Science topic

Asphalt - Science topic

Explore the latest questions and answers in Asphalt, and find Asphalt experts.
Questions related to Asphalt
  • asked a question related to Asphalt
Question
3 answers
The cantabro test is generally used in asphalt mixtures, but I would like to open the discussion of its main applications, and variables that could influence its results.
Relevant answer
Answer
Cantabro test is a simple accelerated test method to assess the material loss in compacted pavement mixtures (HMA, CMA, Porous, etc.) due to abrasive action. The test results indirectly indicates the adhesion and cohesion in the mixture. The test is simple and can easily differentiate the effect of density, porosity, polymeric additives, compaction effort, etc. The test results are influenced by initial condition of the test specimens, number and speed of revolution, test duration, number of test specimens (Generally 3 Nos.), modifications in the mixtures.
  • asked a question related to Asphalt
Question
1 answer
Software preferable for analyzing the effect of additives on moisture susceptibility of asphalt pavement based on aashto t283, retained stability and water boiling results
Relevant answer
Answer
Do you have the results and need software to analyze the results (such as finding a relationship between two parameters)? If this is the questions, then SPSS is useful
  • asked a question related to Asphalt
Question
3 answers
Dear Researchers
Suppose I have several asphalt mixes with different temperatures (each mix has a different temperature, ranging from 25 to 100 C). Could I mix them together to produce one large sample and test the mechanical properties of the large sample? Or do I need to keep the temperature of all samples at the same value before mixing them?
Thank you
Relevant answer
Answer
Thank you Doctor
G Ali Mansoori
  • asked a question related to Asphalt
Question
1 answer
As we know, the thermal stress is produced when the surface layer suffers from the constraints of base layer and the boundary conditions of pavement. Many researches focus on the thermal cracking model of asphalt surface layer itself, and also some focus on the thermal cracking spaces model with considering the constraints of base layer. However, if the constraints of boundary exists, the restraint function of base layer will be weakened. Thus, here is the question, which constraints cause the thermal stress first?
Relevant answer
Answer
G'day
Not sure that I've thought too much about this and how to model it! However, a practical observation is that where we have white thermo-plastic line marking on asphalt surfacing, we often see cracking along the edge of the line marking. We have always assumed that this is due to the different expansion properties of the white paint and the asphalt. Thermo-plastic is about 2mm to 3mm thick and well bonded to the asphalt so some differential expansion is likely to be occurring.
Regards
  • asked a question related to Asphalt
Question
13 answers
As asphalt has various components, how do we create a topology for asphalt.?
Relevant answer
  • asked a question related to Asphalt
  • asked a question related to Asphalt
Question
2 answers
I have not found too much information on emulsion-prepared mastics.
Optimal preparation procedure (mechanical or manual mixer)?
Water needed for mixing with high filler %?
Necessary curing?
Filler/asphalt ratios as in traditional mastics?
Thanks
Relevant answer
Answer
Dear Dr. Pablo Orosa ,
I suggest you to have a look at the following, interesting reference:
My best regards, Amir Beketov.
  • asked a question related to Asphalt
Question
3 answers
What is asphalt Mastic Theory /Filler Theory/adsorption theory?
Can you provide relevant paper
Relevant answer
Answer
This topic is extremely broad but also critical for the macroscopic behaviour of asphalt. Professors Yiqiu Tan and Meng Guo have a high-quality set of articles on the bitumen–filler interaction including the theoretical background. You might also find the following one useful (especially see the discussion section): .
  • asked a question related to Asphalt
Question
8 answers
I am curious to know if there is a way to observe in real-time microcrack formation and healing in asphalt binders. SEM electron beams seem to have sometimes strong enough to melt the binder and flow and may not be able to capture the actual healing.
Relevant answer
Answer
This is quite a challenging objective because the cracking the healing are both temporal processes, while the most reliable methods for the observation of asphalt microstructure are time consuming. Of coarse, the X-ray tomography (or some other tomographic technique) would provide the most detailed information. However, to obtain high quality tomograms is time consuming (taking up to several hours). Moreover, to catch the finest microcracks the resolution (i.e. effective voxel size) needs to be as high as possible, which requires a significant reduction of the specimen size. If you want to evaluate this simultaneously during the process of cracking/healing, obtaining crisp tomograms in reasonably short time intervals is practically impossible.
An alternative to speed the measurement up would be to use a simple X-ray radiography on specially designed thin specimens. However, although this would enable to you observe the crack propagation, you would need to develop the entire mechanical loading setup.
If the visual observation (imaging) is not the priority for you, there are other indirect approaches like those based on ultrasound, acoustic emission, microscopic techniques with special loading stages, etc.
Nevertheless, if characterising the internal microstructural development of a specimen is not the critical priority for you and observing these processes on the surface would be sufficient, by far the best approach would be to use digital image correlation (DIC). With the DIC you can easily overcome the issue of temporal resolution Besides the characterisation of crack length/depts, you can acquire also deformation maps and many other things. As a starting point I recommend you the following articles: , .
  • asked a question related to Asphalt
Question
3 answers
I designed a multilayer model of flexible pavement with Geocell in Base layer, but it is not showing significant difference in deformation with and without Geocell in PLAXIS 3D.
Young`s modulus (E) and thickness value for different layers are:
Asphalt (BC + DBM)- 2800MPa & 190mm thick
Granular Layer- 400MPa & 510mm thick
Subgrade Layer- 60MPa.
Poisson Ratio for all layer is 0.35
Relevant answer
Answer
For Plaxis, when modeling geosynthetic-reinforced foundations, you need to increase the phi by 5 degrees with respect to your unreinforced phi value (Wu et al., 2006, FWHA report). Then adjust your E values accordingly if you are using hardening soil model using Schanz et al. 1999 manual on HSM.
  • asked a question related to Asphalt
Question
10 answers
I have simulated 3 layers (asphalt concrete, base course, and subgrade) to determine the temperature in different depths of asphalt pavement. For this aim, a heat load is applied to the surface, however, after completing the job, I see heat is only at the top and in the first row of the mesh. Does anyone know what is the problem in the simulation?
Relevant answer
Answer
Simon Smith Thank you so much for your time and your help. I will revise the temperatures.
Best regards,
Mohsen
  • asked a question related to Asphalt
Question
1 answer
Cold recycling of asphalt pavements using bitumen emulsion
Relevant answer
Answer
This time is a sensitive factor. Operationally, it depends on the regulations of each country or institution. And in the laboratory, it depends on the design method used. There is no fixed time. There are those who do not wait between mixing and compaction, while studies can wait for hours.
But it gets even more complicated when active fillers, which react with water when mixed, are added to the mix. In these cases, even more time is usually needed.
  • asked a question related to Asphalt
Question
5 answers
Maybe it is related to the availability of materials used (RAP & WMA), skills/ awareness of RAP-WMA technology or guidelines in producing/ mixing asphalt mixes?
Relevant answer
Answer
  • asked a question related to Asphalt
Question
3 answers
I have not clearly found the maximum size of sand used in the mortar for the DSR to work properly.
0.5mm? 2mm? Any recommendations?
Thank you very much
Relevant answer
Answer
Hello Pablo Orosa ,
There are several possibilities about what is considered as asphalt mortar. If you follow the exact definition of sand then you need to stick to 2 mm. Some rough examples in literature are :
- the Dominant Aggregate Size Range–Interstitial Component (DASR-IC) approach: limit is 2.36 mm (#8 sieve)
- the Fine Aggregate Matrix (FAM) approach: 0.3 to 2.36 mm, depending on
the maximum aggregate size of the mixture
- In Europe studies typically use 0.5 mm.
Generally you have to keep in mind three aspects before selecting: the type of sample, the mixing compaction method and how powerful your DSR is. The larger the max sand grain the larger the sample you need to choose. Also, the larger the max sand grain the more stiff it becomes and then you need to apply some compaction effort and you need also a more powerful DSR to run the tests (again depending what you want to investigate).
My personal experience is with self-compacted asphalt mortars with max sand grain size of 0.5 mm.
  • asked a question related to Asphalt
Question
2 answers
Is the nature of the reaction of asphalt with the polymer alkylation reaction in the presence of Lewis acid or what?
Relevant answer
Answer
Rheological Behavior and Its Chemical Interpretation of Crumb Rubber Modified Asphalt Containing Warm-Mix Additives
Show all authors
Haopeng Wang, Xueyan Liu, Panos Apostolidis, ...
