITS results showed increased peak load for the RCA replacement samples but also increased brittleness in terms of resistance to crack initiation and propagation. RCA sand incorporation decreased the fracture energy at a higher rate than the coarse per total amount replaced. The ITSR% was similar to the control for lower amounts of RCA replacement, but significantly lower with higher replacement. The rutting resistance improved with RCA sand and especially coarse aggregate replacement. The study shows some limitations for use of RCA in asphalt mixtures, but also the potential for using them when the replacement rate is limited and replacement by volume is recommended. The RCA filler performance was very similar to the virgin filler, which makes its use in asphalt mixtures especially promising.
... RAP has been extensively used for base and sub-base layers application (Taha et al., 1999(Taha et al., , 2002Arulrajah et al., 2013;Brand and Roesler, 2015b;Avirneni et al., 2016), whereas, a limited studies are available for its usage as wearing course material of concrete pavements (Delwar et al., 1997;Huang et al., 2005Huang et al., , 2006Hossiney et al., 2010;Singh et al., 2017a, b,c;Shi et al., 2017;Mukhopadhyay and Shi, 2017;Shi et al., 2018a,b;Shi et al., 2019a: Singh et al., 2018a. RAP is the reusable material obtained from milling or demolition of an existing asphalt road and this precious material holds potential for re-utilization in asphalt and concrete roads (Taha et al., 2004;Robinson et al., 2004;Brand and Roesler, 2015a;Shi et al., 2017;Singh et al., 2017;Shi et al., 2018a;Singh et al., 2019a). RAP is welcomed as an addition in asphalt pavements owing to reduction in virgin binder content, however, its utilization in concrete pavements is still of meager (Shi et al., 2018b). ...
... Asphalt Pavement Association, asphalt is the most recyclable material, of which more than 99% of asphalt is reusable [3]. Singh et al. [4] used RAP in the different layers of concrete and flexible pavement. They applied coarse and fine graded RAP in granular subbase, wet mix macadam, dry lean concrete, dense bitumen macadam, and plain concrete mix. ...
The incorporation of reclaimed asphalt pavement (RAP) in the construction of new asphalt pavement is limited due to issues with the short-term and long-term performance of pavement. To enhance the aged binder properties, recycling agents (RAs) are added to RAP mixtures. There are different RAs available, and they impact the asphalt binder properties differently, resulting in various aging rates of recycled asphalt. Therefore, in this study, the rheological and chemical characteristics of 100% recycled asphalt binder using different RAs were investigated using Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), and Fourier-Transform Infrared Spectroscopy-Attenuated Total Reflection (FTIR-ATR). The Rolling Thin-Film Oven (RTFO) and Pressure Aging Vessel (PAV) were used to simulate the short-term and long-term aging of asphalt binder, respectively. The long-term aging of the binder was simulated by aging asphalt binder with two PAV cycles. This study aims to identify the proper RA for the recycling of binders according to the aging rate, and the short-and long-term performance of recycled asphalt binder. The results show that the recycled binders with a specific RA that have the minimum initial concentration of sulfoxide and carbonyl could provide better performance in compared to recycled binders with other RAs. This result can be used to predict the long-term performance of recycled asphalt, in addition to identifying the proper RA in the recycling process of asphalt pavement.
Due to increased maintenance and rehabilitation actions, significant volumes of Reclaimed Asphalt Pavement (RAP) are left in stockpiles. Replacing aggregate in Portland Cement Concrete (PCC) with additional RAP could help eliminate surplus RAP stockpiles and reduce PCC's natural aggregate consumption, positively impacting the environment and the economy. This paper is a state-of-the-art review of the literature on using RAP to Roller-compacted Concrete pavement (RCCP). The potential of RAP aggregates has been assessed based on their characteristics and the optimum moisture content (OMC), maximum dry density (MDD), compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, abrasion resistance, shrinkage, porosity, water absorption, and freeze-thaw of RCCP. The literature study illustrated how a low-density, smooth-textured hydrophobic asphalt covering surrounds RAP aggregates. potentially reducing the maximum dry density (MDD) and optimum moisture content (OMC) of RCCP mixtures. This asphalt layer could reduce RAP's ability to bind with cement paste, reducing its strength properties. In addition, the hydrophobic nature of RAP may reduce porosity and water absorption. On the other hand, agglomerates and dust can have the reverse impact. Pavement application might be done with a lower replacement of RAP (less than 50%) without affecting the pavement's strength, porosity, or water absorption. However, Increasing the replacement of RAP aggregate may not be conducive to mechanical performance, but it has the potential to enhance the toughness and energy absorption capacity of pavements.
The key benefits connected with Roller-Compacted Concrete Pavement (RCCP) technology are costs reduction of life-cycle, shrinkage decrease, opening to traffic at an earlier time, and a cooling of the city's core are. This technology received much consideration recently for applications in highway tenders. Several attempts worked on instill sustainable implementation in RCCP using alternate materials. This work presented a thorough review of the literature on alternative materials for RCCP published between 1997 and 2021. Recycled concrete and asphalt pavement aggregates are two examples of alternative materials to traditional quarry rock that have been studied. Critical evaluations of the mechanical properties of RCCP have been used to assess these alternative aggregates' potential. This article explains how the basic properties for the materials impact the RCCP's behavior. The results of a comprehensive study into utilizing the substitute aggregates in manufacturing RCCPs showed the best mix ratios for attaining long-term sustainability. Along with identifying potential future study topics. This research additionally indicates several knowledge gaps that can only be filled by further research and experimentation.
This study explores the utilization of steel slag and fly ash in road construction to address the increasing demand for pavement materials and the scarcity of natural aggregates. For this purpose, steel slag–fly ash composite is stabilized with lime and ground granulated blast furnace slag (GGBS) to assess their utility as a subbase and base material in flexible pavements. Laboratory tests, including compaction and unconfined compressive strength, are conducted on the trial mixes to determine the optimal combinations. Subsequently, durability and resilient modulus tests are performed on the optimum mixes to evaluate their suitability as subbase and base materials. The study identifies the mixes 56% Steel slag + 40% Fly ash + 1% Lime + 3% GGBS and 86% Steel slag + 10% Fly ash + 1% Lime + 3% GGBS as the optimum choices for the subbase layer, while the mixes 76% Steel slag + 20% Fly ash + 1% Lime + 3% GGBS and 70% Steel slag + 20% Fly ash + 1% Lime + 9% GGBS is selected as the optimum mixes for the base layer of flexible pavement and Dry Lean concrete layer for rigid pavement, respectively. After 28 days of curing, the resilient moduli of the optimal subbase and base mixes are 86% and 122% higher than those of conventional granular subbase (GSB) and wet mix macadam (WMM), respectively. Plaxis-3D software demonstrates that the pavement constructed with optimal mixtures in the subbase and base layers has a longer service life than pavement constructed with a conventional granular subbase and wet mix macadam layers. These findings highlight the potential of utilizing bulk quantities of industrial by-products in road construction, offering an environmentally-friendly solution while enhancing pavement performance and longevity.
The cement mortar mixes were developed with the intent of testing the suitability of fine graded reclaimed asphalt pavement aggregates as a replacement for naturally fine materials. The natural fine aggregates were replaced in multiple percent levels of 25%, 50%, 75%, and 100% by weight. The results demonstrate that the mechanical qualities of the mortar mix are deteriorating. To address this, zinc industry waste - jarosite was used as a part replacement for cement in proportions of 5%, 10%, and 15%. Jarosite improved the microstructural, mechanical, and shrinkage properties. For instance, when comparing with the control mix, the mix containing 25% fine reclaimed asphalt pavement aggregates shows a reduction of 5.5% in hardened density and 14% in compressive strength. On the other hand, when 10% jarosite is included in the 25% fine reclaimed asphalt pavement mix, there is an observed increase of 4.85% in hardened density and 7% in compressive strength with respect to the mix containing 25% fine reclaimed asphalt pavement aggregates. As a result, the current study proposes using 10% jarosite when fine reclaimed asphalt pavement aggregates are used to make cement mortar mixes. Furthermore, a cost analysis is performed to determine the difference in construction costs. These findings are expected to inspire rational mix design recommendations for mortar mixes including fine reclaimed asphalt pavement aggregates, as well as bring environmental and economic benefits by lowering carbon footprints.
