Rubber Particle Size Research Articles

A comprehensive review on polystyrene/waste rubber blends: Effective parameters on mechanical properties

AbstractPolystyrene (PS), as a commercial thermoplastic polymer, suffers from brittleness at low temperatures. Blending with elastomers can resolve this defect. In this regard, waste rubbers from tires, shoes, and other sources are promising candidates for some applications. This approach of waste rubber recycling is an environmental‐friendly and economical method to produce value‐added products. This work aims to comprehensively review all reported cases regarding PS (or high‐impact polystyrene, HIPS, and expanded polystyrene, EPS)/waste rubber blends. The influences of different parameters on the mechanical properties were carefully summarized, including mixing conditions (temperature, mixing time, rotor speed, and mixing sequence), rubber content, rubber particle size, compatibilizer addition, rubber devulcanization, and surface treatment of rubber. Some parameters had a negligible effect on the mechanical properties, such as the rotor speed in the mixing process, while significant influences were observed for some parameters, such as rubber content. The effect of some parameters was remarkable only at low or high rubber loading, such as particle size and solvent‐inducing surface treatment of rubber, respectively. Finally, the effects of aforementioned parameters on tensile and impact strengths were compared and recommendations for future research in this field were suggested.Highlights All reported research regarding PS/waste rubber blends was comprehensively reviewed. All different factors influencing mechanical properties were carefully summarized. The effects of different factors on tensile and impact strengths were compared.

Extractable latex yield from Taraxacum kok-saghyz roots is enhanced by increasing rubber particle buoyancy

Taraxacum kok-saghyz (TK) is a leading alternative rubber-producing plant that produces natural rubber (NR) latex in laticifers within its roots. Unlike the tropical rubber tree, Hevea brasiliensis, TK can be grown in temperate regions, such as the northern United States, as the basis of a domestic rubber production industry. To support such an industry, efficient, scalable rubber extraction techniques are needed. In this study, aqueous extraction was used to recover TK natural rubber latex (TNRL) from four harvests of greenhouse-produced TK roots with a new technique that improves rubber particle buoyancy in root homogenate by chelation. The new method includes harvest, cleaning, and homogenization of freshly harvested roots, followed by centrifugation, vacuum collection of latex, and purification. Treatment of homogenate with ethylenediaminetetraacetic acid (EDTA), a divalent cation chelator, allowed more than twice as much latex to be extracted from fresh homogenate. EDTA-treated rubber particles contained lower concentrations of divalent cations than untreated ones in fresh homogenate and homogenate stored for two weeks. Long term (three months) storage of root homogenate similarly yielded more latex than fresh homogenate and had low divalent cation rubber particle concentrations, indicating that heavy cations had slowly leached from the particles into the aqueous medium during storage. Rubber particle size was larger in this treatment suggestive of rubber particle agglomeration but this was prevented and reversed by EDTA. Removal of divalent cations via chelation increased particle packing density of particles in concentrated latex and appeared to increase the gel content of dried latex samples. Molecular characterization of dried samples of purified TNRL established that the rubber was of the high molecular weight needed for product manufacturing.

Comprehensive Study on Rubber Particle Size and Replacement Ratio on Fresh and Hardened Properties of Rubberized Concrete: A Review

The black pollution caused by the accumulation of Waste Tire Rubber (WTR) has engendered significant environmental and social consequences throughout the world by emphasizing the requirement of introducing a new approach to recycling WTR effectively. The recent research findings towards the utilization of End-of-Life Tires (ELT) to replace the Natural Aggregate (NA) in concrete have facilitated a promising way to handle the WTR while reducing the consumption of natural raw materials in the construction industry. However, the weak Interfacial Transition Zone (ITZ) between rubber aggregate and cement paste reduces the properties of Rubberized Concrete (RuC) and hinders its commercial usage. Among the many factors, the rubber particle size, shape, and Replacement Ratio (RR) significantly influence the performance of RuC. This paper reviews previous research findings relevant to the effect of the rubber particle size, shape, and percentage replaced in the concrete mix to pinpoint the further research gaps to be investigated. Overall, the previous findings indicate that the tire aggregate inclusion at a low level of replacement in the form of crumb rubber resulted in improved ductility and toughness with marginal impacts on workability, strength, and other mechanical properties of concrete compared to the control mix without WTR.