First Published July 27, 2018 Research Article 📷
Article information  📷
📷📷📷
Abstract The microstructure and chemical composition of asphalt binders have a significant effect on their rheological properties and, therefore, their performance as road paving binders. This study aims to investigate the effects of warm-mix asphalt (WMA) additives, organic type and chemical type, on the rheological properties and chemical internal structure of base asphalt and crumb rubber modified asphalt (CRMA). A set of dynamic shear rheometer (DSR) tests was conducted to obtain the rheological parameters (e.g., complex viscosity, complex modulus, phase angle) of asphalt binders. The flow activation energy was calculated from Arrhenius equation based on viscosity data to rank the thermal susceptibility. Black diagrams and master curves of complex modulus and phase angle were utilized to analyze the rheological properties. The molecular weight distributions of asphalt binders were inverted from the phase angle master curve to evaluate the molecular weight characteristics. It was found that the the addition of crumb rubber into base asphalt improves the rheological properties of enhanced modulus and elasticity. Organic and chemical types of WMA additives have different chemo-physical effects on both base asphalt and CRMA. Phase angle inversion method provides a powerful tool to monitor the molecular structure change and, therefore, the chemo-physical interactions of asphalt binders induced by modifications. Finally, there is a good correlation between flow activation energy and molecular weight.Recycling crumb rubber from end-of-life tires into asphalt paving has been applied for several decades for its tremendous economic and environmental benefits. It is reported that the incorporation of crumb rubber modifier (CRM) into asphalt binders can improve the overall performance of asphalt pavements (1, 2), such as improved aging and oxidation resistance, greater resistance to fatigue/thermal cracking and rutting, lower noise generation, higher skid resistance, and so forth. The above-improved performance of rubberized asphalt pavement relies on the interaction of CRM with asphalt. Depending on different interaction parameters (temperature, time and mixing rate, etc.), rubber-asphalt interaction is generally related to two mechanisms (3, 4): (a) swelling of CRM particles in asphalt matrix through absorbing the light aromatic oils of asphalt, and (b) degradation (devulcanization and depolymerization) of CRM through the release of its components into the liquid phase of asphalt.The improvement of the rheological properties of the rubberized asphalt binders has been observed after the interaction of CRM with asphalt (5). However, due to the high viscosity of rubberized binders, high mixing and compaction temperatures are required to achieve desirable workability and density of asphalt mixtures. In addition, the consequent high emissions and compromised work conditions during the construction process of rubberized asphalt pavement have been criticized (6). Warm-mix asphalt (WMA) technologies are developed to substantially decrease the production and placement temperatures of hot-mix asphalt (HMA) through mechanisms of viscosity reduction and lubricity enhancement (79). The coupling of WMA technology with rubberized asphalt is supposed to be a sustainable paving technology with the merits of energy conservation, environmental protection, performance optimization and durability extension (10). WMA products can be categorized into three main types (11): foaming processed, organic (wax-based) additives, and chemical additives. With the addition of new chemicals, the microstructure and molecular characteristics of original asphalt binders can be alternated. The different characteristics of WMA additives determine the different effects on the rheological properties of asphalt binder. It is vital to investigate the influence of WMA additives on the rheological behaviors and chemical structures of rubberized binders before applying them in the mixture level.Chemical Interpretation from Rheology Asphalt is commonly accepted as a multi-disperse colloidal system, where high molecular weight (MW) asphaltene micelles are peptized by resins in low molecular weight maltenes, with rheological behavior resembling that of a low-molecular-weight polymer (12). The chemical composition and microstructure of asphalt binder has a significant effect on the material rheological properties and, therefore, on its performance as a road paving binder.A large amount of research works has been done to link the chemical nature of asphalt with its physical behavior, and thus to explain the mechanical performance. Typically, the microstructure and composition of asphalt can be determined through classical chemical characterization techniques, such as atomic force microscopy (AFM) to obtain surface topography, gel permeation chromatography (GPC) to obtain molecular weight distribution, thermogravimetric analysis (TGA) for thermal analysis, Fourier transform infrared (FTIR) spectroscopy to identify functional groups, and so forth (13). However, these chemical characterization methods need exclusive instruments, special training, and complex sample preparation. More importantly, due to the chemo-physical complexity of certain asphalt products (modified or emulsified), it is not suitable to use all the above techniques in every case (14, 15). Recently, a few attempts were made to obtain the molecular weight distribution (MWD) and activation energy (Ea
) for the flow of asphalt through rheological tests.
Relationship between Rheology and Flow Activation Energy
Viscosity is a measure of material’s resistance to flow and deformation. The concept of the flow activation energy of asphalt describes the minimum energy barrier which asphalt molecules must overcome for flow to occur (16). It can be used to differentiate asphalt binders and to characterize the thermal susceptibility of the asphalt binders (17). The temperature dependence of the viscosity of asphalt can be described by an Arrhenius equation (Equation 1).
η∗=AeEa/RT
(1)
where A is a pre-exponential parameter, R is the universal gas constant (8.314 J/[mol·K]), Ea
is the activation energy (kJ/mol), T is temperature in degrees K, and η
is the complex viscosity at zero or low shear rate (Pa·s). The activation energy can be calculated based on known paired data of temperature and zero-shear or low-shear viscosity (18).
Since zero shear viscosity (ZSV) is a theoretical concept and it is impossible to measure the absolute value directly, various models were developed to extrapolate the ZSV value (19). However, it was found that highly modified asphalt binders exhibit extreme high viscosity gradients at low frequencies, resulting in unrealistically high ZSV values using model predictions (20). It was also found in this study that CRMA binders and wax-based additive modified binders yielded unpractical ZSV values. Therefore, the low shear viscosity at 0.01 rad/s was used as a replacement to calculate the activation energy. In addition, the Ea
values can also be obtained through fitting shift factors using the Arrhenius equation during the process of constructing master curves (21). Others reported similar Ea
values using a shift factor-based Arrhenius equation as the viscosity-based Arrhenius equation did (21, 22). This is mainly because different rheological parameters are interrelated.
Relationship between Rheology and Molecular Weight Distribution
It is well known that asphalt is composed of low (aromatic oils), medium (resins), and high (asphaltenes) molecular weight constituents and the incorporation of new additives (e.g., polymers and chemical surfactants) into base asphalt will inevitably change the proportions of these components. Consequently, the MWD alters due to the various interactions. Since MWD is associated with the internal structure as well as the structure-sensitive properties (e.g., rheological properties) of asphalt binders, comparing the MWDs of base and modified binders is a useful method to evaluate the chemo-physical interactions between base asphalts and additives. It is known that the linear viscoelastic parameters of polymer solutions and melts, as well as asphalt, are strong functions of molecular weight. Zanzotto et al. (23) inverted the fractional model of complex modulus to generate the MWD of regular and modified asphalt and compared with the MWDs obtained by GPC test. It was found that the MWDs calculated from rheological data are in good agreement with the corresponding GPC data. In subsequent research, Zanzotto et al. (14) found the phase angle to be more sensitive to molecular weight changes than the complex modulus. In addition, they noted that GPC is more sensitive to low molecular weights while the rheological inversion yields a higher resolution in a high molecular weight band. It is noticeable that solvents used to dilute asphalt in GPC test potentially change the microstructure of asphalt, resulting in an erroneous representation of the MWDs of the undiluted asphalt. On the other hand, in case of materials containing insoluble components (e.g., rubber) in common solvents, the use of the chromatographic method is not feasible. Considering the above two limitations of GPC tests for asphaltic materials, in terms of AR binders containing WMA chemicals, deducing MWDs from linear viscoelastic parameters seems a more promising alternative.
Before deriving the MWDs from the linear viscoelastic properties, two important definitions should be known, namely, differential molecular weight distribution (DMWD) and cumulative molecular weight distribution (CMWD). DMWD is a molecular weight distribution function (or a probability density function) of molecular weight. CMWD is an integral of DMWD from zero to a specified molecular weight. The relationship between DMWD and CMWD can be described using molecular weight as follows:
w(M)=dfc(M)dlogM
(2)
or
fc(M)=∫−∞logMw(M)dlogM
(3)
where M = molecular weight; w(M)
= molecular weight distribution function or probability density function, it represents the relative amount of different molecular weights; fc(M) = the cumulative weight fractions of molecules from zero up to a specified molecular weight (M
). Based on the double reptation mixing rule (24), the phase angle can be related to the MWD through the following relationship:
δ(ω)=∫0∞w(M′)c(M′,ω)dM
(4)
where δ(ω)
= phase angle as a function of angular frequency; w(M′) = weight distribution function; c(M′,ω)
= monodisperse phase angle of a relaxation unit. With the assumption that the monodisperse phase angle is proportional to the Heaviside step function H:
c(M′,ω)~1−H(M′−M)
(5)
Equation 5 explains that, at a given frequency, if the specified molecular weight (M
) is smaller than the corresponding molecular weight (M), it will relax and make no contribution to the viscoelastic phase angle (25). A simple power law was used to relate the molecular weight domain to the frequency domain (ω
= crossover frequency):
M=κωα
(6)
The calibrated values for constants in Equation 6 based on test data were logκ=2.544
, α=0.06768
at reference temperature of 0°C (14). Substituting Equations 5 and 6 into Equation 4, the following relationship can be obtained for normalized molecular weight:
δ(x)~∫0M=κ10−αxw(M′)dM
(7)
where x=logω
. Comparing Equations 3 and 7, it can be found that both cumulative weight fractions and phase angle are functions of molecular weight and there exists a link between cumulative weight fractions and phase angle in a logarithmic scale. Since phase angle is also a function of frequency, if the power law relationship between molecular weight and frequency is known, then the phase angle can be plotted as a function of molecular weight. Considering the constraint and boundary conditions of the cumulative weight fractions:
when M→0
, δ(M)=0, fc(M)=0
;
when M→∞
, δ(M)=90∘, fc(M)=1
.
The relationship between cumulative weight fractions and phase angle can be written as:
fc(M)=190δ(M)
(8)
Therefore, with the phase angle master curve and the calibration of Equation 6, the molecular weight distribution can be obtained through Equations 2 and 8.
Based on above derivations, one should note that rheological properties actually depend on the apparent MWDs that include the associations of various molecular weight constituents rather than on the MWDs of an individual molecule. Therefore, the MW obtained in this study means the apparent MWs of different molecular associations. Figure 1 summarizes the flow diagram of the steps and representative graphs involved in the conversion of linear viscoelastic data into an MWD, which is called the phase angle inversion method in this study.