Reduce, reuse and recycle are treated as the thumb rule for achieving sustainability, and this formula rightly applies to construction materials as they are depleting at an incredible pace. Reclaimed asphalt pavement (RAP) is a sustainable alternative for construction aggregates. Several researchers have identified RAP as inferior material over natural coarse aggregates and proposed incorporating materials like superplasticizers, admixtures, fibers, and pozzolanic materials to compensate for the decrease in mechanical properties. Thus, the present study aims to evaluate the mechanical and durability characteristics of RAP-based roller-compacted concrete with red mud as part addition to cement. The present study considers a constant replacement percentage of 50% by weight of natural aggregates with RAP to evaluate mechanical and durability properties. Upon comparing the fresh properties of RAP-based roller-compacted concrete with red mud over roller-compacted concrete with only natural aggregates, a 3–15% increase in optimum moisture content is observed. Further, the mechanical properties like compressive, flexural, and tensile strengths, which showed a downtrend due to RAP inclusion, have significantly improved by incorporating red mud. However, a 15% red mud by cement weight is observed to be an optimum dosage based on the mechanical properties. Red mud-inclusive mixes outperformed RAP and control mixes in terms of durability characteristics such as water absorption, abrasion loss, and resistance to the aggressive environment. Further, incorporating 15% red mud in RAP-based roller-compacted concrete liberates a lower calcium silica ratio, which ascertains the dense microstructure formation.
Worldwide, flexible pavements are the paramount type of pavements. These national assets can be recycled to serve the next design life without the need to dispose of them in landfill. The old/distressed, flexible pavement material is called, reclaimed asphalt pavement (RAP) material. In view of the sustainable development practice, 100% RAP should be recycled. However, the practical range of RAP incorporation in a drum mix plant ranges from 10% to 50% whereas in a batch mix plant, it is 10% to 35%. In a batch mix plant, incorporation of the hot dried RAP (instead of cold RAP feeding) can increase the RAP incorporation level by 20%. Studies recommended that the rejuvenator should be added over the RAP material instead adding with the base binder. The addition of rejuvenator on the RAP conveyor belt (to the pug mill), provided sufficient time for rejuvenating the aged binder coating over RAP aggregates. Further, a thorough knowledge of the mix design process of recycled hot mix asphalt (RAP-HMA) is essential to produce a durable mix. For high RAP content (>20%), the RAP binder properties are important for the mix design process. However, very limited studies discussed (in detail) the recovery process of the RAP binder. The review article through light on the binder recovery process, method of RAP gradation, specific gravity determination for RAP material, minimum desirable properties of the RAP material etc. This review paper also provides a narrative review of the historical development of RAP-HMA technology, technical aspects related to the procurement of RAP material, mix design and production of the recycled mix. Moreover, the international & national policies/laws for construction and demolition waste are discussed.
Reclaimed Asphalt Pavement (RAP) aggregate with or without cement stabilization is currently used worldwide as a virgin-aggregate replacement material in subbase construction. Paper presents the multiobjective efficiency analysis conducted on the experimental results from the extensive parametric study in order to identify how the level of hydraulic conductivity and the cement addition affect the RAP utilization. The optimum efficiency frontiers have been identified considering the dual optimization based on a set of multi-objective analyses using the Response Surface Method (RSM). The factors of RAP aggregate replacement range (0–100 %) and cement addition variation (0–4%) were considered along with the responses of hydraulic conductivity, compaction, CBR (California Bearing Ratio) and UCS (Unconfined Compressive Strength). Paper reveals that a specific replacement limit of 25–35% provides an efficient RAP aggregate utilization in terms of the considered parameters. It presents a practical design chart to attain an optimum control on the efficient utilization of RAP aggregate in subbase construction considering the levels of targeted hydraulic conductivity and other considered parameters.
Drainage is one of the primary factors considered during the design of pavements. This paper presents the data from large-scale permeameter tests conducted on pavement sections to evaluate the drainage characteristic of geocomposite (GC) embedded subbase layers with and without traffic load. Two types of GCs with 2D core and 3D core were considered to enhance the drainage properties of a subbase layer. The large-scale permeameter test results indicate that the in-plane drainage capacity of the subbase layer improved by about 12 and 22 fold, respectively, for 2D−GC and 3D−GC. The GCs can drain infiltrated water at a rate of more than 300 m/day (in-plane permeability), even if the thickness of the subbase layer is reduced by about 50%. Over the pavement's design life, long-term in-plane permeability is estimated to decrease by 65–70%. It is estimated that the GC embedded subbase layers could drain off 50% of the infiltered water from a two-lane pavement system within 2 h, even after reducing the layer thickness by 100 mm. A set of new drainage coefficients for geocomposite improved subbase layers (m3c) were proposed based on the American Association of State Highway and Transportation Officials drainage quality guidelines.
In the last few decades, much attention has been given to Roller-Compacted Concrete Pavement (RCCP) technology for highway applications due to its numerous advantages over other conventional paving materials; lower life-cycle cost, lesser shrinkage, early opening to traffic, and reduction in the urban heat island are the main benefits associated with RCCP. Efforts have been made in the recent past by researchers to inculcate sustainable practices in RCCP by incorporating alternative materials. The present study is a state-of-the-art review of the studies published between 1997 and 2021 on the use of alternative materials for RCCP. The alternative aggregates that have been considered are recycled concrete aggregates, reclaimed asphalt pavement aggregates, crumb rubber, and electric-arc furnace steel slag aggregates. The potential of these alternative aggregates for RCCP has been critically assessed based on the fresh (optimum moisture content, maximum dry density, vebe time), mechanical (compressive strength, flexural strength, split tensile strength, abrasion resistance, modulus of elasticity), and durability properties (porosity, water absorption, freeze–thaw, and alkali-silica reaction). Consequently, the fundamental parameters of these materials affecting the behavior of RCCP and the ways to address them are summarized. Based on the extensive survey, the optimum proportion of these alternative aggregates for the production of sustainable RCCP have been identified and reported. Various gaps that need to be bridged through scientific as well as field understandings are also highlighted in this paper, along with outlining the possible future research scopes.
Quarry dust is considered as a possible source of natural sand or fine aggregate in concrete construction work. This could reduce the problem of dumping of quarry dust as a byproduct from stone crusher factory. The experimental work investigates the optimum quarry dust percentage which can be adopted as replacement of fine aggregate in concrete mainly for rigid pavement. The quarry dust is added at different percentages of 0%, 20%, 40%, 60%, 80%, and 100% replacement of fine aggregate for M35 grade concrete thereby to find out the optimum content of quarry dust that can give better strength in concrete. Mix design has been developed for M35 grade of concrete as per IRC 044 – 2017(Mix Design for Concrete Pavement) and mix design ratio is found as 1: 1.6: 2.62 by using Sulfonated naphthalene formaldehyde (SNF) as an admixture at 1%, and 2%. The required water cement ratio was obtained as 0.39 according to table no.9 of IRC 044 for the target strength of 42.5 N/mm ² . Optimum strength and workability test values of concrete made up for various proportions of quarry dust along with SNF are compared with conventional concrete of natural fine aggregate after 7 days and 28 days curing. It is found that the strength increased with the increase in curing time and the maximum strength at 28 days curing and 60% quarry dust replacement with 2% addition of SNF. The maximum strength of quarry replaced concrete is obtained as 40.3MPa, 5.6MPa, and 5.1MPa for compressive, flexural, and split tensile respectively.
Reclaimed asphalt pavement (RAP) is one of the innovative and effective technologies in many places in the world. The utilization of RAP is rapidly increasing popularity and becoming an emerging technique in India. As per IRC-120:2015, removing or reprocessing pavement materials containing aggregates that are bitumen coated is termed as RAP. These materials are gained through a process in which the existing surface pavement is reclaimed and reused after processing for reconstruction, resurfacing, or repaving. Well graded and high-quality aggregate are achieved from this process. Proper utilization of RAP with specified properties and specified percentages, not only serve as an alternative useful pavement material but also helps in reducing the usage of natural construction material, that will directly reduce the overall cost of projects. By conducting tests as per MoRTH specifications (5th Revision), the various characteristics of RAP material and fresh aggregates are observed. The main objective of the study is to carry out the performance tests: Modified Proctor test on fresh material as well as on material mixed with reclaimed asphalt pavement i.e. 10%, 20%, and 30% of total mix and to achieve optimum moisture content and maximum dry density by using Modified Proctor Test. Attempts are carried out to design a new pavement using Indian Road Congress (I.R.C-37:2018) guidelines and utilization of RAP material. Economic benefits are calculated in terms of fresh and RAP (10%, 20%, and 30%) mix material pavement.
