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This paper deals with the characterization of dry sand-rubber tire shred mixtures to find shear strength and dynamic properties. A series of ordinary triaxial shear tests, direct shear tests and dynamic triaxial tests were performed on dense dry sand-rubber tire shred mixtures for various rubber replacement levels such as 0, 10, 30, 50 and 100% by weight. The effects of rubber content, confining pressures and rates of shearing on the angle of internal friction of the mixtures were investigated. Also, the influence of rubber content and the rate of horizontal displacement on the volumetric strain is presented. In addition, this paper proposes an appropriate method to find the angle of repose of dry sand-rubber tire shred mixtures. The angle of repose of the mixtures is compared with the angles of internal friction obtained from triaxial shear and direct shear tests. Finally, the effects of saturation, rubber content, axial strain, frequency and number of cycles of loading on the strain-dependent stiffness and damping properties of these mixtures were studied.
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Factors Affecting Strength and Stiffness of Dry Sand-
Rubber Tire Shred Mixtures
B. R. Madhusudhan .A. Boominathan .Subhadeep Banerjee
Received: 25 October 2017 / Accepted: 18 December 2018 / Published online: 19 January 2019
ÓSpringer Nature Switzerland AG 2019
Abstract This paper deals with the characterization
of dry sand-rubber tire shred mixtures to find shear
strength and dynamic properties. A series of ordinary
triaxial shear tests, direct shear tests and dynamic
triaxial tests were performed on dense dry sand-rubber
tire shred mixtures for various rubber replacement
levels such as 0, 10, 30, 50 and 100% by weight. The
effects of rubber content, confining pressures and rates
of shearing on the angle of internal friction of the
mixtures were investigated. Also, the influence of
rubber content and the rate of horizontal displacement
on the volumetric strain is presented. In addition, this
paper proposes an appropriate method to find the angle
of repose of dry sand-rubber tire shred mixtures. The
angle of repose of the mixtures is compared with the
angles of internal friction obtained from triaxial shear
and direct shear tests. Finally, the effects of saturation,
rubber content, axial strain, frequency and number of
cycles of loading on the strain-dependent stiffness and
damping properties of these mixtures were studied.
Keywords Dry sand-rubber tire shred mixtures
Friction angle Angle of repose Dynamic triaxial
Shear modulus Damping
1 Introduction
It is a known fact that the stockpiling of scrap rubber
tires is an environmental issue. The rubber is a non-
biodegradable material and its accumulation causes
serious environmental imbalances. It is known as
‘black pollutant’ (Xiong and Li 2013). Hence, the
utilization of scrap rubber tires is of paramount
importance. In the past, the properties of scrap rubber
tires have been investigated for various applications
such as in highway embankments, highway construc-
tion, landfills as leachate drainage materials, light-
weight backfills for walls and bridge abutments, slope
stabilization (Ahmed and Lovell 1993; Edil and
Bosscher 1994; Poh and Broms 1995; Foose et al.
1996; Bosscher et al. 1997; Tweedie et al. 1998; Rowe
and McIsaac 2005). The past researches showed that
the sand and rubber tire shreds mixed in a controlled
proportion could also be one of the potential materials
for seismic base isolation system of buildings (Anas-
tasiadis et al. 2012a; Tsang et al. 2012; Madhusudhan
et al. 2017). However, most of such studies considered
the saturated sand-rubber tire mixtures for their
investigations (Anastasiadis et al. 2012a; Senetakis
et al. 2012a; Nakhaei et al. 2012; Ehsani et al. 2015;
B. R. Madhusudhan A. Boominathan (&)S. Banerjee
Department of Civil Engineering, Indian Institute of
Technology Madras, Chennai 600036, India
B. R. Madhusudhan
S. Banerjee
Geotech Geol Eng (2019) 37:2763–2780,-volV)(0123456789().,-volV)
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Additionally, promising directions include their use in mitigating the liquefaction potential of saturated sands and improving the dynamic response of geosystems (Shrestha et al. 2016;Enquan and Qiong 2019), enhancing slope stabilization (Uchimura et al. 2007;Hazarika et al. 2008Hazarika et al. , 2020Belabdelouhab and Kebaïli 2015;Mirnaghizadeh et al. 2020), and enhancing the behavior of soft soils or geotechnical structures (Almeida et al. 2018;Chegenizadeh et al. 2018). Many previous studies have investigated the mechanical behavior of these granular composites using static (Edil and Bosscher 1994;Zornberg et al. 2004;Ghazavi and Shakhi 2005;Fu et al. 2014;Mashiri et al. 2015) and dynamic (Feng and Sutter 2000;Anastasiadis et al. 2012;Senetakis et al. 2012;Bahadori and Manafi 2015;Madhusudhan et al. 2019) element testing to explore the influence of rubber inclusion and content. Particular interest by the geotechnical engineering community also has focused on the study of composite sand-rubber against geotextile interfaces (Bernal et al. 1997;Tatlisoz et al. 1998). ...