📷
Figure 1. Flow chart of converting phase angle data to MWD data.
Objective
Based on above considerations, the main objectives of this study are:
  • to investigate the effects of WMA additives on the rheological properties of base asphalt and CRMA;
  • to obtain flow activation energies and molecular weight distributions (MWD) of asphalt binders based on rheological properties; and
  • to build up the potential relationship between flow activation energy and molecular weight.
Materials and Methods
Raw Materials
Base asphalt of 70/100 penetration grade commonly used in the Netherlands was provided by NYNAS. The SARA fractions of the base asphalt are 7% for saturates, 51% for aromatics, 22% for resins, and 20% for asphaltenes, respectively. The CRMs, supplied by RUMAL, were produced by ambient grinding of scrap truck tires. The CRMs have particle sizes ranging from 0 to 0.5 mm and consist of about 55% rubber, 30% carbon black, and 15% other impurities. Two types of typical non-foaming WMA additives, wax-based product W and chemical-based product C, were utilized in this study. Additive W is a synthetic microcrystalline wax that is free from sulfur and other impurities and Additive C is a liquid chemical package of products, such as surfactants, polymers, additives, anti-stripping agents, and so forth.
Binder Preparation
The CRMA was produced in the laboratory by blending 18% CRMs by the weight of base asphalt based on the previous studies (1) and trial mixing. Manual stirring for 5 min was applied to pre-distribute CRM in the base asphalt, then the blend was mixed using a Silverson high shear mixer at 180°C and 6000 rpm for 30 min. During the laboratory mixing process, the mixing head was immersed into the hot bitumen to avoid a vortex which may involve the potential oxygen. Each WMA additive was incorporated into both base asphalt and CRMA with the same dosage. The percentages of WMA additives W and C were 2.0% and 0.6%, which were determined based on manufacturers’ recommended dosage and preliminary tests. Therefore, a total of six types asphalt binders were prepared in this study, namely 70/100, 70/100-W, 70/100-C, CRMA, CRMA-W, and CRMA-C. To solely investigate the effect of WMA additives on the rheological properties of binders, all binder samples were tested in fresh states without artificial ageing.
Rheological Measurements
Dynamic shear rheometer (Anton Paar) was utilized to obtain the rheological parameters (complex shear modulus, phase angle and complex viscosity) of different asphalt binders. Frequency sweep tests were carried out from 0.01 to 100 rad/s over a temperature range of 10°C ∼ 50°C with an increment of 10°C. Before the frequency sweep tests, strain amplitude sweep tests were conducted to identify the linear viscoelastic (LVE) range of different binders and thus to guarantee that the frequency sweep tests were undertaken within the binder’s LVE region of response.
Results and Discussion
Complex Viscosity
Figure 2 plots the complex viscosities of different asphalt binders through dynamic shear rheometer (DSR) measurements. Viscosities at various combinations of temperature and frequency showed similar trends and are, therefore, omitted here. It can be clearly seen that the viscosity is dependent on temperature and shear rate (frequency) which decreases as the temperature and/or frequency increases. Figure 2a shows that at 50°C, the base asphalt 70/100 with and without additive C both behave like Newtonian fluids, whose viscosities are almost independent of shear rates. In contrast, 70/100-W and all CRMA based binders exhibit non-Newtonian behaviors as the viscosities increase significantly as the shear rate decreases. It was also found that CRMA presents much higher viscosity than base asphalt.
📷
Figure 2. Complex viscosity of different binders versus (a) frequency at 50°C; (b) temperature at 0.01 rad/s.
The addition of chemical WMA additive has an insignificant effect on the viscosity of both base and CRMA binders at a certain shear rate. However, organic additive increases the viscosities of both base and CRMA binders significantly, which seems contradictory to the viscosity-reduction effect of wax-based additive W at high construction temperatures (26). It should be noted that additive W is a synthetic wax with high molecular hydrocarbon chains, and its melting point is around 90°C. Therefore, when tested at 50°C, additive W in asphalt binders will crystallize to form a lattice structure and, therefore, stiffen the binders. This phase transition characteristic of additive W also explains the improved deformation resistance of binders containing W at service temperatures. In addition, through comparing the slopes of complex viscosity versus temperature curves in Figure 2b, CRMA based binders and 70/100-W are less thermal susceptible than base binder 70/100.
From Rheology to Flow Activation Energy
Figure 3 presents the plot of logarithmic viscosity as the ordinate and reciprocal temperature as the abscissa. The Ea
values can be calculated based on the slope of ln (η*)-1/T curves with known R value according to Equation 1. As can be seen from Figure 3, the Ea value obtained for base asphalt is much higher than CRMA. Chemical-based additive C had insignificant effects on the activation energies of both base asphalt and CRMA, while wax-based additive W significantly decreased the activation energies. Activation energy can be used as an indicator for characterizing the thermal susceptibility of asphalt binders. Binders with lower activation energy were found to be less susceptible to the temperature changes (16, 17, 22). It should be emphasized that asphalt with higher Ea values do not necessarily mean it has higher viscosities. The calculated activation energy is highly dependent on the testing temperatures at which the material can be in different physical states. Jamshidi et al. (27) found Ea
values of asphalt blends at different phases (liquid, semiliquid, or solid) have opposite variation laws. Therefore, base asphalt, which has lower viscosity and higher activation energy, is more vulnerable to temperature change in the testing temperature range. From this point of view, the incorporation of CRM or additive W into base binders can improve the thermal susceptibility and deformation resistance within service temperature range, which coincides with the results of this study and previous research findings (26, 28).
📷
Figure 3. Temperature dependence of low-shear viscosity and calculation of activation energy.
Complex Modulus and Phase Angle
Black Diagram
A black diagram is a graph plotting complex shear modulus (G*) versus phase angle (δ) obtained from frequency sweep tests. This type of representation of test data eliminates the frequency and temperature and allows us to compare the viscoelastic response of bituminous materials without manipulating the raw data through time-temperature superposition principle. Generally, a black diagram is a useful tool in identifying possible discrepancies in test data, in verifying time-temperature equivalence and the thermo-rheological simplicity (29) of test samples, and in identifying different types of asphalt binders.
Figure 4 shows the representation of dynamic data in black space. It can be clearly seen that the circled data of CRMA binder is out of line compared with the rest of the data. This unconformity indicates instrument compliance errors at the particular temperatures and frequencies. After checking the broad raw data (e.g., shear strain, shear stress, torque), it was found that the torques corresponding to the circled data exceeded the maximum torque value (230 mN·m) of the DSR instrument. Therefore, these erroneous data were omitted before generating an accurate master curve. Except for the limited erroneous data, all the dynamic data produced smooth curves with slight scattering, indicating that the asphalt binders can be considered as thermo-rheologically simple materials. Compared with the base binder and 70/100-C, the addition of CRM and additive W to the base binders results in a shifting of the rheological data toward a lower phase angle (left), which means more elastic behaviors. This could be due to the polymer network of CRM and the crystalline structure of W formed within the asphalt matrix. Since different asphalt binders show different curve patterns in black space, the black diagram can also be used to differentiate materials. Unlike the base binder and 70/100-C, the black diagrams of all CRMA based binders show an inverse “S” pattern which is typically found in rubberized asphalt binders (30). The single modification by W changes the curve in black space into an inverse “C” pattern which is similar to that of SBS modified binder (29). At the phase angle of around 57°, there is evidence of phase transition of wax existing in the 70/100-W binder.
📷
Figure 4. Black diagram of different asphalt binders.
Master Curves of Complex Modulus and Phase Angle
Master curves are developed from the measured linear viscoelastic data using the time-temperature superposition principle at a reference temperature. In the present study, a modified Christensen-Anderson-Marasteanu (CAM) model (31) and Williams-Landel-Ferry (WLF) equation for shift factors fitting were used to develop complex modulus and phase angle master curves.
The master curves of complex modulus and phase angle at a reference temperature of 30°C are shown in Figure 5. Similar effects of CRM and WMA additives on the rheological properties were observed as previous analysis. From Figure 5a, all the modification of base asphalt increased the complex modulus at relatively low frequencies (elevated temperatures). However, the complex modulus of all binders merged together at high frequencies (low temperatures), where the base asphalt is relatively stiff and the rheological properties of modified binders are dominated by the characteristics of base asphalt. From Figure 5b, the modifications of base asphalt by CRM and additive W showed marked reductions in phase angle. The addition of additive C had insignificant effects on phase angle at relatively low frequencies but increased the phase angle at high frequencies due to the softening effect of the unique chemicals, which may be beneficial to the low-temperature performance. The presence of phase angle plateaus at intermediate frequencies for CRMA based binders indicates the three-dimensional rubber molecular networks or entanglements in the modified binders. The presence of a phase angle peak of 70/100-W again verifies the phase transition behavior of wax in the binder at intermediate frequencies (temperatures). To sum up, the CRM and additive W enhanced the stiffness and elasticity of base asphalt, which is derived from the physical cross-linking of molecules into the three-dimensional network and the unique crystalline lattice structure at the service temperature range, respectively.
📷
Figure 5. Master curve of (a) complex modulus and (b) phase angle at 30°C.
Furthermore, the phase angle master curves are less uniform than that of complex modulus. Measurements of phase angle are more sensitive to the chemical structure change and thus the modification of asphalt than the complex modulus. This finding has driven the work of linking phase angle to the chemical characteristics of asphaltic materials.