This paper investigates mechanical properties of roller compacted concrete (RCC) involving reclaimed asphalt
pavement (RAP). In this way, a set of 276 cylindrical RCC specimens were prepared with different RAP sizes (i.e., fine, coarse & total) at various ratios (i.e., 10%, 20%, and 40%). Results reveal that incorporation of RAP decreases unconfined compressive strength (UCS), modulus of elasticity (E), and indirect tensile (IDT) strength of RCC. For each RAP size, a regression model was used to maximize RAP content while satisfying the UCS lower limit (27.6 Mpa) mentioned by ACI as a minimum requirement for RCC used in pavement construction. Moreover, UCS of RAP incorporated mixes, dissimilar to that of control
mixes, was found to be sensitive and insensitive to the testing temperature and curing time after 7 days, respectively. The results also demonstrate that the higher amounts of RAP, the more flexibility in RCC is. This issue was also proved by the results of modulus of elasticity test. In addition, the toughness index (TI) shows that increase in RAP content leads to up to 43% increase
in energy absorbance capacity of RCC.
Recycling of flexible pavement leads to the accumulation of an enormous quantity of Reclaimed Asphalt Pavement (RAP) aggregates which are generally dumped legally/illegally in the nearby vicinities causing several challenges to the agencies. Utilization of these aggregates in cement concrete pavements seem to be a novelistic approach and could facilitate with many socio-economic-environmental benefits. However, its inclusions may negatively affect structural and functional performance as well. Therefore, this paper presents an extensive and critical review of the suitability of RAP for the production of concrete mixes along with identifying the various gaps that need to be bridged to induce sustainability in pavements. The schematic flow of this paper is as follows: firstly, the RAP aggregates were characterized, followed by the fresh state RAP-concrete properties, and lastly, the mechanical and durability properties were investigated. The literature review depicted that the RAP aggregates are inferior to natural aggregates but it may not be a big concern from the point of fresh state properties. The presence of asphalt film and agglomerated particles in RAP were noted to be the primary factors responsible for the reduction in the overall strength properties; however, coarse and fine RAP (individually) up to 50% could be utilized since the minimum strength benchmarks could be met. In terms of durability, coarse RAP up to 50% may provide adequate chloride-ion penetration resistance and freeze–thaw durability. Benefits such as enhanced toughness and workability were positively identified by the incorporation of RAP, whereas, porous microstructure could be expected, which may provide passage to aggressive ions from nearby environments resulting in significant deterioration of the concrete. Including supplementary cementitious admixtures could not improve the mechanical performance due to the asphalt cohesion failure associated with these hybrid mixes, but durability performance could be enhanced slightly. On the other hand, surface treatment methods could improve the bonding potential between RAP and mortar paste. This review is expected to address several key issues on the utilization of RAP in cement concrete pavements and encourages academicians and highway agencies to form a framework for effective utilization of RAP for sustainable pavement systems.
The utility of reclaimed asphalt pavement (RAP) in rigid pavements has been previously utilized for pavement quality course (PQC) with very few investigations available on assessing the effect of RAP gradation in dry lean concrete (DLC) layer. RAP poses various environmental concerns including disposal problem and hence it becomes imperative to incorporate this waste material for the construction of sub base layers such as DLC. This paper studied the influence of RAP on the density and strength properties of DLC. In this study, RAP was proportioned on the basis of black curve gradation (BCG) and true curve gradation (TCG). Mix parameters such as density and compressive strength were studied to quantify the effect of RAP using the fractionation method. Fractionated Reclaimed Asphalt Pavement (FRAP) was found to be significant in influencing the behavior of DLC. 60FRAP (60% fractionated RAP) was the first fraction to achieve the benchmark of 7 day compressive strength of DLC, followed by the lower contents of FRAP. Statistical inferences indicated that, along with moisture content, RAP significantly influences the structural behavior of DLC composites. However, the effect of RAP was insignificant with respect to density. Additionally, a simple approach of economic analysis was adopted, which indicated that FRAP is economically feasible for the construction of DLC layer in rigid pavements.
Utilisation of reclaimed asphalt pavement (RAP) aggregates in concrete mixes generally results in strength reductions owing to asphalt-cohesion failure. Therefore, the present investigation is an effort to improve the RAP inclusive roller compacted concrete pavement (RCCP) properties by incorporating supplementary cementitious mineral admixtures (SCMs). Incorporation of 50% RAP aggregates lowered the strength and durability properties of the RCCP mix considerably. Inclusions of SCMs showed an almost negligible effect on the fresh properties; but had a prominent effect on the mechanical properties of 50RAP mix, thus, indicating their unsuitability for RAP–RCCP mixes if added in a sight to enhance its strength. However, almost all the mixes achieved the minimum stipulated flexural strength benchmark, and hence, could be recommended for RCCP mixes. Utilisation of silica-fume and bagasse-ash were further noted to improve the abrasion resistance of 50RAP mix. Likewise, the considered SCMs were also able to reduce the porosity and absorption related properties considerably and enhanced its durability in acidic environments of sulphate and chloride-rich ions. Based on the study, it is suggested to avoid the use of SCMs, if strength enhancement is the requisition, however, its utilisation is firmly suggested in order to enhance the durability performance of RAP-RCCP mixes.
This paper is an attempt to enhance the long-term performance of Reclaimed Asphalt Pavement (RAP) inclusive dense bituminous macadam (DBM) mixes, in post ageing condition, via inclusions of a Warm Mix Additive. Two sources of Reclaimed Asphalt Pavement (RAP) with two inclusion proportions (35% and 70%) were considered. The effect of inclusions of both the technologies (RAP & WMA) on various properties of DBM mixes such as Marshall Stability, retained Marshall Stability, indirect tensile strength (wet & dry), rutting resistance and Cantabro abrasion loss were studied. Inclusions of WMA was found to significantly improve the aforementioned properties of the DBM mixes regardless of the type of aggregate used. Moreover, the RAP-WMA mixes were found to retain much of its properties even after long-term ageing as compared to RAP-HMA mixes. RAP fraction up to 35% may be used for DBM mixes without much compromising the mechanical and durability properties of the same (as found in the present study). Incorporation of WMA in these mixes would further improve the properties and would ensure the longevity even in the worst conditions of moisture.
The influence of reclaimed asphalt pavement (RAP) on the mechanical properties of cement-treated materials (CTMs) has not been completely understood, while its usage as a partial supplement of virgin aggregates in road layers has been investigated by many researchers for its eco-friendly aspects. In addition, CTMs containing high contents of RAP have not yet been widely applied. Therefore, this paper aimed to experimentally investigate cement-treated base mixtures containing high percentages of RAP in terms of mechanical properties in different environmental conditions to find a proper opportunity to increase the recycling rate of this valuable material. In this regard, mixture design formulation was determined based on modified effort compaction test results as well as unconfined compressive strength and indirect tensile strength tests of seven-days cured samples. Also, critical condition of hot-summer and wet winter circumstances were taken in to account as prepared cylinder samples were dry-cured under 50 °C and wet-cured under 25 °C, respectively. Results indicate that incorporation of RAP materials increases optimum moisture content (OMC), and therefore, reduces maximum dry density (MDD). Additionally it is found that, temperature of 50 °C in RAP incorporated mixes and moisture in control mixes are critical conditions for determining strengths and finally, structural design of pavement.