... Such behavior confirms the significant contribution of the normal stress to the variations of the secant shear stiffness, and that if can be more noticeable in samples with lower rubber contents. This behavior was also reported by Thay et al. (2013), Vieira et al. (2013), and Madhusudhan et al. (2017Madhusudhan et al. ( , 2019 using cyclic triaxial or simple shear tests of granular materials. ...
... The decrease of the macroscopic stiffness in the present samples can be explained partly from the micromechanical observations of interfaces between rubber and geomaterials (of the grain-grain or flat-grain configurations) as reported in recent grain-scale studies which showed that the contact stiffness decreases due to the highly deformable nature of rubber particles and the subsequently reduced contact stiffness Tian and Senetakis 2022). In terms of macroscopic observation, this behavior conforms with the recent findings by Madhusudhan et al. (2019) for unreinforced sandrubber chips mixtures, in which increasing the rubber chips content from 0% to 50% caused a 37% reduction in the shear modulus of the composite soil. The contribution of granulated rubber inclusion to the reduction of shear stiffness was more pronounced at lower semiamplitudes of vibration. ...
A set of 48 cyclic and 12 monotonic large-scale direct shear tests was performed to assess the interface properties of sand–rubber composite along a nonwoven geotextile layer. Rubber content, semiamplitude of the shear displacement, and applied normal stress all were varied to determine the cyclic, postcyclic, and monotonic interface response of the composite system under shear loading. The test results show that adding 40% granulated rubber to pure sand caused approximately 50% reduction in the maximum mobilized interface shear stress as the loading cycles progressed. The addition of granulated rubber to the sand decreased both the damping and the shear stiffness of the interface for all values of displacement amplitude and normal stress; in particular, for the energy dissipation, the observations were associated with the higher linearity of the stress–strain relationship when adding rubber, thereby reversing the typical trend of higher damping at smaller strains or displacements. In addition, an increase in the displacement amplitude value yielded a reduction in the secant shear stiffness, but contrarily increased the damping ratio of the geotextile–composite soil interface. An increasing trend of the hardening factor was observed through the initial cycles of loading for the samples containing 40% granulated rubber, which was ascribed to the increased densification capability of the sand–rubber mixture with the progression of the loading cycles; however, this response was not captured for the pure sand–geotextile interface.
... Lee et al. [28,29] observed that the internal friction angle decreased with the rate of rubber particles in mixture and the inclusion of rubber particles provides a more ductile stress-strain response. Madhusudhan et al. [30] compared the variation of angle of repose and internal friction angle with the increase of rubber content, revealing that the internal friction angle decreased, while angle of repose increased up to a particular rate of rubber inclusion. Li et al. [11] reported that the rubber particles filled the pores between the sand particles under the effect of confinement so that peak friction angle of sand tended to decrease, and the rate of reduction was more significant for dilative sands. ...
... The rubber particles contribute to the contraction response in the mixtures due to their high deformability feature. Hence, the interlocking mechanism that is the substantial source of the dilatancy vanishes as the contacts involve a softer element [30]. ...