From Rheology to Molecular Weight Distribution
After obtaining the CMWD curve (fc(M)
versus logM), the DMWD curve (w(M)versus logM
) is determined by numerical differentiation according to Equation 2 with the help of mathematical tools to guarantee convergence. The DMWD curves of different asphalt binders are presented in Figure 6. In general, Figure 6 clearly shows the internal structural changes of modified asphalt binders. From Figure 6a, the phase angle inversion method gives similar number-average molecular weight of around 800 Da for base asphalt as reported in the literature using GPC test (14, 15, 32). This comparable result verifies the robustness of the inversion method.
📷
Figure 6. Molecular weight distribution comparisons between (a) base asphalt and warm-mix base binders, (b) CRMA and warm-mix CRMA binders, and (c) base asphalt and CRMA.
In terms of the effect of WMA additives on the MWDs of asphalt binders, it seems the MWD of base asphalt was not affected significantly by the additive C. The addition of W into base asphalt shifted the molecular weight to the heavier direction. It is known that additive W is a kind of microcrystalline wax with high molecular weight hydrocarbons in the range C40∼C120. Besides the molecular population of average MW (≈
1000 Da), a new molecular population of average MW (≈
3000 Da) came up due to the modification of W. Unlike the effects of WMA additives on base asphalt in Figure 6a, neither of the WMA additives changed the bimodal nature of MWDs of CRMA binders in Figure 6b. However, they both increased the relative amounts of molecular weights corresponding to the peak distribution. Comparing the MWDs of base asphalt and CRMA, it can be found that the unimodal MWD of base asphalt changed to bimodal MWD due to the interactions of CRM. This MWD change provides evidence that the internal structure of base asphalt was altered due to the addition of CRM. The large cross-linking molecules of rubber and the potential released polymer components from rubber make contributions to the increase in the average molecular weight of base asphalt.
In principle, the valley between two peaks of the MWDs should be smooth for real cases. The appearance of the sharpness in this case is mainly due to the inherent limitations of the phase angle master curve model and numerical differentiation error. Based on the above analysis, it can be concluded that the phase-angle inversion method has sufficient sensitivity to distinguish the structural changes of different binders and give comparable molecular weight distributions. However, the accuracy of this inverse method relies on the calibration of Equation 6 and phase angle master curve. More works need to be done on these two aspects to interpret the real molecular structure of asphaltic materials.
Relationship between Flow Activation Energy and Molecular Weight
The number-average molecular weight for each type of asphalt calculated from the MWD in Figure 6, as well as the flow activation energy, is summarized in Figure 7. It shows a strong linear relationship between molecular weight and flow activation energy. The flow activation energy decreases as the molecular weight increases at a constant shear rate in the tested temperature region. Contradictory results were also presented in the literature. García-Morales et al. (18) found that polymer addition leads to a reduction in Ea
, while Ait-Kadi et al. (22) found that the presence of polymer in asphalt results in an Ea increase. Also, Collins and Metzger (33) found that the flow activation energy based on viscosities at constant shear rate decreases as the molecular weight increases. They also found that the influence of molecular weight change on the activation energies obtained in the high temperature region is different from that in the low temperature range. Fundamentally, activation energy obtained from rheological tests relies on testing temperature, loading mode (constant shear strain rate or constant shear stress) and the material flow mechanism. The comparison of Ea
1.Lo Presti, D. Recycled Tyre Rubber Modified Bitumens for Road Asphalt Mixtures: A Literature Review. Construction and Building Materials, Vol. 49, 2013, pp. 863–881. Google Scholar | Crossref2.Wang, T., Xiao, F., Amirkhanian, S., Huang, W., Zheng, M. A Review on Low Temperature Performances of Rubberized Asphalt Materials. Construction and Building Materials, Vol. 145, 2017, pp. 483–505. Google Scholar | Crossref3.Abdelrahman, M. A., Carpenter, S. H. Mechanism of the interaction of asphalt cement with crumb rubber modifier. Transportation Research Record: Journal of the Transportation Research Board, 1999. 1661: 106–113. Google Scholar | SAGE Journals4.Ghavibazoo, A., Abdelrahman, M., Ragab, M. Mechanism of Crumb Rubber Modifier Dissolution into Asphalt Matrix and Its Effect on Final Physical Properties of Crumb Rubber-Modified Binder. Transportation Research Record: Journal of the Transportation Research Board, 2013. 2370: 92–101. Google Scholar | SAGE Journals5.Ragab, M., Abdelrahman, M., Ghavibazoo, A. Performance Enhancement of Crumb Rubber-Modified Asphalts Through Control of the Developed Internal Network Structure. Transportation Research Record: Journal of the Transportation Research Board, 2013. 2371: 96–104. Google Scholar | SAGE Journals6.Farshidi, F., Jones, D., Harvey, J. T. Warm-Mix Asphalt Study: Evaluation of Rubberized Hot- and Warm-Mix Asphalt with Respect to Emissions. Research Report: UCPRC-RR-2013-03. University of California Pavement Research Center, Davis, Calif., 2013. Google Scholar7.Baumgardner, G. L., Reinke, G. R. Binder Additives for Warm Mix Asphalt Technology. Journal of the Association of Asphalt Paving Technologists, No. 82, 2013, pp. 685–709. Google Scholar8.Bennert, T., Reinke, G., Mogawer, W., Mooney, K. Assessment of Workability and Compactability of Warm-Mix Asphalt. Transportation Research Record: Journal of the Transportation Research Board, 2010. 2180: 36–47. Google Scholar | SAGE Journals9.Hanz, A., Faheem, A., Mahmoud, E., Bahia, H. Measuring Effects of Warm-Mix Additives. Transportation Research Record: Journal of the Transportation Research Board, 2010. 2180: 85–92. Google Scholar | SAGE Journals10.Wang, H., Liu, X., Apostolidis, P., Scarpas, T. Review of Warm Mix Rubberized Asphalt Concrete: Towards a Sustainable Paving Technology. Journal of Cleaner Production, Vol. 177, 2018, pp. 302–314. Google Scholar | Crossref11.Rubio, M. C., Martínez, G., Baena, L., Moreno, F. Warm Mix Asphalt: An Overview. Journal of Cleaner Production, Vol. 24, 2012, pp. 76–84. Google Scholar | Crossref12.Lesueur, D. The Colloidal Structure of Bitumen: Consequences on the Rheology and on the Mechanisms of Bitumen Modification. Advances in Colloid and Interface Science, Vol. 145, No. 1–2, 2009, pp. 42–82. Google Scholar | Crossref13.Zofka, A., Chrysochoou, M., Yut, I., Johnston, C., Shaw, M., Sun, S.-P., Mahoney, J., Farquharson, S., Donahue, M. SHRP2 Report S2-R06B-RR-1: Evaluating Applications of Field Spectroscopy Devices to Fingerprint Commonly Used Construction Materials. Transportation Research Board of the National Academies, Washington, D.C., 2013. Google Scholar | Crossref14.Zanzotto, L., Stastna, J., Ho, S. Molecular Weight Distribution of Regular Asphalts From Dynamic Material Functions. Materials and Structures, Vol. 32, No. 3, 1999, pp. 224–229. Google Scholar | Crossref15.Themeli, A., Chailleux, E., Farcas, F., Chazallon, C., Migault, B. Molecular Weight Distribution of Asphaltic Paving Binders From Phase-Angle Measurements. Road Materials and Pavement Design, Vol. 16, No. sup1, 2015, pp. 228–244. Google Scholar | Crossref16.Salomon, D., Zhai, H. Ranking Asphalt Binders by Activation Energy For Flow. Journal of Applied Asphalt Binder Technology, Vol. 2, No. 2, 2002, pp. 52–60. Google Scholar17.Haider, S. W., Mirza, M. W., Thottempudi, A. K., Bari, J., Baladi, G. Y. Characterizing Temperature Susceptibility of Asphalt Binders Using Activation Energy for Flow. In Transportation and Development Institute Congress 2011: Integrated Transportation and Development for a Better Tomorrow, 2011, pp. 493–503. Google Scholar18.García-Morales, M., Partal, P., Navarro, F. J., Martínez-Boza, F., Gallegos, C., González, N., González, O., Muñoz, M. E. Viscous Properties and Microstructure of Recycled Eva Modified Bitumen. Fuel, Vol. 83, No. 1, 2004, pp. 31–38. Google Scholar | Crossref19.Biro, S., Gandhi, T., Amirkhanian, S. Determination of Zero Shear Viscosity of Warm Asphalt Binders. Construction and Building Materials, Vol. 23, No. 5, 2009, pp. 2080–2086. Google Scholar | Crossref20.De Visscher, J., Vanelstraete, A. Practical Test Methods for Measuring the Zero Shear Viscosity of Bituminous Binders. Materials and Structures, Vol. 37, No. 5, 2004, pp. 360–364. Google Scholar | Crossref21.Partal, P., Martınez-Boza, F., Conde, B., Gallegos, C. Rheological Characterisation of Synthetic Binders and Unmodified Bitumens. Fuel, Vol. 78, No. 1, 1999, pp. 1–10. Google Scholar | Crossref22.Ait-Kadi, A., Brahimi, B., Bousmina, M. Polymer Blends for Enhanced Asphalt Binders. Polymer Engineering & Science, Vol. 36, No. 12, 1996, pp. 1724–1733. Google Scholar | Crossref23.Zanzotto, L., Stastna, J., Ho, K. Characterization of Regular and Modified Bitumens Via Their Complex Modulus. Journal of Applied Polymer Science, Vol. 59, No. 12, 1996, pp. 1897–1905. Google Scholar | Crossref24.Tsenoglou, C. Molecular Weight Polydispersity Effects on the Viscoelasticity of Entangled Linear Polymers. Macromolecules, Vol. 24, No. 8, 1991, pp. 1762–1767. Google Scholar | Crossref25.Tuminello, W. H. Molecular Weight and Molecular Weight Distribution From Dynamic Measurements of Polymer Melts. Polymer Engineering & Science, Vol. 26, No. 19, 1986, pp. 1339–1347. Google Scholar | Crossref26.Jamshidi, A., Hamzah, M. O., You, Z. Performance of Warm Mix Asphalt containing Sasobit®: State-of-the-Art. Construction and Building Materials, Vol. 38, 