Reclaimed Asphalt Pavement (RAP) is the result of removing old asphalt pavement material. RAP consists of high quality well-graded aggregate coated with asphalt cement. The removal of asphalt concrete is done for reconstruction purposes, resurfacing, or to obtain access to buried utilities. The disposal of RAP represents a large loss of valuable source of high quality aggregate. This research investigates the properties of concrete utilizing recycled reclaimed asphalt pavement (RAP). Two control mixes with normal aggregate were designed with water cement ratios of 0.45 and 0.5. The control mixes resulted in compressive strengths of 50 and 33 MPa after 28 days of curing. The coarse fraction of RAP was used to replace the coarse aggregate with 25, 50, 75, and 100% for both mixtures. In addition to the control mix (0%), the mixes containing RAP were evaluated for slump, compressive strength, flexural strength, and modulus of elasticity. Durability was evaluated using surface absorption test.
Full-depth and two-lift concrete slabs were cast with fractionated reclaimed asphalt pavement and recycled concrete aggregate as partial and full replacements of the coarse aggregate in a ternary blend concrete containing cement, slag, and fly ash. These large-scale slabs were monotonically loaded at the edge to quantify the effect of recycled aggregates on the slab's flexural capacity. Although the introduction of these recycled aggregates into the concrete reduced the compressive, split tensile, and flexural strengths as well as the elastic modulus of the concrete relative to virgin aggregate concrete, fracture testing demonstrated that recycled concrete aggregate can have fracture properties statistically similar to those of virgin aggregate concrete. Testing of the flexural capacity of the slabs revealed that concrete with recycled aggregates had peak loads at failure similar to or greater than those of virgin aggregate concrete despite a significant difference in beam flexural strength. The calculated tensile stress in the slab at flexural failure was underpredicted by the beam flexural strength by a factor of 1.5 for virgin aggregate concrete and 1.9 to 2.7 for concrete with recycled aggregates; these findings demonstrate that the beam flexural strength results are not always reliable predictors of slab capacity, especially with recycled aggregates. Because of lower beam flexural strengths with recycled aggregates, pavement engineers should compare the fracture properties of concrete containing recycled aggregate with those of typical virgin aggregate concrete before deciding whether to increase the required concrete slab thickness.
This paper presents research evaluating the effectiveness of rejuvenators
for production of very high (40% to 100%) reclaimed asphalt pavement
(RAP) content mixtures. Nine differently originated softening agents were
tested; these included plant oils, waste-derived oils, engineered products,
and traditional and nontraditional refinery base oils. Two different
dosages of the agents were added to binder extracted from RAP to
evaluate their softening potential through testing of kinematic viscosity
and penetration at two different temperatures. At 258C the softening
efficiency varied by a factor of 12 between the most and least effective
rejuvenators. Consistency results at different temperatures were used
to express temperature susceptibility by means of penetration index
(PI), penetration–viscosity number, and bitumen test data chart of the
softened binders. The PI results varied measurably depending on the
rejuvenator and supported the low-temperature mixture test results,
showing that PI may be a good and simple measure of rejuvenation
effectiveness. Low-temperature mixture embrittlement was evaluated
at 2108C through determination of the indirect tensile strength and
creep compliance for rejuvenated 100% RAP mixture samples. It can
be concluded that four of the nine tested rejuvenators reduced extracted
binder consistency to the necessary level and reduced susceptibility of
RAP mixtures to low-temperature embrittlement. Of the four, two engineered
products tested had notably different performance but neither
was superior to similar generic oils.
This study evaluated the rutting resistance, moisture susceptibility, and fatigue resistance of warm-mix asphalt (WMA) mixtures containing high percentages of reclaimed asphalt pavement (RAP) through laboratory performance tests. The WMA mixtures were plant produced with a foaming technology commonly used in the United States. RAP content ranged from 0% up to 50%. Laboratory performance tests included the asphalt pavement analyzer rutting test, the Hamburg wheel-tracking test, the tensile strength ratio test, the Superpave® indirect tension test,
and the beam fatigue test. For comparison purposes, hot-mix asphalt
mixtures containing 0% and 30% RAP were also evaluated and compared
with WMA. The laboratory test results indicated that WMA
mixtures with high percentages of RAP exhibited higher resistance
to rutting, better resistance to moisture damage, and better fatigue
performance.
Tests were conducted to determine the saturated hydraulic conductivity of three recycled asphalt pavement (RAP) materials being used as base course aggregate for pavement construction. Comparative tests were also conducted on a compacted crushed rock aggregate (Lodi gravel) that is used for base course in Wisconsin. All four are granular materials. The RAPs have saturated hydraulic conductivities ranging from 2.4 x 10 -5 to 9.0 x 10 -5 m/s when compacted with standard Proctor effort and from 4.5 x 10 -8 to 1.7 x 10 -6 m/s when compacted with modified Proctor effort. The Lodi gravel is less permeable, having saturated hydraulic conductivities of 5.8 x 10 -7 m/s (standard Proctor effort) and 2.4 x 10 -9 m/s (modified Proctor effort). Three conventional methods of predicting the saturated hydraulic conductivity of coarse-grained soils were evaluated in terms of their ability to predict the saturated hydraulic conductivity of RAP: Hazen's equation, Kenney's equation, and the Kozeny-Carmen equation. Each of these equations overpredict the hydraulic conductivity of RAP. Two empirical equations to predict the hydraulic conductivity of RAP were developed from the saturated hydraulic conductivity data. The empirical equations were found to work well for RAP as well as the Lodi gravel. However, the empirical equations are based on a small data set. Updating of the equations is encouraged as more data become available.
Pavement rehabilitation and reconstruction generates large quantities of reclaimed asphalt pavement (RAP) aggregate, and recycling into new asphalt paving mixtures is the predominant application. RAP acceptance in road bases and subbases has been limited, because of the lack of laboratory and field performance data. In the Sultanate of Oman, recycling of pavement materials is not practiced. A previous study conducted at Sultan Qaboos Univ. indicated that RAP-virgin aggregate mixtures could be utilized in the subbase layer rather than in the base course. This paper presents the results of a laboratory evaluation of cement stabilized RAP and RAP-virgin aggregate blends as base materials. Compaction and unconfined compressive strength tests were conducted on the following RAP/virgin aggregate mixtures: 100/0, 90/10, 80/20, 70/30, and 0/100%. Samples were prepared using 0, 3, 5, and 7% Type I portland cement and were cured for 3, 7, and 28 days in plastic bags at room temperature. A pavement design analysis of using various cement stabilized RAP-virgin aggregate mixtures as base materials was also undertaken. Results indicate that the optimum moisture content, maximum dry density, and strength of RAP will generally increase with the addition of virgin aggregate and cement. Longer curing periods will yield higher strength results. The ability of RAP aggregate to function as a structural component of the pavement is more pronounced when it is stabilized with cement rather than when blending with only virgin aggregate. A 100% RAP aggregate should not be recommended for use as a base material unless stabilized with cement. Cement stabilized RAP-virgin aggregate mixtures seem to be a viable alternative to dense-graded aggregate used in road base construction.
Recycled asphalt pavement (RAP) is the removed and/or reprocessed pavement material containing asphalt and aggregate. The use of RAP in asphalt pavement has become common practice in the construction of new, and reconstruction of old, hot-mix asphalt (HMA) pavements. However, little research has been done to examine the potential of incorporating RAP into Portland cement concrete (PCC) to replace virgin aggregate. In a previous study by the first two of the current authors, laboratory-prepared RAP was used to investigate the potential use of RAP in PCC. The present study focused on the evaluation of mechanical properties of PCC made with real RAP materials through laboratory experiments. Two types of RAP materials (coarse and fine RAP) were used to replace an equal amount of virgin coarse and/or fine aggregate. Silica fume and high-range water-reducing agent (HRWRA) were also added into concrete mixtures to minimise the strength loss resulting from the incorporation of RAP. A total of 17 concrete batches were cast and evaluated for compressive and split tensile strengths, static compressive modulus of elasticity and toughness index. Test results indicated that there was a systematic reduction in the
strengths and elastic modulus as well as an increase in the toughness index with the increase in RAP content. While the addition of HRWRA into the matrix improved the mechanical properties of concretes containing RAP, addition of silica fume did not.