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In this study, the effect of particle size and shape parameters on shear strength of sand–rubber mixture was investigated using repose angle, as an analogy to the constant volume response, maximum dilatancy, and peak internal friction angles for various mixture conditions. For this purpose, four different granulated rubber and sand sizes were used to include the particle size effect. The size ratio of rubber and sand was maintained as unity in the mixtures. The influence of particle shape was reflected using three different shape classes for sand and two different particle forms for rubber granules. The shape properties of particles were quantified using overall regularity parameter with image processing. The percentage of rubber in the mixtures was varied at five different rates by weight of total sample. As a result, it was observed that the soft-rubber inclusion affected the shear strength parameters distinctively. The geometrical properties of sand and rubber particles have leading roles in the evolution of shear strength. Graphical Abstract
... Above-mentioned studies employed dynamic loading tests in accordance with the interest of the strain level (e.g. high-low amplitude torsional resonant column, cyclic triaxial, dynamic hollow cylinder test).In each of the performed studies, it is reported that the increase of rubber inclusions to the sand changes the behavior of the mixture from soil-like to rubber-like behavior.In many of the studies, rubber material has been utilized in shredded, granulated, and chips forms in mixtures (Edincliler et al. 2004;Sadeghi and Beigi 2014;Sanchez et al. 2018;Madhusudhan et al. 2019c;Enquan and Qiong 2019). Using the available literature data and results, the effects of different processed rubber/waste tires addition on the shear modulus and damping rate of the mixtures that can support the purpose of this study are summarized in Table 1.The effects of the same processed rubber in different sizes are also evaluated. ...
... They mentioned that the mixture with 10% rubber content by weight may be used for seismic base isolation of low-rise buildings. Madhusudhan et al. (2019c) reported that the damping ratio reached up to 40% with 10% inclusion of rubber shred by weight showed satisfactory static and dynamic properties and thus may be used for seismic base isolation of low-rise buildings. Fakharian and Ahmad (2021) mentioned that granulated rubber-sand mixtures can be used as a low-cost isolation material against seismic excitations exhibiting the required damping ratio of about 15%. ...
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Processed waste tires can be used as additives for geotechnical applications in earthquake-prone areas. The increasing use of waste tires additives requires a better understanding of their dynamic behaviors. Processed waste tires as granular and fiber-shaped rubber particles under the same experimental conditions were not studied before. The main purpose of this study is to carry out these experiments to determine the effects of two different processing techniques on the shear modulus and damping ratios of the mixtures. It is also the first time that the effects of fiber-shaped rubber particle inclusions are determined in detail.In addition, the results of similar tests using different processed waste tires were evaluated. The effects of the processed waste tires are given by evaluating the literature and this study together. It has been found that depending on the size, aspect ratio and content of the rubber material, the type of processing can significantly affect the dynamic properties of the mixture.The tested materials may be suitable as base isolation material. Of all the studies evaluated, the highest damping ratio was obtained with granulated rubber inclusions.
... Other previous studies carried out in several laboratories have shown that increasing the rubber content in sand decreases the shear strength of the mixture [7][8][9][10][11][12][13][14][15]. Several studies [7][8][9][10] showed that the shear strength and the friction angle increase with the rubber content of tires (thinner size) up to 20%, but beyond this value the last two decreases. ...
... Other previous studies carried out in several laboratories have shown that increasing the rubber content in sand decreases the shear strength of the mixture [7][8][9][10][11][12][13][14][15]. Several studies [7][8][9][10] showed that the shear strength and the friction angle increase with the rubber content of tires (thinner size) up to 20%, but beyond this value the last two decreases. Ghazavi et al. [11] showed that the shear strength increased up to an optimum of 30% by volume of granulated rubber. ...