Macro and micro analyses of static and dynamic shear characteristics of geogrid and rubber–sand mixture interface

A rubber–sand mixture (RSM) can be used as a novel type of geotechnical material in reinforced roadbeds and other projects owing to its being elastic and environment friendly. To explore the static and dynamic shear characteristics of the geogrid and RSM interface, monotonic direct shear (MDS), cyclic direct shear (CDS), and post-cyclic monotonic direct shear (PCDS) experiments were performed in this study. The effects of rubber content (χ) and particle size ratio (r) on the interface shear characteristics were studied. A dynamic model of the rubber–sand mixture was established using PFC3D, and mesoscopic analysis of the cyclic shear process was conducted. The results of the CDS experiments indicated that the peak shear stress with χ = 10 % was the largest. The peak strength and residual strength of PCDS were larger than those of MDS under the same χ and r. After cyclic shearing, the interface apparent cohesion of various rubber contents and particle size ratios increased by 78 % ∼ 172 %. During cyclic shearing, the porosity and particle energy in the shear box changed periodically, and the porosity near the interface was slightly higher than that in the other areas. The kinetic energy of the particles was closely related to the shear displacement.

Improving thermal characteristics and energy absorption of concrete by recycled rubber and silica fume

The two conventional disposal methods as landfilling and incineration of waste rubber raise environmental concerns. It is while burying rubber in concrete enhances flexibility and thermal properties due to its inherent ductility and insulation properties. In this study, a comprehensive approach has been adopted to investigate the effects of the amount and size of rubber particles combined with silica fume on the thermal characteristics, energy absorption, and mechanical properties of concrete, including its workability, specific weight, thermal conductivity, thermal performance, compressive strength, flexural strength, and flexural toughness. In addition, statistical analyses were conducted to evaluate the experimental results. It was observed that in concrete containing 50% fine or 50% coarse rubber aggregates combined with 15% silica fume, the thermal conductivity decreases by 45% and 43%, respectively. The energy absorption of concrete samples with 100% fine or 100% coarse rubber particles increased by 2.8 and 4.5 times, respectively, compared to those with 20% rubber. Appropriate equations were developed to estimate the compressive and flexural strengths of concrete with rubber particles while statistical analyses exhibited error levels of 11% and 15%, respectively, for such equations. The compressive and flexural strengths decreased by an average of 68% and 62%, respectively, in samples containing 100% crumb rubber. Likewise, these factors experienced an average reduction of 73% and 71%, respectively, in specimens with 100% rubber powder compared to those with 20% rubber.

Experimental study on shear mechanical properties of improved loess based on rubber particle incorporation and EICP technology

Loess is often not suitable for direct use as a roadbed or building foundation due to its collapsibility, and it needs to be improved by adding curing agents. Taking the loess in Xi’an area as the research object, the reinforcement of loess was carried out using waste tire rubber particles and Enzyme Induced Carbonate Precipitation (EICP) technology. The change of shear strength and shear strength index of improved soil with rubber content and rubber particle size under different strengthening conditions was analyzed, and the strengthening mechanism was also expounded. The results show that rubber powder can improve the shear strength of loess to a certain extent, and the combination of EICP technology can increase the strength of improved loess by nearly 50%. In addition, rubber particles have a certain inhibitory effect on EICP, and the shear strength growth rate decreases with the increase of rubber content. When the rubber particle size is 1–2 mm, the shear strength growth rate is the highest. It is suggested that when adding rubber particles or adding rubber particles combined with EICP technology is used to improve loess, the rubber particle size should be selected as 1–2 mm, and the content is about 10%. The test results can provide a scientific basis for the reduction of geologic disasters in loess areas, and at the same time can provide a non-polluting way for the disposal of waste tires.