Recycled asphalt pavement (RAP) is the removed and/or reprocessed pavement material containing asphalt and aggregate. The use of RAP in asphalt pavement has become a common practice in the construction of new, and reconstruction of old, hot mix asphalt (HMA) pavements. But little research has been done to examine the potential of incorporating RAP into concrete. Since RAP contains asphalt, it is very likely that the toughness of concrete made with RAP could be improved. In the present study, the mechanical properties of RAP-incorporated Portland cement concrete were investigated through laboratory experiments. Two types of RAP (coarse and fine RAP) materials were considered. The results from this study indicated that RAP could be incorporated into Portland cement concrete without any modification to the conventional equipment or procedures. Without any treatment, there was a systematic reduction in the compressive and split tensile strengths with the incorporation RAP in concrete. Notably, the energy absorbing toughness for the RAP incorporated concrete has been significantly improved.
The present investigation promotes the usage of RAP for developing countries like India where hot mix asphalt is still the most popular and utilized technology. Dense Bituminous Macadam (DBM) mixes were prepared with different proportions (50% & 100%) of coarse RAP (C), fine RAP (F) and total RAP (T) obtained from two different sources separately. This approach was adopted owing to the fact that uncontrolled milling is still the most practically doable method for reclaiming RAP. The optimum proportion of RAP for DBM mixes was decided based upon several strength and durability properties. It was found that C mixes demand higher quantity of virgin asphalt followed by F and T mixes for achieving the desirable volumetric properties. T mixes were found to have the highest Marshall Stability value whereas rest of the mixes could attain comparable stability value. Similarly, the rutting performance of all the mixes was significantly higher than the control mix; however, F mixes showed comparable performance to T mixes. On the other hand, both the individual fractions of RAP had comparable moisture resistance (tensile strength ratio) to the control mix, whereas, total fraction mixes could not meet the minimum specified limits. Even the abrasion resistance of C and F mixes in standard condition was higher than the control mix. The results indicated that natural coarse and fine aggregates may be replaced completely by coarse RAP and fine RAP, respectively, for preparation of DBM mixes without much affecting the performance-related properties. Also, this combination would provide a cost saving of about 40%
Free 50 online copies are here: https://www.tandfonline.com/eprint/MfKtjGWWFuDuwBz3VEh6/full The restricted use of reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) motivates the use of RAP in portland cement concrete (PCC) as an aggregate replacement. The addition of RAP causes significant changes in PCC’s properties, but little research has been done to investigate the impact of these changes on pavement performances. In this study, punchout performances of continuously reinforced concrete pavement (CRCP) made with PCC containing RAP (RAP-PCC) slabs have been extensively assessed using existing models in the Pavement ME. According to the findings of this study, the major drawback for using RAP in CRCP is the RAP-PCC’s reduced modulus of rupture (MOR); the reduced MOR causes higher stress to strength ratio in the slab, which can lead to higher chances of fatigue. However, the RAP-PCC slab is anticipated to have tighter transverse cracks due to the reduction in modulus of elasticity. A decrease in crack width could potentially yield a higher transverse crack load transfer efficiency (LTE). The Pavement ME simulations indicate that the CRCP made with RAP-PCC, which has tighter cracks, is able to maintain a higher LTE for a much longer time and ultimately leads to a longer pavement service life compared to the plain CRCP. The limitations of this study along with the related future work are acknowledged at the end of this paper.
This research examines how the addition of recycled asphalt pavement (RAP) changes the volumetric and mechanistic properties of asphalt mixtures. A Superpave® 19-mm mixture containing 0% RAP was the control for evaluating properties of mixes containing 15%, 25%, and 40% RAP. Two types of RAP were evaluated: a processed RAP and an unprocessed RAP (grindings). Testing included dynamic modulus in tension and compression, creep compliance in compression, and creep flow in compression. Dynamic modulus and creep compliance master curves were constructed with the use of the time–temperature superposition principle to describe the behavior of each mix over a range of temperatures. The voids in mineral aggregate (VMA) and voids filled with asphalt (VFA) of the RAP mixtures increased at the 25% and 40% levels, and there was also an influence of preheating time on the volumetric properties. The dynamic modulus of the processed RAP mixtures increased from the control to 15% RAP level, but the 25% and 40% RAP mixtures had dynamic modulus curves similar to that of the control mixture in both tension and compression. The creep compliance curves showed similar trends. A combination of gradation, asphalt content, and volumetric properties is likely the cause of these trends.
In the present study, the suitability of coarse (C) and fine (F) RAP aggregates extracted from two flexible pavements (OLD (O) & NEW (N)) having different service (20 yrs. & 2½ yrs.) and stockpiling life (8 months & 0 months) for productions of Dry Lean Concrete (DLC) and bituminous mixtures is assessed. For the same, a total of 15 DLC mixes were cast, consisting of 9 mixes containing different proportions (25–100%) of CO and CN aggregates and 6 mixes containing FO (25–100%) and FN aggregates (25% and 50%). The effect of both fractions of RAP on optimum moisture content (OMC), maximum dry density (MDD), compressive strength, water absorption and permeable voids were studied. Volumetric properties of compacted bituminous mixes containing aggregates milled from new pavement were also investigated. It was found that aggregates obtained from old pavement have the potential to replace 75% coarse and 50% fine natural aggregates whereas 25% CN and zero FN aggregates may be utilized for DLC mixes. Contrary, aggregates obtained from new pavement were found to be suitable for construction of base and wearing course of flexible pavements whereas aggregates from older pavement could not be even molded while preparing test sample due to loss of binding properties of asphalt mixtures by virtue of oxidation process.
Poor affinity of asphalt toward mortar paste has been testified as the primary reason for reducing the reclaimed asphalt pavement (RAP)–inclusive concrete properties, although the effect of dust present in RAP aggregates due to extraction of RAP using demolition techniques has not been investigated so far. The present paper discusses the effect of different extraction methods on the mechanical properties of fine RAP aggregates. Also, the effect of incorporation of fine RAP aggregates on fresh, mechanical, and durability properties of concrete
has been investigated. It was found that as the substitution level of fine natural aggregates (NA) by fine RAP (0, 25, 50, 75, and 100%) increases, the properties of concrete tend to decrease gradually. From the present laboratory investigation, it is learnt that 50% fine RAP (extraction made using demolition technique) can be used for construction of major highways, whereas 100% fine RAP may be suggested for less important roads and in lower layers of pavement.
The present study investigates the potential of waste originating from road sector (RAP) and agricultural industry (Sugarcane Bagasse Ash) for production of concrete mixes. 5 mixes were prepared by partial replacing natural aggregates by coarse RAP (CRAP) and fine RAP (FRAP) in the proportions of 50% and 100%. 3 subsequent mixes were prepared by incorporating 100% RAP aggregates blended with 10% and 15% Bagasse Ash (BGA) as part replacement of cement. It was noted that incorporations of FRAP aggregates decreased the fresh, mechanical and durability properties of concrete significantly compared to CRAP aggregates. Incorporation of 10% BGA was found to enhance the mechanical and durability properties of 100% RAP concrete significantly. Economic analysis of the considered mixes showed that incorporations of RAP aggregates blended with BGA can reduce the total cost of 1 m³ concrete by more than 40% as compared to conventional concrete. From the present study, it is recommended to replace 10% of cement by BGA in RAP concrete as this would not only strengthen the pavement but provides with environmental and economic benefits.
This paper investigated the effects of concurrent recycling of fine reclaimed asphalt pavement (RAP) and
coarse steel slag aggregate (SSA) on fracture resistance of asphalt mixes. To this end, a set of 576 Semi-
circular bending (SCB) specimens with different ratios of these two marginal materials with and without
warm mix asphalt (WMA) additive were prepared in two aging levels and underwent up to five freeze
and thaw (FT) cycles. Following, specimens were tested at 25 �C in three-point bending configuration
and their critical strain energy release rate (Jc) and flexibility index (FI) were determined and statistically
compared to each other. Results disclosed that FT cycles, long-term (LT) aging and the inclusion of RAP
decrease the fracture resistance, while the inclusion of SSA increases it. Moreover, incorporation of
RAP improves the moisture susceptibility of asphalt mixes, while incorporation of SSA increases this sus-
ceptibility. Overall, concurrent incorporation of SSA and RAP was found to be beneficial in improving the
fracture resistance and moisture susceptibility of conventional asphalt mixes.