2013, pp. 530–553. Google Scholar | Crossref27.Jamshidi, A., Hamzah, M. O., Shahadan, Z., Yahaya, A. S. Evaluation of the Rheological Properties and Activation Energy of Virgin and Recovered Asphalt Binder Blends. Journal of Materials in Civil Engineering, Vol. 27, No. 3, 2015. Google Scholar | Crossref28.Attia, M., Abdelrahman, M. Enhancing the Performance of Crumb Rubber-Modified Binders Through Varying the Interaction Conditions. International Journal of Pavement Engineering, Vol. 10, No. 6, 2009, pp. 423–434. Google Scholar | Crossref29.Airey, G. D. Use of Black Diagrams to Identify Inconsistencies in Rheological Data. Road Materials and Pavement Design, Vol. 3, No. 4, 2011, pp. 403–424. Google Scholar | Crossref30.Celauro, B., Celauro, C., Lo Presti, D., Bevilacqua, A. Definition of a Laboratory Optimization Protocol for Road Bitumen Improved with Recycled Tire Rubber. Construction and Building Materials, Vol. 37, 2012, pp. 562–572. Google Scholar | Crossref31.Bahia, H. U., Hanson, D. I., Zeng, M., Zhai, H., Khatri, M. A., Anderson, R. M. NCHRP Report 459: Characterization of Modified Asphalt Binders in Superpave Mix Design. Transportation Research Board of the National Academies, Washington D.C., 2001. Google Scholar32.Domin, M., Herod, A., Kandiyoti, R., Larsen, J. W., Lazaro, M., Li, S., Rahimi, P. A Comparative Study of Bitumen Molecular-Weight Distributions. Energy & Fuels, Vol. 13, No. 3, 1999, pp. 552–557. Google Scholar | Crossref33.Collins, E., Metzger, A. Polyvinylchloride Melt Rheology II—The Influence of Molecular Weight on Flow Activation Energy. Polymer Engineering & Science, Vol. 10, No. 2, 1970, pp. 57–65. Google Scholar | Crossrefvalues tested at different conditions may result in discrepant conclusions. The introductions of CRM and microcrystalline wax into base asphalt increase the molecular weight, and simultaneously provide cross linking and micro crystallization to the asphalt structure, resulting in a harden microstructure. This modification changes the rubbery plateau zone and the corresponding transition temperature between the terminal zone and the rubbery zone of master curves, and finally changes the flow mechanism in different temperature ranges. With limited experimental data, it is speculated that an increase in molecular weight has similar effects on flow activation energy as a decrease in transition temperature, which means decreasing activation energy (33). However, more fundamental work needs to be done to verify this phenomenon.📷Figure 7. Relationship between molecular weight and flow activation energy.Conclusions Warm-mix asphalt technology has been used in the rubberized asphalt paving industry to alleviate the issues of high construction temperature and high emissions stemming from the high viscosity of CRMA binders. Based on the rheological tests and their chemical interpretation, the following conclusions can be drawn: The incorporation of CRM into base asphalt dramatically increases the complex viscosity. It also improves the rheological properties of base asphalt with enhanced stiffness and elasticity provided by the cross-linking polymer network. Wax-based WMA additive increases the complex viscosity and complex modulus, and decreases the phase angle of asphalt due to the stiffening effect of the unique microcrystalline lattice structure at service temperatures. The chemical type of the additive has an insignificant effect on the rheological properties at the in-service temperatures. Asphalt binders modified by either CRM or wax-based additive have decreased flow activation energies, indicating lower thermal susceptibility. The phase-angle inversion method provides adequate and comparable molecular weight distributions, and this simply implemented method offers new perspectives in the interpretation of rheological data to monitor the change in the molecular structure of asphalt. Both CRM and the wax-based additive increased the average molecular weight of asphalt. The chemical-based additive had an insignificant effect on the molecular weight distribution of asphalt. There is a strong linear relationship between flow activation energy and molecular weight. The activation energy decreases as the molecular weight increases at a constant shear rate in the tested temperature region.For future research, more fundamental work needs to be done to further explain the mechanism of flow activation energy. GPC tests for various types of asphalt binders at both unaged and aged states should be conducted to produce a more accurate calibration equation for the phase-angle inversion method.Acknowledgements The authors acknowledge RUMAL for providing testing materials. The corresponding author would like to thank the financial support from China Scholarship Council.Author Contributions The authors confirm contribution to the paper as follows: study conception and design: Xueyan Liu, Tom Scarpas; data collection: Haopeng Wang; analysis and interpretation of results: Haopeng Wang, Panos Apostolidis; draft manuscript preparation: Haopeng Wang. All authors reviewed the results and approved the final version of the manuscript.The Standing Committee on Asphalt Binders (AFK20) peer-reviewed this paper (18-02433)References
View Abstract
View all > Similar Articles: Laboratory Comparison of Permanent Deformation and Fatigue Behavior of Neat, Polymer, and Rubbe... 📷Felipe F. Camargo and more...Transportation Research RecordMar 2019Evaluating Aging Properties of Crumb Rubber and Styrene–Butadiene–Styrene Modifie... 📷Koorosh Naderi and more...Transportation Research RecordJan 2014Investigation into the Oxidative Aging of Asphalt Binders 📷Yanlong Liang and more...Transportation Research RecordApr 2019
  • asked a question related to Asphalt
Question
9 answers
We know that the TERRATEST 5000 BLU is the Light Weight Deflectometer for dynamic plate load test to check compaction quality in earthworks and road constructions.
I am interested in is it possible to assess the strength of asphalt concrete pavements on highways and urban streets using the TERRATEST 5000 BLU (by definition of elastic deflection)?
Relevant answer
Answer
Dear Dr. Raximjon Soataliyev , Thanks for your helpful response!
  • asked a question related to Asphalt
Question
4 answers
I am trying to find ASR/ACR potential of micritic limestone when used as a coarse aggregate in asphalt and concrete.
Relevant answer
Answer
ASR is Alkalia - Silica Reactivity. It is a reaction between the surface of silica based rocks, and Portland Cement. Substituting about 20 % Fly Ash from coal fired power plants ( for the Portland Cement ) severely reduces this gel forming expansive reaction. Since Limestone does not have silica in it, and limestone is one of the main components of Portland Cement, there should be no Alkalia - Silica reaction. Limestone is Calcium Carbonate (Ca CO3), there is no SiO2.
  • asked a question related to Asphalt
Question
7 answers
If the asphalt is aging test alone, then the adhesion between asphalt after aging and aggregate is enhanced or weakened? Note: asphalt is aged and coated with aggregate, not aged after coated.
Relevant answer
Answer
Alphast and aggregate combination is generally use for flexible pavement. Pavement is subjected to repeated loadings ( Cyclic loadings) that induces fatigue on the pavement. The cyclic loadings are transferred through on the running layer as well as the base an sub-base and weakened the biding stress between asphalt and aggregate. Also, the heat generate by the contact tyres and pavement reduces the adhesion stress between aggregate and Alphast. Other chemical attack on pavement such as sulfate attack, alkali silica reaction (ASR), freeze and tawn deteriorate the adhesion between Alphast and aggregate.
  • asked a question related to Asphalt
Question
3 answers
The asphalt material is DBM VG40. I have determined its elastic modulus.
Relevant answer
Answer
You will need prony series data that you can include with TB and TBDATA commads, e.g.:
TB,PRONY,1, ,11,SHEAR
TBDATA ,1, 0.32528
TBDATA ,2, 0.01
...
  • asked a question related to Asphalt
Question
9 answers
Apart from considering surface texture for pavement maintenance purposes (Pavement condition evaluation etc.), is there any specification used for freshly constructed asphalt concrete (HMA) pavements? If so, what are the specified limits?
Relevant answer
Answer
Both testing are implemented for obtaining the coefficient of friction. The limits for that depends on the design speed and class of the roadway.
  • asked a question related to Asphalt
Question
3 answers
I want to use the static pressure method to make an asphalt specimen with a thickness of 50mm. how could I determine the required pressure strength?
Relevant answer
Answer
There is not a unified way of determining the optimum loading pattern that would result with the specimen structure perfectly corresponding to an on-site compacted pavement layer. Even the specifications usually adopt a single force-controlled or displacement-controlled methods to achieve this, which are always only an approximate solution.
However, I recommend you reading my following article on this subject where you can see how the static compaction procedure can be adjusted. If you want the force-controlled regime (as it could be assumed from your question), i suggest applying one of the target forces I used and only slightly extend or shorten the loading time.
Effect of compaction energy on physical and mechanical performance of bitumen emulsion mortar (https:/doi.org810.1617/s11527-014-0488-z)
However, if you do not have any previous experience with this way of compaction or with the internal structure of the material to achieve, the most straight-forward way would be to use a displacement-controlled regime (assuming that you have a servo-hydraulic machine to do that) and preset the target specimen height. Of course, the content of the mixture to compact would be calculated for the target void content.