Eco-friendly concrete produced with recycled materials

Using recycling materials to produce concrete become a major subject for research in the last decades. The work aims to examine the effects of the partial replacement of fine aggregate by recycled rubber. In addition to studying the influence of two different fiber types on mechanical properties of concrete with rubber replacement. Three types of rubbers that differ in particle size are used to find the effect of rubber particle size on compressive strength, splitting tensile strength, and flexure strength of the concrete mix. Two waste fiber types are used which are Rope Waste Fiber (RWF) and Steel Waste Fiber (SWF). The findings showed that minimizing the rubber particle size improved the mechanical properties. Also, using two types of waste fiber (rope and steel) together led to improve compressive strength.

The mechanics and durability of rubber fiber hydraulic concrete on laboratory

AbstractThis study delves into the mechanical and durability properties of rubber fiber hydraulic concrete (RFHC) using an orthogonal testing method. The optimal mix proportion for RFHC is determined through orthogonal range and variance analysis results. The influence of polypropylene fiber content, rubber particle content, and rubber particle size on the compressive strength, flexural strength, split tensile strength, brittleness, and crack resistance of rubber fiber concrete is thoroughly examined. Durability tests are conducted based on the optimal mix ratio, and a comparative analysis of the durability between RFHC and conventional concrete is carried out. The findings indicate that the mechanical properties of the concrete exhibit a significant decline with increasing rubber content and decreasing rubber particle size. The variation in rubber content notably affects the mechanical properties of hydraulic concrete. The frost resistance and impermeability of RFHC are considerably higher than those of conventional concrete, while the erosion resistance of RFHC surpasses that of the conventional benchmark concrete. This research offers valuable benchmarks for the theoretical design and practical engineering application of RFHC, contributing to the advancement of sustainable construction materials.

Experimental and theoretical study on elliptical rubber concrete filled double-skin GFRP short tubes under axial compression

This study proposed a double-skin section consisted of an elliptical glass fiber reinforced polymer (GFRP) outer tube, a circular steel inner tube and rubber concrete filled between them, which had the features of aesthetic appeal, structural efficiency and waste recycle. Axial compressive test was conducted on the elliptical rubber concrete filled double-skin GFRP tubular (CFDST) short columns with various void ratios and rubber contents. Load-axial strain-hoop strain data was obtained from the experiments and the contribution of each component (i.e., concrete, GFRP tube, steel tube) to resist the applied load was clarified. Experimental results indicated that the void ratio and rubber content had the most significant effects on the dilation property (i.e., hoop and axial strains) and confinement effect of the rubber concrete. Nevertheless, effects of steel tube thickness and rubber particle size were insignificant. Based on the experimental results and confining concrete theories, a theoretical model, with proper considerations on the effects of void ratio, rubber content and aspect ratio, was proposed to estimate the ultimate load-carrying capacity and ultimate strain of the stub columns under axial compression. Finally, reasonability and accuracy of the proposed model were verified by the experimental results.

Reduction in Soil Compaction by Utilization of Waste Tire Rubber

Hardpan is one of the major problems found in many parts of Thailand where monocropping and repeated plowing at the same depth are conducted. This work aimed to study the feasibility of using crumb rubber produced from waste tires to alleviate the soil compaction problem. Effects of particle size and loading of crumb rubber on the degree of soil compaction were investigated. The quality of water extracted from crumb rubber was also analyzed to determine the severity of environmental contamination. The scope of work was further extended into field tests. The results reveal that the addition of crumb rubber into sandy loam subsoil significantly reduced the bulk density of the compacted soil and permitted greater water permeation through the compacted soil layer. The effects were more pronounced with either increasing crumb rubber loading or reducing crumb rubber particle size. For the field test, the addition of small crumb rubber (S-crumb) at 30%wt. resulted in a significant reduction in penetration force in conjunction with a considerable increase in water permeability. The results clearly confirm the reduction in soil compaction by the addition of crumb rubber. From a quality analysis of the extracted water, most poisonous heavy metals were below the detection limits of the test equipment, except zinc.