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The main objective of this study is to compare the mechanical behavior of two sands (Hostun or Dune sands) mixed with crushed rubber obtained from used tires. However, it is essential to ensure that his geotechnical application do not result in long-term negative impacts on the environment. The chemical properties of these two sands are given by energy dispersive analysis X-ray fluorescence spectrometry. The mineral composition of these two sands is performed by X-ray diffractometry. The morphological characteristics of the sand grains are given by the analysis of the images of the two sands given by the scanning electron microscope. This study is based on 120 direct shear tests performed on sand-rubber aggregate mixtures. The results show that the rubber content of the aggregates has a significant effect on the shear strength of sand-rubber mixtures in both cases of sand. In fact, the shear strength of the sand-rubber mixture increases with increasing crushed rubber up to 20% for different normal stresses. The analysis of the test results also shows the effect of the angular shape of the sand grains on the interparticle friction. The contribution of the structure effect in the mobilized friction is analyzed by comparing the shear test results of Hostun and dune sand mixtures.
... Fu et al. [10] also highlighted that the size and aspect ratio of rubber particles has a significant influence in the mixture shear behaviour. While shreds and larger chips typically increase the peak strengths (e.g., [11,12]), smaller chips, crumbs or granules often either have no effect on the strength or a negative one (e.g., [13][14][15]). ...
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Slags and rubber from end-of-life tires represent a liability to the steel and tire industry, causing economic and environmental problems that are difficult to manage. Transport infrastructures can use these industrial by-products instead of extracting natural raw materials, but the adequate mechanical performance of the materials needs to be assured. This paper addresses the mechanical behaviour of slag–rubber mixtures in the laboratory with CBR, monotonic and cyclic triaxial tests. In addition, light falling weight deflectometer tests were also performed in a physical model. The results were analysed to meet technical specifications from Brazil, Portugal and Australia using railway sub-ballast layers, capping layers or road pavement layers as the base and sub-base to identify the applicability range of slag–rubber mixtures for transport infrastructures. Concerning the analysed parameters, it was demonstrated that slag–rubber mixtures can show resilient behaviour and strength adequate for the support layers of transport infrastructures provided that the rubber content is below 5% in weight and that the slag is milled to comply with the grain size distribution ranges available in the technical specifications of the cited countries.
... Much research has been conducted on the behavior of sand under cyclic loading using cyclic triaxial tests, with the focus being on the effects of confining pressure, loading amplitude and frequency, over-consolidation ratio, fine particle content, and relative density, etc. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Sharma and Maheshwari [21] conducted cyclic triaxial tests on sands with different degrees of saturation and found that the damping ratio of saturated sand is greater than that of dry sand and partially saturated sand. ...
Full-text available
In view of the dynamic response of geogrid-reinforced gravel under high-speed train load, this paper explores the dynamic characteristics of geogrid-reinforced gravel under semi-sine wave cyclic loading. A number of large scale cyclic triaxial tests were performed on saturated gravelly soil reinforced with geogrid to study the influence of the number of reinforcement layers and loading frequencies on the dynamic responses of reinforced gravelly sand subgrade for high speed rail track. The variation of cumulative axial and volumetric strains, excess pore pressure and resilient modulus with number of loading cycles, loading frequency, and reinforcement arrangement are analyzed. The test results reveal that the cumulative axial strain decreases as the number of reinforcement layers increases, but increases with loading frequency. The resilience modulus increases with the number of reinforcement layers, but decreases as the loading frequency increases. The addition of geogrid can reduce the excess pore water pressure of the sample, but it can slightly enhance the rubber mold embedding effect of the sand sample. As the loading frequency increases, the rubber mold embedding effect gradually weakens.
... The deformability of recycled tire particles in the mixture can allow the material to deform in macroscale until the point where enough interparticle contacts are created to carry the load (Kim and Santamarina 2008;Mohammadinia et al. 2018). There are a considerable number of studies on the shear strength, deformability, density, and dynamic properties of unbound sand-rubber mixture (with a variety of size ratios and fractions) in the literature (Youwai and Bergado 2003;Zornberg et al. 2004;Lee et al. 2007; Kim and Santamarina 2008;Lee et al. 2010a, b;Zhang et al. 2016Zhang et al. , 2018Anvari et al. 2017;Mohammadinia et al. 2018;Liu et al. 2018;Benessalah et al. 2019;Pasha et al. 2019;Qi et al. 2019;Madhusudhan et al. 2019Madhusudhan et al. , 2020Senthen Amuthan et al. 2020;Rios et al. 2021). ...