The presence of dust, asphalt film and agglomerated particles is considered to be the primary reason for reducing the properties of Reclaimed Asphalt Pavement (RAP)-inclusive concrete. A surface treatment method Abrasion and Attrition (AB&AT) was employed for removing these contaminants. Gaps were identified from the available literatures and efforts have been made to bridge them in order to increase the usage of RAP aggregates in concrete pavements. Six mixes were prepared by partly replacing the Natural Aggregates (NA) with RAP aggregates in different proportions. It was learnt that processing Dirty RAP (DRAP) aggregates by the AB&AT method could remove contaminants considerably as a result of which stronger bonding is exhibited at the interface of the aggregate and hydrated mortar matrix. Incorporation of beneficiated RAP aggregates in concrete improved the workability considerably but it was found to have reduced hardened concrete properties. However, the results were found to lie within the permissible limits for producing concrete mix having 40 MPa compressive strength.
This study deals with improvement in the properties of ABTRAP (Beneficiated RAP aggregates by Abrasion & Attrition technique) inclusive concrete by incorporating mineral admixtures such as Silica Fume (SF), Fly ash (FA) and Sugarcane Bagasse Ash (SCBA). 6 mixes were prepared by partially replacing Ordinary Portland Cement (OPC) by SF (5% &10%), FA (10% & 20%) and SCBA (5% & 10%). Maximum improvement in compressive, flexural and split tensile strength of ABTRAPC mix was found when 10% OPC was part replaced by SF followed by 20% replacement by FA and 5% replacement by SCBA. Even SF10 mix showed comparable strength to that of natural aggregate concrete (NAC) mix. Reductions in permeable voids, water absorption, initial rate and coefficient of water absorption and improved abrasion resistance was observed for all the considered mixes. A power regression equation (flexural strength = 0.368 x (compressive strength)0.72) of high co-relation (R2=0.93) was established to predict flexural strength from compressive strength results of ABTRAPC mixes. Based on the finding of the present part of investigation, it is recommended to replace 10% OPC by SF, FA (20% in sulphate free environment) and 5% by SCBA in ABTRAP inclusive concrete mixes.
One potential solution to reduce the amounts of extra reclaimed asphalt pavement (RAP) stockpiles is to use RAP as an aggregate replacement in portland cement concrete (PCC). This study investigated whether partial replacement of virgin coarse aggregate by coarse RAP is a practically viable option to formulate PCC paving mixtures. The results showed that replacing virgin coarse aggregate by coarse RAP with sufficient intermediate size particles offers the benefits of achieving dense combined aggregate gradation. Measuring relevant mechanical properties followed by developing a procedure to determine optimum RAP replacement levels and guidelines and recommendations for designing PCC containing RAP were conducted and presented in this paper.
Foamed warm-mix technology can decrease the construction temperatures of asphalt mixtures, and recycling reclaimed asphalt pavement (RAP) can reduce waste production and resource consumption. Therefore, combining foamed warm-mix asphalt with RAP is an energy saving and resource recycling technology for pavement construction. However, few studies have focused on the interaction of new asphalt and RAP binder to determine the optimum amount of RAP binder in foamed warm-mix recycled asphalt by the rheological characteristics. In this study, foamed warm-mix recycled asphalts with different amounts of RAP binder were prepared in the laboratory. The influences of the amount of RAP binder on the rheological characteristics of foamed warm-mix recycled asphalt were investigated. The high-temperature and low-temperature performance, temperature susceptibility, antifatigue performance, recovery ratio (R%), and nonrecoverable creep compliance (Jnr) were evaluated by temperature sweep tests, low-temperature bending tests, and multiple stress creep recovery (MSCR) tests. The results show that foamed warm-mix recycled asphalt exhibited better high-temperature performance, temperature susceptibility, and creep properties but inferior low-temperature performance and fatigue resistance. Furthermore, the optimum amount of RAP binder in foamed warm-mix recycled asphalt is higher than that in hot-mix asphalt.
The presence of asphalt film around Reclaimed Asphalt Pavement (RAP) aggregates has been reported as the main factor lowering the properties of RAP inclusive concrete. A novel Abrasion and Attrition (AB&AT) technique to improve the quality of RAP by removing the contaminant layers of dust and punching the asphalt film adhering to RAP aggregates is introduced in this paper. The effect of incorporating Dirty RAP (DRAP), Washed RAP (WRAP) and AB&AT treated RAP, on the fresh, mechanical and durability properties of concrete are also investigated and compared with each other. The mechanical properties of RAP aggregates were found to be increased significantly on processing with AB&AT method. Beneficiation of RAP by AB&AT method increased the compressive strength of concrete by 9.74% &12.71%, split tensile by 2.66% &12.21% and flexural strength by 6.05% & 8.55% as compared to WRAP and DRAP inclusive concrete. Incorporation of RAP into concrete mix improved workability & cohesiveness. Durability properties of concrete such as water absorption, initial rate of water absorption, total permeable voids and coefficient of water absorption were observed to be reduced for RAP inclusive concrete.
Incorporation of electric arc furnace (EAF) steel slag aggregates in asphalt mixes boosts their perfor-
mance, but the high bitumen consumption is the primary obstacle that hinder their widespread applica-
tion. To remove this barrier this research investigates the effects of concurrent recycling of reclaimed
asphalt pavement (RAP) and steel slag aggregates into the warm mix asphalt (WMA) mixes. To this
end, six types of WMA asphalt mixes with two coarse steel slag contents (0% and 40%) and three fine
RAP contents (0%, 20% and 40%) were prepared and their moisture resistance, resilient modulus, dynamic
creep and fatigue behavior were evaluated and statistically were compared to each other. Results showed
that contrary to the steel slag, RAP clearly improves resistance to moisture damage of mixes. The addition
of RAP to the WMA also increases the resilient modulus at all the temperatures; however, addition of
steel slag only at intermediate and high temperatures leads to improvement in the resilient modulus.
Nonetheless, sensitivity of resilient modulus to the temperature decreases with incorporation of both
marginal materials. Moreover, it is found that adding RAP and/or steel slag significantly improves the
number of cycles that the asphalt mix can tolerate in both dynamic creep and indirect tensile fatigue tests
(ITFT). In addition, it is demonstrated that the fatigue behavior of RAP- and/or slag-incorporated mixes
has a lower sensitivity to stress level, with the exception of mixes containing 40% coarse steel slag along
with 40% fine RAP materials. Overall, simultaneous incorporation of steel slag and RAP materials into the
WMA is proven to be an economic and environment-friendly option with a comparable or even better
performance with respect to conventional WMA.
The biggest contributor to the energy consumption (up to 90% of the total) in the Asphalt plants is the fuel used for heating and drying the virgin aggregates in processing of Reclaimed Asphalt Planings (RAP). Proposed review evaluates the currently used technologies to process RAP into Asphalt mixtures. Theoretical comparison is conducted for all the technologies to obtain the effects they have on energy consumption, carbon emissions and costs. The proposed research will evaluate different technologies for RAP mixing and potential benefits technology can bring in terms of cost and greenhouse gas mitigation. Comparative analysis shows parallel drum dryer are most efficient and emit less greenhouse gas with comparison to other discussed technologies.
Reclaimed asphalt pavement (RAP), when used as a coarse aggregate, has been shown to reduce bulk concrete strength and modulus. Part I of this study quantifies and compares the interfacial transition zone (ITZ) for mortar with RAP aggregates relative to dolomite aggregates through image analysis of backscattered electron micrographs. The ITZ with RAP aggregates was larger and more porous with less calcium silicate hydrate (C-S-H) and calcium hydroxide (CH) at the asphalt interface compared with dolomite aggregates. The CH morphology was not significantly affected, although the presence of the asphalt layer may be affecting the CH growth. The addition of silica fume reduced the porosity and size of CH particles in the ITZ with RAP, but not sufficiently to be similar to the ITZ of the dolomite mortar. The microstructural changes caused by RAP aggregates, primarily the larger, more porous ITZ, provide strong evidence for the observed reduction in concrete strength and modulus.