  • asked a question related to Asphalt
Question
1 answer
FORTA-FI fiber is synthetic fiber (Aramid+ Polyolefin) that plays a major role in pavement performance. Polyolefin has a melting point of about 150ºC. Polyolefin appears to melt as the asphalt mix is mixed and compacted.
Does aramid only participate in strengthening the asphalt mixture?
What is the role of Polyolefin?
Thanks.
Relevant answer
Answer
In general, it has been shown that fibers influence the cracking process, providing ductility to the mixture and increasing the toughness. Similarly, fibers can work as a crack barrier that helps to prevent the formation and propagation of cracks. Furthermore, fibers can change the viscoelasticity of bituminous materials. In fact, some experimental results have shown that fibers can improve the rheological properties of asphalt binder over a wide range of loading frequencies and temperatures. Additionally, the fiber addition to the asphalt binder increases the softening point and viscosity and decreases the penetration point leading to an improvement in rutting resistance.
  • asked a question related to Asphalt
Question
10 answers
hello everyone,
i am working on simulating the cracking initiation and propagation using 2D XFEM by ABAQUS using monotonic and repeated loading.
I did two experimental test, fracture test for semi circular asphalt samples under three point load by using constant loading rate of 50/min, i got the load and displacement for test,
the second test, repeated load test by using low load cycle of 15% of fracture load, i got the load, displacement, and horizontal displacement for the SCB sample, the pic of samples and date are attached.
thank you for your time
Relevant answer
Answer
Thank you for your answer, already i had used power law and fractional time-dependent viscoelatic element to convert the creep data into relaxation modulus data. After that i have evaluate the data using abaqus.
  • asked a question related to Asphalt
Question
4 answers
Can the 'k' & 'c' values be derived analytically using the volumetric data( % aggregate,%binder, %air voids,% PP replaced) for a hot mix design?
Relevant answer
Answer
Elsewhere at this forum, I have suggested a mixture rule to estimate the thermal diffusivity for a composite after those of its components: https://www.researchgate.net/post/Why-the-thermal-diffusivity-of-polymer-composites-increases-with-filler-loading
  • asked a question related to Asphalt
Question
1 answer
In hot mix recycling, "organic rejuvenators" require lower dosages than "petroleum rejuvenators" to decrease the Performance Grade temperature (PG Temp.) of the hot recycled blend.
Relevant answer
Answer
It's a very good question. I do not have the answer. But what I have seen is that anyway the structural response would be greater with the oil-based rejuvenators. This article shows some results that we arrived at in a study:
  • asked a question related to Asphalt
Question
3 answers
Asphalt binder rheology field.
Relevant answer
Answer
And what about other solvents, such as 5-methyl furfural or 2-MeTHF or 2,5-dimethyl furan? Is there any literature on this?
  • asked a question related to Asphalt
Question
4 answers
We are testing binder linear amplitude Sweep
Instrument: Bohlin DSR II.
Asphalt material: ac-20 . Add to filler(conerete)
The results of our test are as shown in the figure, Strain from 0.1% to 30%,but when the strain exceeds 20%, the trend is weird .
Relevant answer
Answer
Due to the filler addition, typically your Linear Viscoelastic Limit (LVE) will reduce, and there could be two possibilities why your results look like this.
1) Due to the lower LVE limit, you are already reaching the Non linear limit. As the temperature decreases, then also your LVE limit will reduce. Therefore, if you see the 25°C curve, the curve starts to flatten out earlier (around 12%) but for 30°C it is closer to 17% or so.
2) The second possibility is that you have already reached the limit of your device. It cannot apply anymore torque because the upper limit is reached and your mastic is too stiff. You should check the status of the measurements if that is possible with this rheometer software.
  • asked a question related to Asphalt
Question
8 answers
The scientific approach is based on experimental tests, carried out on both the mix components (aggregates and bitumen) and porous asphalt. The main test used for the mix design is the Marshall test for stability. Such a test has been widely used in the pavement engineering community, and Asian and European countries; however, some countries, such as the United States, do not anymore rely on such an approach.
Relevant answer
Answer
Dear Dr. Abdulkhalik Al-Taei thanks for the suggested method ...
  • asked a question related to Asphalt
Question
5 answers
I want to enhance tge thermal performance of asphalt and concretes through adding chemicals, what are these chemicals and thier percentages in mixtures?
Relevant answer
Answer
I am not sure about asphalt but, a wide range of synthetic fibers or microencapsulated phase change material (PCMs) can have a direct effect on the thermophysical properties of concrete.
  • asked a question related to Asphalt
Question
6 answers
The difference between HMA and WMA:
Different authorities have defined different temperature ranges for these two types of mixtures. Based on the Illinois Asphalt Pavement Association Scholarship:
* A batch of HMA consists of aggregate and a viscous binding agent and is produced at a temperature range of about 300-350 ° F (149-177 °C).
** A batch of WMA is produced at a temperature range of 50-100 ° F (10-38°C) less than a batch of HMA.
Laboratory Procedural Differences:
HMA is typically produced between 275-350 ° F (135- 177°C); while WMA can be produced 100 degrees lower (38°C).
The HMA mixture should be poured at a specific temperature (greater than 10°C). The WMA mixture is sensitive to temperature changes because they are produced at a lower temperature. Are there special temperature conditions for WMA mixes that have a lower temperature range?
Thanks.
Relevant answer
Answer
HMA usually, it is produced at temperatures between (140-180 °C) and compacted at approximately (80-160 °C), while WMA is produced at temperatures ranging from (100-140 °C), and therefore produced at temperatures lower than the HMA by (20-40 °C).
  • asked a question related to Asphalt
Question
2 answers
i just want to know the interaction of PPA with asphalt binder and SBS modified asphalt binder??
Relevant answer
Answer
PPA works as a stiffener and cross-linker when used with SBS. Also PPA can improve the delayed elastic response of the SBS modified binder. Further, PPA is a hydrophilic material and easily attracts water. I personally experience from my study that Bitumen modified with higher % of PPA had a tendency to moisture susceptibility and loose strength.
  • asked a question related to Asphalt
Question
4 answers
Goal: Hi My project is about the feasibility of using pre-prepared hot and cold asphalt to repair the pavement around the manholes. I ask my dear researcher to help me if I have experience or information in this field?
Relevant answer
Answer
There is wide range of epoxies paste that handles such problem sufficiently. Make a parametric study with this!
  • asked a question related to Asphalt
Question
7 answers
for use in asphalt mix as a filler, we need to know the specific gravity in order to use it for air voids calculations 
Relevant answer
Answer
Zaid Abdul Zahra Mahdi How did you do it?
  • asked a question related to Asphalt
Question
6 answers
Usually RTFOT instrument is used to measure short term aging for asphaltic binders under standard conditions.
Under what standard conditions, can we use RTFOT instrument to measure long term aging.
Relevant answer
Answer
U have to extend the aging duration by using RTFO, and correlate the data to define how long it should be extended.
  • asked a question related to Asphalt
Question
5 answers
We have encountered this issue in an executive project
Relevant answer
Answer
Dear Ali
Thank you.
  • asked a question related to Asphalt
Question
4 answers
I am trying to simulate the moisture damage phenomena in asphalt mixture using abaqus. I am looking for some suggestions and guidelines to define the contact contact between aggregate and asphalt matrix in abaqus.
Relevant answer
Answer
Dear Towhidul Islam
The following dissertation may be useful to you:
Modeling Moisture-Induced Damage in Asphalt Concrete.
  • asked a question related to Asphalt
Question
4 answers
Hello Dear Sirs.
I'm looking for test method determine the frost resistance on freezing and thawing compacted asphalt concrete mixtures?
Best Regards
Munkhtuvshin
Relevant answer
Answer
Dear
I agree with Dr. Mazen Al-Kheetan and ِDr. Amara Loulizi.
To apply freeze-thaw cycles no particular method was suggested; however, there are many studies that have investigated (and recommended) different methods:
Pirmohammad, S., & Kiani, A. (2016). Effect of temperature variations on fracture
resistance of HMA mixtures under different loading modes. Materials and Structures, 49(9),3773-3784.
Pirmohammad, S., & Khanpour, M. (2020). Fracture strength of warm mix asphalt concretes modified with crumb rubber subjected to variable temperatures. Road Materials and Pavement Design, 1-19.
Fakhri, M., & Ahmadi, A. (2017). Evaluation of fracture resistance of asphalt mixes involving steel slag and RAP: Susceptibility to aging level and freeze and thaw cycles. Construction and Building Materials, 157, 748-756.
Fakhri, M., Siyadati, S. A., & Aliha, M. R. M. (2020). Impact of freeze–thaw cycles on low temperature mixed mode I/II cracking properties of water saturated hot mix asphalt: An experimental study. Construction and Building Materials, 261, 119939.
Goli, H., & Latifi, M. (2020). Evaluation of the effect of moisture on behavior of warm mix asphalt (WMA) mixtures containing recycled asphalt pavement (RAP). Construction and Building Materials, 247, 118526.
Karimi, M. M., Dehaghi, E. A., & Behnood, A. (2020). A Fracture-Based Approach to
Characterize Long-Term Performance of Asphalt Mixes under Moisture and Freeze-Thaw Conditions. Engineering Fracture Mechanics, 107418.
Kavussi, A., Karimi, M. M., & Dehaghi, E. A. (2020). Effect of moisture and freeze-thaw damage on microwave healing of asphalt mixes. Construction and Building Materials, 254, 119268.