Mixtures of recycled tires and granular material have been used for a variety of applications in geotechnical engineering over the years. The characteristics and mechanical properties of sand–rubber mixtures as unbound soft–rigid mixtures have been extensively studied over the years. Research on bound soft–rigid mixtures, however, has been mainly focused on using a brittle binding agent, for example, Portland cement. A very limited number of studies over the last years have examined the behavior of soft–rigid mixtures bound with a nonbrittle binder. This study aims to provide a better understanding of the deformation mechanism of the soft–rigid mixtures bound with a polyurethane binder. Sixteen one-dimensional compression tests were conducted on bound and unbound samples to study the impact of the binding agent on the behavior of the soft–rigid mixture. In addition, computed tomography scan images of samples were used to visualize the deformation mechanism. A multiphased behavior, as opposed to single-phased behavior for unbound mixtures, was observed and each phase was explained in detail. The observed multiphased behavior is divided into up to four phases, that is, initial compression, normal compression, bond degradation, and secondary compression, with boundaries defined based on constrained modulus curve.
The use of end-of-life tire (ELT) rubber in rubberized cementitious materials (RCM) as a partial alternative aggregate has attracted the attention from researchers and industries in the recent decades. While the ELT rubber can be advantageous, such as by increasing fracture toughness, ductility, permeability, and thermal insulation of the concrete, it can negatively impact the other engineering properties, such as elastic modulus, mechanical strength, stiffness, and shrinkage. This reduction in performance may be attributed to the poor interfacial contact and bonding between the rubber particles and cement paste. This manuscript presents a comprehensive literature review on how ELT rubber has been physically and/or chemically treated to improve the properties of the rubberized cementitious composite. Specifically, this work (i) summarizes various treatment methods that have been employed to treat the ELT rubber surface before use in RCM; (ii) presents the hypothesized mechanism(s) behind each treatment method as well as the changes in the ELT rubber’s microstructure (if applicable); and (iii) provides discussions and comparisons between the developed pretreatment methods for ELT rubber. Two metrics – strength recovery index (SRI) and strength gain (SG) – are introduced to assist with comparisons. Also, recommendations are provided to assess the most effective pretreatment methods for ELT rubber in RCM in terms of engineering properties.
Among the numerous studies into the dynamic loading behaviour of rubber crumbs-soil/waste mixtures, the main focus is on how the content of rubber crumbs (R b %) affects the damping ratio, shear modulus and total deformation. However, the research into the influence of R b % on the permanent strain rate ([Formula: see text]) and the deformation mechanism under repeated loading is very limited. In this current study, the cyclic deformation response for the waste mixtures of steel furnace slag (SFS), coal wash (CW) and rubber crumbs (RC) are analysed and the test results reveal that R b % has a significant influence on the initial [Formula: see text] and the slope of the permanent axial strain rate line (PASRL), while cyclic deviator stress (q cyc ,max ) mainly affects the initial [Formula: see text]. The influence of R b % and q cyc ,max on [Formula: see text] of the waste mixture is incorporated in an empirical model, which enables to predict the permanent deformation mechanism of SFS+CW+RC mixtures with broader ranging amounts of RC and higher cyclic deviator stresses.