Reclaimed asphalt pavement (RAP), when used as an aggregate in concrete, will reduce bulk concrete strength and modulus. While Part I of this study investigated the properties of the interfacial transition zone (ITZ), Part II focuses on the nature of the cement-asphalt bond. Several chemical oxidative treatments of the asphalt were found to improve the interfacial cement-asphalt bond energy without affecting the ITZ porosity and size. Based on surface free energy measurements, the failure mode was estimated to occur preferentially as asphalt cohesion rather than cement-asphalt adhesion or ITZ cohesion. Based on the findings from Parts I and II, RAP aggregates reduce concrete strength and modulus because of: (1) the higher porosity in the ITZ, which produces a lower bulk modulus and allows for easier crack initiation, and (2) the preferential asphalt cohesion failure, which occurs rather than adhesive failure of the cement-asphalt interface or cohesive failure of the ITZ.
Reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) have been increasingly used in asphalt mixtures. The use of RAP and RAS in asphalt mixtures not only reduces the consumption of virgin materials, conserves energy, and protects the environment but also improves the rutting resistance of asphalt pavements. However, as more recycled materials are used in asphalt mixtures, there is increasing concern over their potential negative effects on the mix cracking resistance. To improve the cracking resistance of asphalt mixtures with high RAP/RAS contents, one of the approaches considered is using recycling agents to potentially restore performance properties of the aged binder. This project was conducted to evaluate the effect of a recycling agent (RA), known as Hydrogreen, on the long-term field performance of high RAP and RAS mixes. The field study consisted of three test sections, each constructed by placing a dense-graded surface lift at a depth of 4.5 cm (1.75 in.) on SR 7 near Harrisonville, Missouri, in August 2013. The three mixes placed in the three test sections included: (1) a control mix containing 30% RAP using an SBS-modified PG 70-22 binder with no RA; (2) a 40% RAP mix using the same PG 70-22 binder with RA; and (3) a 25% RAP and 5% RAS mix using a neat PG 64-22 with RA. This paper presents data collected during the construction of the test sections, laboratory performance testing results, and early field performance. The research results showed that the recycling agent could be used in the 40% RAP and 25% RAP and 5% RAS mixes to achieve similar construction quality, laboratory performance, and early field performance to the 30% RAP control mix. As these sections are still in service, it is recommended that they continue to be monitored in order to evaluate their long-term performance.
With the increasing environmental considerations and rising costs of construction materials, reclaimed asphalt pavement (RAP) has been frequently added into asphalt paving mixtures during pavement construction. Many studies have been conducted with regard to the study of reclaimed unmodified asphalt pavement, but the reclaimed SBS modified asphalt pavement is still unknown. In this study, the effects of RAP and rejuvenating agent on the performance were studied. The moisture susceptibility, rutting resistance, dynamic modulus, low temperature anti cracking performance and fatigue was tested. Furthermore, in order to better understand the effects of RAP and rejuvenating agent, the control asphalt mixture was measured using the same methods. The results indicated that the asphalt mixture incorporating reclaimed SBS modified asphalt pavement with better moisture susceptibility, rutting resistance, dynamic modulus, low temperature anti cracking performance and fatigue resistance was obtained by blending new SBS modified asphalt binder and rejuvenating agent. Thus, the rejuvenating agent will benefit the effort of preparing more sustainable asphalt pavement containing RAP.
This study was focused on evaluating the feasibility of using minimally processed reclaimed asphalt pavement (RAP) as aggregate replacement in concrete pavements. A statistical experimental design procedure (response surface methodology) was used to investigate the effects of key mixture parameters on concrete responses. The response surfaces generated from this analysis adequately characterized the behavior of these concrete mixtures, and were ultimately used to develop optimum mixtures to meet varying performance criteria. In laboratory tests, the optimum mixtures performed well and as predicted, thus validating the feasibility of using RAP in this application and this mixture design methodology.
Reclaimed asphalt pavement (RAP) is a granular composite geomaterial that is highly reactive to the environment under normal atmospheric conditions. The binder aging processes that contribute to pavement deterioration do not stop upon reclamation. Here we report on the results of conventional and a novel RAP characterization test. RAP binder content has been observed to increase as RAP-particle size decreases. A simple analytical model is proposed to explain the results. Binder properties also change as a function of RAP-particle size. A simple thermomechanical test developed as part of this study shows differences in the temperature-dependent deformation of RAP particles of different sizes. These results evidence qualitative differences in binder viscosity, which can be attributed to RAP-binder aging.
Steel furnace slag (SFS) is an industrial by-product that is used as an abrasion-resistant aggregate in asphalt pavement surfaces. However, SFS has found limited application in concrete pavements because of its potential for expansion from hydration of the free calcium and magnesium oxides present in the slag. This study investigated the application of asphalt-coated SFS aggregates, i.e., coarse fractionated reclaimed asphalt pavement (FRAP), as an aggregate in concrete. Autoclave expansion testing of SFS FRAP samples and chemical analyses revealed that the SFS FRAP contains residual free calcium oxide and therefore has the potential to expand, although the presence of the asphalt coating reduced the overall expansion magnitude. The performance of SFS FRAP in concrete at 20% and 50% replacements was similar to concrete with unexpansive dolomite FRAP in terms of strength and fracture properties, though the SFS FRAP may cause higher shrinkage strains and reduced freeze/thaw durability. Therefore, application of SFS FRAP with low autoclave expansion, but available free oxides should be limited for use in concrete but may be suitable for nonstructural applications or temporary roads. With further standardized expansion testing, SFS FRAP may be suitable for use as an unbound foundation material or again as an aggregate in a bound asphalt layer.
A ternary-blend concrete (65% cement, 25% slag, and 10% fly ash) containing fractionated reclaimed asphalt pavement (FRAP) as a partial replacement (0, 20, 35, and 50%) for coarse aggregate was investigated through a comprehensive laboratory testing program. With increasing FRAP replacement, the concrete workability increased, unit weight decreased, and air content was mainly unaffected. The source of the measured strength and modulus reductions was linked to the interface between the FRAP particle and the paste. The incorporation of FRAP did not significantly impact the concrete free drying shrinkage but did reduce the restrained ring shrinkage strains. The freezing-and-thawing durability was acceptable for all tested FRAP contents. Fracture results indicated that FRAP addition did not statistically affect the initial or total fracture energy of the concrete. Mixtures containing up to 50% coarse FRAP may be used in concrete pavement and still produce acceptable fresh and hardened properties.
The recycling of reclaimed asphalt pavement (RAP) helps road authorities to achieve their goal of a sustainable road transport system by reducing waste production and resources consumption. The environmental and economic benefits of using RAP in hot mix asphalt (HMA) applications could be pushed up to the limit, by producing totally recycled HMAs (100% RAP), but the performance of this alternative must be satisfactory. In fact, these mixtures could possibly present problems of workability and durability, higher binder aging and low fatigue cracking resistance. Thus, the objective of this study is to determine if totally recycled HMA mixtures could be a good solution for road paving, by evaluating the merit of some rejuvenator agents (commercial product; used engine oil) in improving the aged binders’ properties and the recycled mixture performance. Several binder samples were prepared with the mentioned rejuvenators and characterized (Pen, R&B and dynamic viscosity), in order to select the best rejuvenator contents. The production temperatures of the corresponding recycled mixtures were evaluated based on their workability. Totally recycled HMAs were produced with the best previously observed combinations, and their performance (water sensitivity, rutting resistance, stiffness, fatigue resistance, binder aging) was assessed. The main conclusion of this study is that totally recycled HMAs can be a good alternative for road paving, especially if rejuvenator agents are used to reduce their production temperature and to improve their performance.
The paper presents a laboratory study on the properties of ordinary Portland cement (OPC) concrete made with reclaimed asphalt pavement (RAP) to substitute natural aggregate. RAP aggregates were incorporated in concrete on the basis of maximum packing of the particles to provide a mixture with minium voids and thus optimum performance. Concretes were made with various combinations of natural and reclaimed aggregates. The resultant mixtures were:oa)control mixture using natural sand and natural gravel.b)mixture containing reclaimed coarse aggregate and reclaimed fine aggregate.c)mixture containing reclaimed coarse aggregate and natural sand.d)mixture containing reclaimed coarse aggregate and natural sand where 30% of the ordinary Portland cement was substituted with fly ash (FA). The weight composition and water/binder ratio was the same for all the mixtures. The results of the study show that RAP aggregates reduce the compressive and tensile strength of concrete and that the reduction is proportional to the percentage of RAP used. Fine and coarse RAP cause more reduction than coarse RAP and sand. Of the mixtures containing RAP, the use of coarse RAP aggregate with OPC or OPC+FA did not affect the engineering properties of concrete, however, the performance properties were much improved with the use of fly ash as indicated by the measurements of porosity and permeability. The RAP concrete mixtures exhibited enhanced ductility and high strain capacity when compared to the control concrete mixture. These improved properties can be useful for the use of RAP aggregate concrete in the construction of road bases and sub-bases. The material is also potentially of use for all non-structural purposes.