Experimental Study on Unconfined Compressive Strength of Rubberized Cemented Soil

As an economical and environmentally friendly lightweight filler material, rubberized cemented soil has a broad application prospect in engineering. In order to analyze its engineering characteristics, the stress-strain curves were obtained by the unconfined compressive strength test under different compounding conditions, focusing on the changes in rubber particle size, rubber content, cement content, and curing age on the strength of rubberized cemented soil. Results indicate that: we can divide the stress-strain curve of rubberized cemented soil into four stages: compression dense stage, elastic deformation stage, yielding stage, and post-damage stage; the ductility and plasticity change regularly with cement content, rubber content, and rubber particle size; the strength of rubberized cemented soil increases with the increase of cement content and decreases with the increase of rubber content; In the content range of this test, the strength growth rate is the largest at the level of 5% – 10%, and the strength reduction rate is the smallest at 0% – 5% of rubber powder content; the unconfined compressive strength decreases and then increases as particle size grows, reaching its lowest value at 1 – 3 mm, which is considered to be the inferior particle size and the verification of the existence of the optimum particle size; the unconfined compressive strength of rubberized cemented soil has an excellent linear relation with the natural logarithm of the curing age, and its strength increases with the increase of lnT; a new comprehensive characterization parameter PCRT is proposed, which can effectively characterize the effects of rubber content, cement content and curing age on the compressive strength of rubberized cemented soil, and has a good power function relation.

Morphology and aggregation process of natural rubber particles

Natural rubber particles (NRPs) are the main place of natural rubber biosynthesis and storage which exist as the organelle in the latex tube cells of rubber trees. Here, we observed the aggregation process from the morphology of rubber particles and correlated the aggregate structure with the mechanical properties. The rubber particle sizes were first examined by optical microscopy, and the distribution showed a Gaussian curve with an average diameter of 1200 nm. Scanning electron microscopy (SEM) was then used to photograph the smaller particles, which supported a Gaussian distribution for NRPs smaller than 200 nm in diameter. They collectively indicated a bimodal distribution of NRP size, consistent with the results of the laser particle size analyzer. The percentage of the small rubber particles was measured to be 68.3 % and 31.7 % for the large rubber particles. The aggregation process of NRPs was observed as membrane fusion, superimposed aggregation, followed by the concavity of the inner core from the outside, and finally the formation of aggregated state rubber. Subsequently, the natural rubber latex films were obtained by spreading the latex at room temperature. The green strength was tested in its naturally dried stacked aggregated state, reaching a notable strength of 8 MPa. This was about 7 times higher than that of the ribbed smoked sheet (RSS). In contrast, when the naturally dried rubber film was processed by high-temperature molding and low-temperature setting, its green strength dropped to the level of the RSS. It thus supports that the processing methods, such as high temperature and shearing, could significantly impact the structure and performance of natural rubber (NR). Consequently, excellent performance of elastomeric materials might be reached under low-temperature drying and normal-temperature vulcanization processing methods.