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Dynamic shear modulus plays an important role in seismic assessment of geotechnical systems. Changes in degree of water saturation influence dynamic soil properties due to the presence of matric suction. This paper describes the modification of a suction-controlled cyclic triaxial apparatus to investigate strain-dependent shear modulus of unsaturated soils. Several strain-controlled and stress-controlled cyclic triaxial tests were performed on a clean sand with various degrees of saturation. Suction in unsaturated sands increased the shear modulus in comparison with the ones in dry and saturated conditions for different shear strain levels, with a peak modulus in higher suction levels. Also, shear modulus decreased by increasing the shear strain for specimens with similar matric suction. The normalized shear moduli of the unsaturated sand specimens followed a similar trend to the ones predicted by the available empirical shear modulus reduction functions, but showing lower normalized shear modulus values. Modulus reduction ratios of unsaturated sands shifted up as a result of higher effective stress and suction-induced stiffness. These trends were consistent for both strain- and stress-controlled tests.
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Recycled waste tires when mixed with soil can play an important role as lightweight materials in retaining walls and embankments, machine foundations and railroad track beds in seismic zones. Having high damping characteristic, rubbers can be used as either soil alternative or mixed with soil to reduce vibration when seismic loads are of great concern. Therefore, the objective of this work was to evaluate the dynamic properties of such mixtures prior to practical applications. To this reason, torsional resonant column and dynamic triaxial experiments were carried out and the effect of the important parameters like rubber content and ratio of mean grain size of rubber solids versus soil solids (D 50,r/D 50,s) on dynamic response of mixtures in a range of low to high shearing strain amplitude from about 4×10-4% to 2.7% were investigated. Considering engineering applications, specimens were prepared almost at the maximum dry density and optimum moisture content to model a mixture layer above the ground water table and in low precipitation region. The results show that tire inclusion significantly reduces the shear modulus and increases the damping ratio of the mixtures. Also decrease in D 50,r/D 50,s causes the mixture to exhibit more rubber-like behavior. Finally, normalized shear modulus versus shearing strain amplitude curve was proposed for engineering practice.
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The primary objective of the study is to estimate the energy absorption (EA) capacity, brittleness index (ductility) and stiffness characteristics of Sand-Tire Crumb Mixtures (STCM) using direct shear test and Unconsolidated Undrained (UU) triaxial test for the effective reuse of waste tire crumbs as isolation materials. The properties considered include, strength and deformation characteristics of a STCM. A relatively uniform sand and readily available tire crumb grouped into four size has been selected to generate STCM. Experimental studies have been carried out on STCM with constant density of 1.54 g/cc. Stress-strain curve obtained from UU test has been used to estimate EA. The experimental results show that peak strength, EA and stiffness increases with increasing percentage of tire crumbs up to 25% and starts decreasing thereafter. Among the tested tire crumb sizes, crumb size IV provide the maximum EA without compromising on strength compared to other tire crumb sizes.
The sand-rubber tire shred mixtures have recently gained the attention of researchers for its potential application as seismic isolation materials. The determination of strain-dependent dynamic properties is crucial for the seismic performance of sand-rubber tire shred mixtures. The cyclic triaxial tests are widely used to find out the dynamic properties of soils due to simplicity. However, it does not simulate the actual stress conditions in the field during an earthquake. The dynamic simple shear tests best simulate the field seismic stress conditions. Therefore, in the present study, the results of dynamic simple shear tests carried out on sand-rubber tire shred mixtures are compared with the results of cyclic triaxial tests. Strain-controlled dynamic simple shear tests were carried out on saturated and isotropically consolidated sand-rubber tire shred mixtures with various gravimetric proportions of sand content (50 to 90%). The samples were subjected to cyclic loading with a frequency of 1.0 Hz. It was found that the shear modulus and damping ratio of sand-rubber tire shred mixtures were highly dependent on shear strain and sand content. The effect of number of loading cycles on the dynamic properties was also investigated. It was also found that the cyclic triaxial tests grossly overestimate the shear moduli but the damping ratios were comparable to those obtained from dynamic simple shear testing.