  • asked a question related to Asphalt
Question
5 answers
Asphalt mixture durability is defined as the ability of compacted asphalt concrete to maintain. its structural integrity throughout its expected service life when exposed to the damaging effects of the environment and traffic loading. Asphalt mixture durability is one of several factors affecting pavement durability, which is defined as the ability of a pavement to retain a satisfactory level of performance over its expected service life without major maintenance.
-What are the indicators used to measure the durability for asphalt mixtures?
- How can improve the durability of asphalt mixtures?
- How can measure the durability of asphalt mixtures?
Relevant answer
Answer
The long-term ability of asphalt to heat, weather, traffic, and time (due to oxidation and other environmental factors) is often defined as its durability. Therefore, the tests related to these cases; can indicate the durability of the asphalt mixture:
Temperature susceptibility (SHARP tests: and some traditional methods: PI), moisture damage (AASHTO T283 or Modified Lottman test), rutting resistance (AASHTO T324, ...), low temperature cracking (AASHTO TP105, ... ).
Please refer to its standard for more details.
  • asked a question related to Asphalt
Question
4 answers
Scanning electron microscope
Relevant answer
Answer
You may type your request into science direct website. Then you are likely to get multiple answers to your request
  • asked a question related to Asphalt
Question
2 answers
Modification of the rheological properties of asphalt
Relevant answer
Answer
@ Dear Aldulaimi Hasanain
Thank you so much
  • asked a question related to Asphalt
Question
2 answers
What is the best method to extract the SBR modified bitumen? The SBR modified asphalt concrete mixture shows a lower passing percentage at 0.075 sieve compared to the control sample with no modification. Is this caused by the SBR binding the smaller sized material and preventing removal during the extraction process?
Relevant answer
Answer
If Viscometer with built-in temperature regulator may used.
Then it is easy to separate the two items.
  • asked a question related to Asphalt
Question
6 answers
Reaction between sulphur and asphalt
Relevant answer
Answer
Dear Ammar Hamdoon thanks for this interesting question. Actually, I'm not an expert in this field. However, you can find a few papers on this topic directly on RG, e.g.:
The second article is available as public full text on RG. Please find attached the first article.
  • asked a question related to Asphalt
Question
1 answer
I want to use Box-Behnken design (BBd) For reducing my tests.(4PBT/SCB/ITS/ITSM)
Relevant answer
Answer
Greetings there,
To be laconic, I think if u can go through it, it might help.
  • asked a question related to Asphalt
Question
5 answers
In the case of a polymeric additive to the asphaltic materials along with the presence of air oxidation, what is the nature of the reaction that will take place in this case?
Relevant answer
Answer
Dear Ammar Hamdoon, what is the nature of these polymeric wastes additives to guess any possible oxidation reaction with air. My Regards
  • asked a question related to Asphalt
Question
7 answers
First I want to choose some rejuvenators, then by analyzing FTIR results, choose the best one. what is the best considering index from results of FTIR test for better performance of rejuvenators(or oil) in capsules ?
Relevant answer
Answer
Hi Amin,
Carbonyls and sulfoxide functional groups in the FTIR spectrum of asphalt clearly determine the aging of asphalt. Determine the chemical aging index (CAI) for asphalt modified with each rejuvenator. Lower the CAI better the aging resistance.
Use the following as an example it could help you understand
  • asked a question related to Asphalt
Question
5 answers
I am looking for an accurate method to measure the water (moisture) content in an asphalt cement specimen (if any) using the thermo-gravimetric analyzer. Can anyone help me with such info?
Many Thanks!
Relevant answer
Answer
The most reliable method for measuring moisture in concrete is ASTM F-2170 method. I have attached the standard and some articles . I hope they would be useful.
  • asked a question related to Asphalt
Question
3 answers
Using the natural polymers in the asphalt modification
Relevant answer
Answer
Thank you very much
  • asked a question related to Asphalt
Question
5 answers
Is it possible to determine the dynamic modulus of HMA (SUPERPAVE) Mixtures by using the Universal Testing Machine (UTM) rather than the Simple Performance Tester (SPT)? If yes, then what calibration should be made? The specimens are 150 mm in diameter and 120 mm in hight, and they will not be subjected to a coring process.
Relevant answer
Answer
we do it... recipe in persian is attached.
  • asked a question related to Asphalt
Question
1 answer
Dear colleagues
Can someone help me with the parameters on the asphalt?
Let's simulate a street.
Relevant answer
Answer
Dr. Ladislau,
The asphalt is considered as a binding material, which helps to build asphalt mix by combining the different aggregates. It is a viscoelastic material showing drastic variation in its characteristics with a change in temperature. The mechanical, as well as chemical characteristics, are need to be defined before involving it in a pavement structure. The most common parameters are specific gravity, ductility, solubility, temperature susceptibility i.e. softening point, flash & fire point, etc. In an advanced analysis, rheological parameters are also required to be discussed. However, after preparing the asphalt mix, which is actually going to be utilized on the street, the strength and volumetric properties are essential to be determined.
  • asked a question related to Asphalt
Question
2 answers
If anyone have the following manuals, I will be grateful for if you send me on
AASHTO M320
Standard Specification for Performance-Graded Asphalt Binder
AASHTO R29
Standard Practice for Grading or Verifying the Performance Grade (PG) of an Asphalt Binder
Best regards
Relevant answer
Answer
AASHTO R29
  • asked a question related to Asphalt
Question
4 answers
Generally, semi-rigid pavement is used in China, composed of asphalt mixture surface layers and cement stabilized macadam base layers.
Relevant answer
Answer
In Libya, it is quiet similar to Tunisia. flexible pavement structure of a hot-mix asphalt layer over a granular base/sub base on top of a sandy-clayey sub grade soil is the most common type of pavement used despite the location and the traffic loading of the area. This practice is applied throughout the region.
By saying that, there are few circumstances where a thin layer of HMA is laid directly on the sub-grade where soil posses high strength.
  • asked a question related to Asphalt
Question
5 answers
What is the effect of addition of sulfur on the rheological properties of asphalt??
  • asked a question related to Asphalt
Question
1 answer
Dear All,
I am looking for hourly temperature data from any urban area for the following land covers. 1. grass cover. 2. lake/water bodies and 3. any pavement (concrete or asphalt).
Any information on such link to any journal/book/conference paper or website containing such data would be highly appreciated.
Relevant answer
Answer
Well, Chapter-15
Urban Climates is a must-read for students and scientists. From climatology to urban planning, it is very clear and complete, from concepts and processes to practical implementation and adaptation of cities to climate. It is illustrated with explicative diagrams of exceptional quality and many examples of this 'collection of microclimates' in various cities. Beyond the clear and rigorous overview of the physics of the urban atmosphere, Urban Climates offers a fantastic trip through the history of climate in cities around the world, from preindustrial cities and before to modern high-rise megacities.
Regards
  • asked a question related to Asphalt
Question
10 answers
I am looking for asphalt binder database containing DRS data for frequency or Temperature sweep of Unaged/RTFOT/PAV samples.
It could be modified or neat asphalt.
Can someone assist me with it or give me a link to where I can download an open open-source database?
Relevant answer
Answer
Ikenna this is the link, in this site there is a lot of bibliography related to the topic, you must spend some time to find what you need
  • asked a question related to Asphalt
Question
5 answers
Modified rheological properties of asphalt using different waste polymers at different partical sizes
Relevant answer
Answer
Dear all, yes there should be effect(s), now positive or négative this may dépends essentially on the compatibility and how is the strength (affinity) between the different components forming the compound. If you do a simple search within RG on questions related to asphalt, you will find a nice Book I have attached. My Regards
  • asked a question related to Asphalt
Question
4 answers
i am investigating the resilience of crumb rubber modified asphalt subballast under cyclic loading and extreme weather conditions in Nigeria.
i intend to use polypropylene granules to replace a small percentage of coarse aggregates in the mix.
Relevant answer
Answer
Dear Apeh, I recommend you to read the above recently published article (2020) which discusses the Mechanical Properties of Granular Tire Rubber used as Geomaterial either alone or mixed with Sand.
  • asked a question related to Asphalt
Question
2 answers
I just wanted to know hands on experiences regarding "Asphalt mixture" and its facts under any research which you have done so far.
Relevant answer
Answer
Dear Nadeesha Maduwanthi Hettiarachchi
We did some researches about asphalt mixtures. Asphalt mixture due to bitumen used in its matrix is a highly temperature depended material. At the high temperatures asphalt mixtures shows viscoelastic behavior and at a low temperatures asphalt mixtures shows a linear elastic behavior. At the low temperature conditions thermal cracking becomes to the main distress of asphalt mixtures. For preventing and minimizing cracks in asphalt mixtures researchers were used some modifiers (Polymers, Rubbers, Nanomaterials, Fibers, etc.). We used some type of nanomaterials (Nanotubes, Fe2O3, Al2O3, Montmorillonite, and Nano silica) and Fibers (Kenaf, Goat wool, Carbon, Glass, and Basalt) for improving the resistance of asphalt mixtures against crack occuring. Our Results showed that all type of modifiers increase the resistance of asphalt mixtures against low temperature cracking from 10% to 46%(based on type of modifier and optimum content of it). For more details about asphalt mixtures, I recommended you to read my works.
Regards.
  • asked a question related to Asphalt
Question
3 answers
Dear Colleagues
1) In the not very far future the transport fleet (and in fact the economy as a whole) is expected to move gradually to using gasoline to greener modes of transport – such as gas or electricity.