Influences and mechanisms of pyrolytic conditions on recycling BTX products from passenger car waste tires

Pyrolysis is an effective method for waste tire disposal. However, it has rarely been used to recycle specific highly valuable components (such as benzene, toluene, and xylene (BTX)) from tire rubbers, owing to complicated pyrolytic reactions. This study investigated the pyrolysis process of passenger-car-waste-tires (PCWT) with the help of TG–DTG and Py–GC/MS. Based on response surface methodology (RSM), the effect of pyrolytic parameters on the yields of pyrolytic oil and BTX is evaluated. Furthermore, the BTX generation mechanisms are discussed from the perspective of aliphatic and aromatic hydrocarbon transformations. Additionally, pyrolytic conditions including temperature, rubber particle size, pressure, and gas flow rate were systemically investigated and the optimum pyrolytic condition for yield of BTX (26.5 g per 100 g tire rubber) was obtained [765 K, 0.7 mm, 0.52 MPa and 2.5 mL (g min)−1]. Therein, yield of benzene, toluene and xylene were 1.07, 5.03 and 20.40 g per 100 g tire rubber, respectively. During PCWT pyrolysis, BTX is primarily obtained via the Diels–Alder reactions of small-chain alkenes and transformations of limonene and aromatics. This study elucidates the BTX generation mechanisms during PCWT pyrolysis and clarifies the effects of varying pyrolytic conditions on BTX generation.

Deep learning models in Python for predicting hydrogen production: A comparative study

This study relates to predicting hydrogen production using deep learning models. The co-gasification of biomass and plastics dataset used gasification temperature, particle size of biomass rubber seed shell (RSS) and High-Density Polyethylene (HDPE), and the amount of plastic in the mixture as the independent variables, and the amount of hydrogen produced as the dependent variable. It was found that during the co-gasification particle size is a controlling factor for hydrogen production due to the influence on surface reactions, while temperature had no significant effect. The neural network models were developed using Keras and two different architectures were compared with and without L1 and L2 regularizers. The values for L1 and L2 are determined using the gridserach: for the 1 archtecture, the ideal L1 value = 0.010; and the ideal L2 value = 0.000001 and for the 2nd architecture, The ideal L1 value is 0.100; and the ideal L2 value is 0.000010 using the lowest mean squared error values for the test sets. The mean cross-validation scores indicated that the second architecture performed better. The mean cross_val_score using the negative mean square error, for the 1st architecture, with l2 regularizers (0.000001) is determined as −20.05 (13.10) nMSE for Kfold, 10; and for the 2nd architecture l2 regularizers (0.000010) as −8.22 (7.77) nMSE for Kfold, 10, indicate the 2nd architecture performs better. The best model parameters for both architectures were determined using Grid Search CV. The best model hyperparameters using Grid Search is batch_size, 3; epochs,100; optimizer, rmsprop for the first architechure with negative mean square error, −20.95; and for the 2nd architecture, batch_size, 5; epochs,100; optimizer, adam with negative mean square error, −7.38, indicating the 2nd architecture to be a better model. The Keras Wrapper improved the performance of the model for the first architecture, but not for the second architecture. The permutation feature importance for architecture 1 (in descending order) is: size of RSS, size of HDPE, per cent plastics in mixture and temperature. For architecture 2, in descending order: size of HDPE, size of RSS, per cent plastics in mixture and temperature. Overall, the study demonstrates the potential of deep learning models for predicting hydrogen production.

Mechanical Properties and Microstructure of Rubber Concrete under Coupling Action of Sulfate Attack and Dry–Wet Cycle

In order to study the mechanical properties of rubber concrete (RC) with different rubber particle sizes after dry–wet cycles in a sulfate environment, apparent morphology analysis, mass loss analysis, relative dynamic elastic modulus analysis, compressive strength loss analysis, internal microscopic characteristics and deterioration degree analysis of ordinary concrete (NC) and rubber concrete after dry–wet cycles were compared and analyzed. The results show that with the increase in the number of dry–wet cycles, the surface caves of rubber concrete increase, the internal microcracks develop and penetrate, and the macroscopic strength increases first and then decreases significantly. The high elasticity of rubber effectively improves the expansion force caused by sulfate attack and the dry–wet cycle. The deterioration degree of RC in each dry–wet cycle stage is obviously better than that of NC. When the rubber particle size is 0.85 mm, the performance of the sample is the best. After 120 days of dry–wet cycle, the compressive strength is reduced by 37.4%, and the compressive strength of concrete with a rubber particle size of 0.85 mm is reduced by 11.2%. After cyclic loading, the deterioration degree of concrete is 5.1% lower than that of ordinary concrete.