This paper presents the results of experimental investigations on sand–rubber tire shred mixtures. The sand and rubber tire shreds considered were of uniform fine size (<2 mm). Static and dynamic characterization was carried out for pure sand, pure rubber, and sand–rubber tire shred mixtures with rubber content varying 10, 30, and 50% by weight. First, strain-controlled consolidated undrained triaxial tests were carried out to determine static shear strength. Strain-controlled cyclic triaxial tests were then conducted to evaluate shear moduli and damping ratios in the medium to large strain range. Undrained moduli obtained from both experiments were compared. It was found that the mixture with 10% rubber content had the satisfactory static and dynamic properties required for seismic isolation of low-rise buildings.
Tire particles in the form of shreds, chips, or crumbs, are normally mixed with sand to make suitable alternative backfill or embankment materials. This mixture of soft (tire) and rigid (sand) particles in their optimum ratio has been shown to provide reasonable engineering performance in terms of strength, permeability, durability, and compressibility. In this study, mixtures of fine recycled glass (FRG) and tire crumbs (TC) were evaluated through isotropic compression tests, as well as consolidated drained triaxial tests under five confinement levels. Four proportions of mixtures with gravimetric TC contents of 10-40% were evaluated in terms of shear and compression response. Results show that, increasing the TC content decreases the shear strength parameters and Young's modulus, and increases the compressibility of the mixture. Gravimetric TC content corresponding to the transition mixture in high and low confinements were between 10 and 20%, and 20 to 30%, respectively. In mixtures with a TC content less or greater than that of a transition mixture, a FRG or TC skeleton was found to govern the behavior of the mixture. The outcomes of this research study were compared with results of investigations carried out on sand-rubber mixtures, and possible applications of this fully recycled product are discussed.
Resonant column tests, corresponding to a given input voltage of the drive mechanism, were conducted in torsional mode to examine the effect of vibration cycles on shear modulus (G) and damping (D) of dry sand with shear strain amplitude in a range of 0.0005-0.05%. Two different relative densities, approximately 61 and 85%, and effective confining pressures, 300 and 500 kPa, were used. The specimens were subjected to a number of vibration cycles ranging from 1,000 to 50,000. The shear modulus and damping ratio, before and after the application of vibration cycles, were determined for several input voltages. An induction of the vibration cycles leads to a continuous increase in shear strain, which causes (1) a decrease in the shear modulus and (2) an increase in the damping ratio. This effect becomes especially more prominent for lower values of relative densities and confining pressures. The modulus reduction and damping curves remained the same after applying vibration cycles.
Processed tire wastes mixed with soils are applicable as lightweight fillers for slopes, subbases of pavements and retaining walls that may be subjected to seismic loads, e.g., earthquake or traffic loads. The dynamic response of granulated rubber-soil mixtures, such as the dynamic shear modulus, damping factors and liquefaction resistance, is essential in the design of such a system. This report presents the results of the dynamic behavior of granulated rubber-sand mixtures using resonant column tests and cyclic triaxial tests to assess the potential use of recycled rubber crumb in improving the performance of granular materials by mixing with different tire crumb sizes and fractions. Two contact types are identified that could explain the evolutionary behavior of the shear modulus and the damping ratio. The results of the rubber-sand mixtures are compared with the results from the literature. The mix ratio is shown to significantly influence the dynamic shear modulus and the liquefaction susceptibility. The results serve as a supplement to enrich the database of the dynamic behavior of soil-rubber mixtures as lightweight filler materials in dry and saturated conditions.
Sand–tyre chip (STCh) mixtures can be used in many geotechnical applications as alternative backfill material. The reuse of scrap tyres in STCh mixtures can effectively address growing environmental concerns and, at the same time, provide solutions to geotechnical problems associated with low soil shear strength and high dilatancy. In this paper, the shear strength and dilatancy behaviour of STCh mixtures have been investigated. A series of monotonic triaxial tests has been carried out on sand mixed with various proportions of tyre chips. It has been found that tyre chips significantly influence the shear strength and the dilatancy behaviour of STCh mixtures. The effects of confinement and relative density on the shear strength, dilatancy and initial tangent modulus of the STCh mixtures have also been investigated. Moreover, a dilatancy model for STCh mixtures has been proposed and validated with the experimental results.