2) One of the outcomes of this change could possibly be sharp reduction in the use of gasoline, diesel fuel and as a result shut down or severe reduction in the activity of crude oil refineries.
3) Bitumen Binder is a residue of the refining of crude oil and as a result, sharp reduction in the refining process may result in severe shortage or probably even disappearance of this product.
4) In that respect we would like to have your answers on the following questions: a. Is the scenario described in 1-3 above relevant to your organization /country? b. If the answer to (a) above is positive – what are the actions taken by your country /organization to solve this problem? Thanks for your kind reply and cooperation
Relevant answer
Answer
Yes I accept the background information you provided but much of developing world an example of Nigeria has less than adequate road infrastructure and yet to have fully developed bituminous roads. So , I see this reality happening in developing countries in a distant future however, this may not be so for the first world countries as they already posses the technology and know how especially from recyled polyethylene waste materials as a replacement for bitumen and also concrete pavement technology which both adress the shortages that may occur as the world go green.
  • asked a question related to Asphalt
Question
8 answers
I came upon a real planning case, where a small street with a max speed of 30 km/h requires a complete makeover. The existing cobble stones can either be replaced by new ones or by asphalt. Some aspects beside, like historic ambience, noise emissions, or rainwater infiltration, which alternative would have which global warming potential (GWP), roughly estimated?
In my search for an answer I first found the publication of Santero and Horvath (2009) regarding the "Global warming potential of pavements". Following its citations I came across several publications about asphalt, concrete, and their respective innovations, also regarding their GWP. I even came across a paper by Lo Presti and D'Angelo (2017) regarding their "Review and comparison of freely-available tools for pavement carbon footprinting in Europe". However, I did not find any comparison between asphalt and cobblestone. Probably because the latter does not play a major role for today's streets. Suggestions are welcome!
Relevant answer
Answer
Did you consider old cobblestone from another, previously demolished roads? For this kind of low-traffic volume and low speed roads around historical sections of the city we often use old (e.g. granite) elements. Personally I think that cobblestone pavements (old or new) are more enviromental friendly than asphalt pavements mainly because life cycle of this surface will exceed asphalt one. You can surely find granite pavements older than 100 years and they rarely need any extended rehabilitation treatment. Ofc I'm talking about low speed and low traffic volume roads. Cobblestone also helps to reduce car speed without any additional dedicated solutions.
  • asked a question related to Asphalt
Question
1 answer
In estimating the texture distribution of asphalt mixtures, i have managed to use the discrete fourier transform on my idealized surface profile and obtained my spectral power density.
However the process of Transforming constant bandwidth spectral data to constant-percentage
bandwidth spectral data has proved challenging i would appreciate assistance in understanding and progressing from my current stage.
I have attached the excel sheet and an image of the formulas from ISO 13473-4
Relevant answer
Answer
the formula sheet
  • asked a question related to Asphalt
Question
4 answers
Attached, a question about pavement design by mechanical empirical approach that comparison between AASHTO 93 and KENPAVE.
AASHTO 93 design life : 20
KENPAVE design life : 9.8
Why does the huge difference occurs ?
Relevant answer
Answer
Agreed @Amjad Albayati
  • asked a question related to Asphalt
Question
5 answers
During winter on runway of airport appeared blisters. After study, most possibly reason of that are used deicers (potassium formate, sodium formate). Are there test methods, that could confirm or reject my argument?
Relevant answer
Answer
Polecam artykuł Pań: Danuta KOWALSKA, Agata MISZTAL ITWL "ZIMOWE UTRZYMANIE NAWIERZCHNI LOTNISKOWYCH A BEZPIECZEŃSTWO WYKONYWANIA OPERACJI LOTNICZYCH PRZEZ STATKI POWIETRZNE"
  • asked a question related to Asphalt
Question
4 answers
Has the recycled asphalt concrete (recycled RAP) a good behavior in fatigue? Have you any reference to me propose in this topic? Thank you
Relevant answer
Answer
  • asked a question related to Asphalt
Question
5 answers
Hi,
please help me with this question
I've been trying to model three-layer pavements (one rigid and one flexible) in Canada and I'm quite new to the design of pavements. My problem is the input. Do you have any suggestions as to where I can find the input data for pavements in Canada? I've been navigating the LTPP website, but it seems the data are not complete for the pavements. For instance, for one particular pavement, say SHRP_ID 0901, the input data are complete for all the layers but not for the Base Layer.
Thank you so much in advance!
Relevant answer
Answer
To model pavements with three layers (one rigid and one flexible) in Canada, it is necessary to collect this information from the design offices responsible for diagnosing and prospecting pavements affected by deterioration.
  • asked a question related to Asphalt
Question
1 answer
I am modelling a 3 point bending test of Asphalt Mixture beam . The beam is modeled as visco-elastic material . After peak load also the material gains strength as it ismodeled as visco elastic but I want to terminated the program once it reaches a yield point how to mention that in ABAQUS .
Please suggest some answers . thank you in advance
Relevant answer
Answer
One trick is is to do the simulation, control the yield criteria for material, Lets say maximum tensile stress, and monitor the max of tensile stress in your sample. Whenever the max tensile hit that critical yield point, your sample start yielding. You can use whatever criteria you want for yield stress. After this point, your simulation using visco elastic is not valid anymore.
You should be careful that this will be different than the maximum load, because yielding one point does not essentially means yielding the while sample. Typically, we are interested in maximum loading.
  • asked a question related to Asphalt
Question
2 answers
can anyone explain the chemistry between SBS and bitumen, if any sort of physical interactions happening between SBS molecules and bitumen, any literatures which conclusively ecxplains this phenomena??
Relevant answer
Answer
Look at the attached work.
Giacomo
  • asked a question related to Asphalt
Question
2 answers
I was working on a pavement model in ANSYS containing asphalt bottom layer with concrete slab panels on top of it. The slabs are tied to an asphalt shoulder at one side as well. The pavement is sitting on an elastic foundation and is subjected to wheel loads. After meshing has been done, I was trying to connect the adjacent slabs for load transfer between them, with springs in longitudinal and transverse direction in ANSYS. I need some idea on how can I do that so that the rigid body movement is restrained effectively when subjected to loads. I am attaching a screenshot of my model for your kind consideration.
Relevant answer
Dear Souvik Roy ,
First of all, if you are dealing with a symmetry geometries and boundary conditions, you may want to activate the "Weak Spring" option in "Analysis Setting" that is going to add a spring element automatically to your model and avoid rigid body motion. Since you did not say anything regarding the BCs, I can't say this is the solution for your problem.
If you want to apply the springs, then you need to follow these steps.
Add a "Connections" to your model in case you don't have one in your analysis. Then Under "Connections", insert "Spring". There are two option available for defining a spring which are Body-Body and Ground-Body options. In your case, I think that you need to use Ground-Body one. You can define the Ground side using Cartesian coordinate and on the other side you can select either point, line or surface from your geometry.
Since you mentioned that you want to put constrain longitudinally and laterally, then you need to apply two springs in those directions.
Hope this get you started.
  • asked a question related to Asphalt
Question
4 answers
Esteemed Researchers,
I have come across three approaches used by researchers for fabrication of asphalt mix specimens when they study modified asphalt binders with different modifier dosages (or different modifiers):
Approach 1: Determine the optimum asphalt content (OAC) for the mix with control (unmodified) asphalt binder, and use the same binder content while fabricating asphalt mix specimens with modified binders. Mix volumetrics (e.g. air voids) are kept constant for mixes with modified binders. This has the main advantage of avoiding binder content as a secondary variable when your interest is just to see how the different mixes perform under variable modifier dosages.
Approach 2: Determine the OAC for each binder obtained with different dosages of the modifier. This generally results in OAC values that are quite close (but not exactly the same) to the OAC obtained for control (unmodified) asphalt binder. But this approach introduces binder content as a secondary variable (even though the volumetrics are the same) when one is just interested to analyze the mix performance results as a function of modifier dosage. Hence, it becomes difficult to understand whether the observed trends are due to different modifier dosages or due to different binder contents.
Approach 3: Some researchers also suggest keeping a constant binder content by mix volume (instead of a constant binder content by weight of the mix). However, this approach will lead to difference in the binder content by weight of the mix. Also note that expressing binder content by weight is the most common way of specifying binder content in field and during mix design. Hence, this approach is quite rarely used in the literature.
What would you recommend as the 'correct' approach? Will really appreciate your advice!
Thank you for your valuable time!
Relevant answer
Answer
I suggest that you use mixture design to design the experiment and use optimisation to get the optimum mix of the materials, thanks.
  • asked a question related to Asphalt
Question
4 answers
In the reason for investigating the composite pavement performance in the laboratory, we prepare samples of asphalt overlay portland cement concrete in one mold, so we find some difficulties with how bonding between those two layers.
Relevant answer
Answer
there are different type of epoxy that supplied in two packs Resin and Hardener
Nitobond TM epoxy which is manufactured by (Fosroc International Limited Company) is good for bonding
  • asked a question related to Asphalt
Question
2 answers
How to define the loading and recovery time for the Creep-Recovery Test on an asphalt mixture ?
Creep-Recovery Test at varying stress levels and test temperature are perform to determine the linear and nonlinear viscoelastic characteristics of an asphalt mixture. During this experiment the stress is applied for a particular period of time [loading time (t)] and is removed after a certain time [recovery time] as shown in the attached figure.
Relevant answer