Experimental study on high temperatures performance of rubberized geopolymer mortar

Nowadays, fire accidents occur frequently, and both buildings and structures or traffic roads are threatened by fire to varying degrees, and the mortar structure is often in direct contact with fire. Therefore, it is necessary to study the performance of mortar under high temperature. Geopolymer is a new type of green environmental protection building material with good high temperature resistance. Waste rubber will soften and decompose under high temperature, and the holes formed can release the steam pressure inside the structure, which is helpful to ease the internal cracking of the structure. At present, it has been proved that waste rubber has a beneficial effect on the resistance of mortar to high temperature. The research of waste rubber in Portland cement mortar has made relevant achievements, but the research on the combination of geopolymer rubber is relatively small. Therefore, in view of this lack, this study supplements the material properties of geopolymer mortar under four rubber particle sizes (4, 1.7, 0.83, and 0.27 mm) and five temperatures (25, 200, 400, 600 and 800 °C), namely, surface observations, mass loss, compressive and flexural strengths, ultrasonic pulse velocity (UPV) and microstructure change. The results show that the addition of rubber particles will increase the mass loss of rubberized geopolymer mortar (RGM), but the advantage is that it can reduce the burst risk. The addition of fine particle rubber can improve the ability of RGM to resist cracking and deformation at higher temperatures. The results shows that the UPV can reflect the mass and intensity change of RGM laterally. The microscopic results shows that the main reason for the lower strength is the expansion of microcracks and pores in RGM matrix at high temperature.

Mechanical Properties and Microstructure of Rice Husk Ash-Rubber-Fiber Concrete under Hygrothermal Environment.

In order to study the mechanical properties of rice husk ash-rubber-fiber concrete (RRFC) under hygrothermal environment, the optimal group was selected by orthogonal test. The mass loss, relative dynamic elastic modulus analysis, strength analysis, degradation degree analysis after cyclic loading and internal microstructure analysis of the optimal group of RRFC samples after dry-wet cycles under different environments and temperatures were compared and analyzed. The results show that the large specific surface area of rice husk ash optimizes the particle size distribution of RRFC specimens, reacts to form C-S-H gel, enhances the compactness of concrete, and forms a dense structure as a whole. The presence of rubber particles and PVA fibers effectively improves the mechanical properties and fatigue resistance of RRFC. The comprehensive mechanical properties of RRFC with rubber particle size of 1-3 mm, PVA fiber content of 1.2 kg·m-3 and rice husk ash content of 15% are the best. The compressive strength of the specimens after dry-wet cycles in different environments generally increased first and then decreased, reaching a peak at the seventh dry-wet cycle, and the compressive strength of the specimens under chloride salt solution decreased more than that under clear water solution. Thes provided new concrete materials for the construction of highways and tunnels in coastal areas. Under the premise of ensuring the strength and durability of concrete, it is of great practical significance to explore new roads for energy conservation and emission reduction.