Mixture design of six asphalt mixtures containing Reclaimed Asphalt Pavement (RAP) were evaluated by using a mechanistic-empirical approach. The testing methodology involved determination of the key mechanical properties and durability of wearing course and base course materials containing RAP at three different levels of addition (i.e. 10%, 30% and 50%), manufactured to a supplied specification, and the rheological properties of binder used in, and recovered from, these materials. In order to optimise both rutting and fatigue resistance, the recycled mixtures were manufactured by using 80/100pen virgin bitumen (which is one grade softer than the 60/70pen bitumen conventionally used for the respective parent asphalt materials), with or without added rejuvenating oil. This paper demonstrates that the asphalt mixtures containing RAP performed at least similar to, or better than, that of conventional asphalt materials.
This research examines how the addition of recycled asphalt pavement (RAP) changes the volumetric and mechanistic properties of asphalt mixtures. A Superpave (R) 19-mm mixture containing 0% RAP was the control for evaluating properties of mixes containing 15%, 25%, and 40% RAP. Two types of RAP were evaluated: a processed RAP and an unprocessed RAP (grindings). Testing included dynamic modulus in tension and compression, creep compliance in compression, and creep flow in compression. Dynamic modulus and creep compliance master curves were constructed with the use of the time-temperature superposition principle to describe the behavior of each mix over a range of temperatures. The voids in mineral aggregate (VMA) and voids filled with asphalt (VFA) of the RAP mixtures increased at the 25% and 40% levels, and there was also an influence of preheating time on the volumetric properties. The dynamic modulus of the processed RAP mixtures increased from the control to 15% RAP level, but the 25% and 40% RAP mixtures had dynamic modulus curves similar to that of the control mixture in both tension and compression. The creep compliance curves showed similar trends. A combination of gradation, asphalt content, and volumetric properties is likely the cause of these trends.
Road rehabilitation and reconstruction generate large supplies of reclaimed asphalt pavement (RAP) aggregate, and recycling into asphalt paving mixtures is the predominant application. Cement kiln dust (CKD), also known as cement bypass dust, is a by-product material generated during production of portland cement. In Oman, where recycling of pavement materials is not practiced, a first attempt was made at combining two by-product materials for use in road construction. Conservation of natural resources and preservation of the environment are two benefits that could be gained by reusing waste materials. The potential use in road bases of CKD-stabilized RAP and RAP with virgin aggregate mixtures was investigated. Physical, compaction, and unconfined compressive strength tests were conducted on RAP and virgin aggregate blends of 100% to 0%, 90% to 10%, 80% to 20%, and 0% to 100%. Samples were prepared using CKD at 0%, 3%, 5%, 7%, 10%, 15%, and 20% and were cured for 3, 7, and 28 days in plastic bags at room temperature. Results indicate that the maximum dry density and unconfined compressive strength of RAP generally increase with addition of virgin aggregate and CKD. The moisture content-dry density curves for CKD-stabilized RAP aggregate mixtures did not show a distinctive peak similar to that of the 100% virgin aggregate blend. Longer curing periods will produce higher strength values. CKD content of 15% seems to be the optimum for achieving maximum strength.
Recycling of pavement materials has become a viable alternative to be considered in road maintenance and rehabilitation. Conservation of resources, preservation of the environment, and retention of existing highway geometries are some of the benefits obtained by reusing pavement materials. In the United States of America, more than 50 million tons (45.36 million Mg) of asphalt paving material are milled annually; recycling into new asphalt paving mixtures is the predominant application. However, large quantities of reclaimed asphalt pavement (RAP) aggregate remain unutilized and further uses should be explored. In the Sultanate of Oman, recycling of pavement materials is not practiced; this study presents a first attempt at evaluating RAP aggregate. The reuse of RAP aggregate could be economically attractive in Oman because certain regions of the country experience virgin aggregate shortage. Furthermore, rehabilitation of the road network would provide a valuable resource to be considered in highway construction. A laboratory evaluation of RAP and RAP-virgin aggregate mixtures as road base and subbase materials is described here. Physical, compaction, and California bearing ratio tests were conducted on the following RAP/virgin aggregate blends: 100/0, 80/20, 60/40, 40/60, 20/80, and 0/100 percent. Initial results indicate that RAP could be expected to replace virgin aggregate in the pavement subbase structure with satisfactory results if the RAP material were mixed with virgin aggregate. Best results were obtained for the 60/40, 40/60, 20/80, and 0/100 percent RAP/virgin aggregate blends. Higher dry density and CBR values are obtained as virgin aggregate content is increased. Based on a comparison with standard paving materials used in the Sultanate of Oman roads, the stabilized RAP material appears to be able to function as well as a conventional subbase material. However, only minimal use of RAP (about 10 percent) can be expected in road bases.
Construction of shoulders using untreated reclaimed asphalt pavement (UNRAP) represents a new construction technique for Florida Department of Transportation (FDOT) and other DOTs throughout the country. The objective of this study was to provide practical guidelines that can be used in constructing shoulder base courses with UNRAP material. Field and laboratory tests were performed to determine the physical and mechanical properties of UNRAP material. The results suggest the UNRAP material is well graded and its maximum dry density is comparable to those of other conventional granular materials. However, the optimum moisture content for UNRAP is much lower than that for conventional granular materials. The in-place strength of UNRAP base, as postulated from the Dynaflect test results, is on the order of 70-85% of the strength of the limerock base. The use of UNRAP base in constructing paved shoulders was found to be an economically and technically feasible alternative to traditional limerock. Additional theoretical and experimental studies as well as new test procedures to assess strength characteristics of UNRAP are warranted.
In many countries there is a trend to recycle wastes obtained during pavement maintenance or reconstruction, and to forbid the landfill of these products. Thus, in some circumstances it can be tempting to use reclaimed asphalt pavement (RAP) in new hydraulic concrete mixtures. This paper presents experimental data and modelling about the effect of RAP incorporation on cement concrete mechanical properties (compressive strength, tensile strengths and E-modulus). All these properties tend to decrease with the rate of RAP dosage, and with temperature. Then attempts are made to adapt LCPC mix-design models to these innovative concretes. Two alternative hypotheses are evaluated. In the first one, RAP aggregate is viewed as composite particles playing the role of an homogenous aggregate having lower bond, strength and E-modulus as compared to normal aggregate. In the second one, the bitumen phase is assumed to be finely dispersed within the cement paste, acting as a supplementary dosage of water (or air). According to the simulations, the second hypothesis is the best one. This finding extends the scope of application of modern mix-design methods, and will help in using RAP in cement concrete, for the technical, economical and environmental benefit of the road community.
In developing countries without the availability of reliable pavement management systems, recycling techniques may offer the best alternative for pavement structural rehabilitation. However, for many government officials and contractors there is a clear understanding of the technical advantages of recycling but not a clear perspective of cost saving. Since cost is a relative value among different regions of any country the following work makes an energy analysis of the construction process of the three different rehabilitation techniques available in Chile. Three different structural pavement rehabilitation alternatives were studied and compared using an energy consumption methodology:•Asphalt overlay;•Reconstruction;•Cold in place recycling with foamed asphalt.The methodology considers different project scenarios by combining expected traffic and soil support values. For each rehabilitation technique and scenario, the construction processes were analyzed and the design layers were transformed to equivalent energy units (MJ/m2).Results show that cold in place recycling utilizes the lowest amount of energy compared with reconstruction or an asphalt overlay in all the scenarios studied, producing more differences when rehabilitating roads for less trafficked roads. The study also concludes that aggregate haulage distance is the most sensitive factor on total energy consumption when comparing the three alternatives.
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