Reuse of waste rubber in pervious concrete: Experiment and DEM simulation

The reuse of waste rubber has a profound impact on environmental protection and resource recycling. To evaluate the feasibility of adding waste rubber into pervious concrete, the effects of rubber content and particle size on the mechanical properties of pervious concrete are investigated through experiments and discrete element method (DEM) simulation. The compressive failure mode of pervious concrete gradually transits from tensile failure to shear failure with the increase of rubber content, showing a decrease in compressive strength, and the larger the particle size is, the stronger the attenuation effect on the strength is. Rubber particles play a role in isolating coarse aggregates from the cement matrix and form a weak bond with the matrix, showing a weak bridging effect in stress transmission at the left and right ends of the crack, so that the splitting tensile strength of pervious concrete significantly decreases with the increase of rubber content, and the weakening effect of coarse rubber on the splitting tensile strength is stronger than that of fine rubber. Due to the low strength of rubber itself and weak bonding with cement matrix, pervious concrete with high rubber content breaks in advance at the bottom of the midspan, resulting in the decline of flexural capacity, and it decreases more obviously with the increase of rubber size. Although the direct tensile strength of pervious concrete gradually decreases with the increase of rubber content, the addition of rubber improves the plasticity of pervious concrete. Moreover, the plastic reinforcement effect of pervious concrete is the strongest when the rubber content reaches approximately 10%, and this toughening effect increases with the decrease of rubber size. On the basis of experimental research, a universal DEM model considering rubber content and particle size is established, which can well predict the mechanical performance of rubberized pervious concrete in terms of strength, failure mode, elastic modulus and ultimate strain.

A state-of-the-art review of rubber modified cement-based materials: Cement stabilized base

To further improve the durability of pavement structure and promote the research and application of rubber cement stabilized base, the research results of rubber modified cement-based materials and their cement stabilized base were systematically combed. The action principles of different rubber surface treatment technologies were revealed, and based on the principle of similar adhesion characteristics between rubber and cement-based materials, the treatment technology type and the optimal concentration of treatment agent suitable for rubber cement stabilized base were determined. The key sieve pass rate of mineral material gradation was recommended, and the best preparation process for rubber cement stabilized base was determined. The mechanical and fatigue properties of cement stabilized base with different rubber particle size and content were evaluated, the bonding and anti-cracking mechanism of the rubber cement stabilized base was explored. Results indicate that considering the treatment effect and cost, NaOH solution with concentration of 5% is recommended as rubber surface treatment agent. The discontinuous gradation with the aggregate nominal maximum particle size of 26.5 mm is the common gradation of rubber cement stabilized base. It is recommended that the passing rate of 4.75 mm, 2.36 mm and 0.075 mm sieve holes be controlled at 32–43%, 22–28% and 1.5–3.6% to ensure compactness. Compared with heavy compaction method, vibration compaction method not only has less aggregate damage, but also beneficial to reduce the dry shrinkage deformation of the rubber cement stabilized base. Compared with rubber powder (<0.6 mm), the 90 d compressive resilience modulus of the rubber particle（≥0.6 mm）cement stabilized base can be reduced by 25.16%, which has a more significant improvement in toughness. With the increase of rubber content, the mechanical properties of rubber cement stabilized base decreases gradually, the fatigue resistance and deformation ability are significantly enhanced, and it has good durability. This research results can provide scientific basis and theoretical support for rubber cement stabilization base engineering application and quality control.

Mesoscale Analysis of Rubber Particle Effect on Indirect Tensile and Flexural Tensile Strength of Crumb Rubber Mortar

This paper presents a mesoscale model to study the influence of rubber particles on the mechanical performance of crumb rubber mortar (CRM). The indirect tensile and flexural behaviors of CRM with different rubber replacement rates, shapes, and sizes were investigated. Rubber mortar is assumed to be a three-phase material composed of rubber aggregate, a mortar matrix, and an interface transition zone (ITZ). Numerical analysis showed that rubber content was the governing factor affecting the reduction rate of indirect tensile and flexural strength. The effect of the ITZ on the tensile strength of CRM was within one percent, which could be ignored. The influence of rubber particle size was investigated by analyzing CRM models containing five different rubber sizes from 0.86 mm to 7 mm. For each size, six different models with randomly distributed rubber particles were set up. CRM models presented a similar average strength even with different rubber particle sizes. However, the strength variation among the random models became higher when the rubber particle size increased. Numerical results also proved that treating rubber particles as pores in modeling led to negligible errors. Then, a prediction formula after considering the increase in air content is provided. Finally, the accuracy of numerical simulations was verified through a series of experimental studies.