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The size effect is one of the primary structural characteristics exhibited in reinforced concrete (RC) members in shear. Even though numerous studies have been conducted on masonry walls under shear, very few studies have been conducted that definitively answer whether a size effect exists for masonry walls. Diagonal compression tests on two groups of masonry walls with different dimensions were conducted to investigate the size effect on concrete brick masonry walls. A total of sixty masonry wall panels were tested. Five bed-joint mortar mix properties were used for each specimen. Test results showed that four failure modes were observed: diagonal tension failure, combined failure, sliding failure, and toe-crushing failure. In particular, the diagonal tension strength was significantly related to the specimen size. The larger specimen size led to a lower shear strength. Also, the shear modulus was highly dependent on the specimen size. Through experimentation, this study demonstrated that masonry walls exhibit a size effect. Moreover, the size effect is valid only in cases of diagonal tension failure. Based on the test results, this study revealed a correlation between diagonal tension strength and wall size. Lastly, the adequacy of the predictions was compared to the existing masonry codes. • This study aims to investigate the size effect on concrete brick masonry walls. • The existence of a size effect on masonry walls under shear is experimentally proved. • The size effect is valid only in cases of diagonal tension failure. • A correlation between diagonal tension strength and wall size is revealed. [ABSTRACT FROM AUTHOR]

To examine the dynamic characteristics of clay compounded with rubber particles, a series of resonance column experiments has been designed and performed on the rubber particle-clay mixtures (RPC) with varying rubber particle contents, rubber particle sizes, and confining pressures. The analytical method for the skeleton void ratio of RPC was proposed according to its micro-contact structure, and a prediction model was suggested to anticipate the maximum dynamic shear modulus relying on the skeleton void ratio. Furthermore, empirical prediction models were established to anticipate the dynamic shear modulus ratio and damping ratio of RPC. The findings indicated that the maximum shear modulus and shear modulus ratio will decrease with increasing rubber content, and decreasing rubber particle size and confining pressure. The findings also show that the damping ratio will increase with increasing rubber content, and decreasing rubber particle size and confining pressure. Considering good damping ratio of the RPC compared with pure clay, the RPC has good application prospects in the field of vibration isolation and reduction, and the obtained results here will provide appropriate and scientific guidance for the application of RPC. • The skeleton void ratio was developed based on the micro-contact structure of rubber particle -clay mixtures. • Models were proposed to predict the maximum shear modulus, dynamic shear modulus ratio and damping ratio of mixtures. • The maximum shear modulus and shear modulus ratio decreased as rubber content increased and rubber particle size decreased. • The damping ratio increased as rubber content increased and rubber particle size decreased. [ABSTRACT FROM AUTHOR]

The assessment of the shear modulus (G) of municipal solid waste (MSW) and leachate-contaminated soil (LCS) is of vital importance for landfill engineering investigation and achieving sustainable development goals. In this study, 153 cyclic triaxial tests on MSW (reconstructed samples under CU conditions) and 104 cyclic simple shear tests (strain controlled) on LCS were conducted to assess the shear modulus. The examined variables are plastic percentage (0–0.274), age (0–16 years), shear strain (0.075–3.63%), unit weight (9 and 12 KPa), frequency (0.1–1 Hz), and confining pressure (75 and 150 KPa) for MSW and leachate content (0–40%), shear strain (0.05–1%), frequency (0.1 and 1 Hz), and vertical load (50–350 KPa) for LCS. Laboratory assessment of cyclic parameters is costly and complicated which requires precise testing and the experts. Therefore, multiple types of ensemble models (AdaBoost, GBRT, XGBoost, and Random Forest (RF)) were utilized along with Forensic-Based Investigation Optimization (FBIO). The application of numerical and computational approaches as the main novelty of the research can be a step forward to save time and money. The performance comparison of the established models on experimental datasets showed that GBRT- FBIO model outperformed the other models for G-MSW (R2 =0.99, RMSE=0.164, MAE=0.122, MAPE=0.073, and a20-index=0.956 for testing datasets) and G-LCS (R2 =0.99, RMSE=0.477, MAE=0.385, MAPE=0.028, and a20-index=1 for testing datasets). Finally, the outcomes of the sensitivity analysis also displayed the most participation of shear strain (50.87%) and vertical load (52.1%) to the shear modulus of MSW and LCS. [Display omitted] • Shear modulus evaluation of municipal solid waste and leachate contaminated soil. • Implement ensemble learners hybridized with forensic-based investigation optimization. • Perform validity and sensitivity study to determine each variable's contribution. • The performance showed that GBRT models outperformed in G-MSW and G-LCS. [ABSTRACT FROM AUTHOR]

Due to the huge amount of annual non-renewable ceramic waste disposal, it is in favor of eco-system to reuse the ceramic waste in earthwork structures. Thus, among several different applications of ceramic components, they can also be used to replace aggregates in the core of embankment dams, waste disposal projects and to form subgrade of roads and railways. The main issues addressed in this study are the effect of the volumetric content and size of the ceramic inclusions on the mechanical properties of ceramic-clay mixtures. Using an experimental approach, strain-controlled monotonic, stress-controlled cyclic, and post-cyclic monotonic triaxial undrained tests were made. The innovation of this study is that sphere beads of ceramic with different diameters were added to low-plastic clay to explore the role of bead size on the mechanical properties of bead and clay mixtures under monotonic, cyclic and post-cyclic loadings. Thus, we tested four types of specimens consisting of merely pure clay, 80% clay–20% bead, 60% clay–40% bead, and 40% clay–60% bead. Scanning electron microscope (SEM) images were additionally used to investigate the fabric of the clay between the ceramic beads. Test results revealed, firstly, that effective friction angle and undrained shear strength increase with the bead content. Secondly, dilative behavior was captured in all the bead and clay mixtures. Further, both dynamic shear modulus and damping ratio increase with the bead content. Similarly, post-cyclic shear strength increases with the bead content. Finally, different bead diameters did not change the observed trend. • Iran is among top producers of ceramic tile in the world, with considerable amount of annual non-renewable ceramic waste accumulation. • It is in favor of eco-system to reuse the ceramic waste in earthwork structures. • This study shows that an addition of ceramic grains to low-plastic clay improves its mechanical specifications. • Effective friction angle, undrained shear strength, dynamic shear modulus, damping ratio and post-cyclic shear strength increase with the increase of bead content. • Results of the study show that the content of the bead significantly affects the behavior of the mixture of the bead and clay, regardless of the bead diameter. [ABSTRACT FROM AUTHOR]

• The shear behavior of three types of RAC was investigated. • The effect of content and type of RCA on shear behavior of RAC were analyzed. • The shear stress-strain constitutive models for three types of RAC were proposed. • Four calculation formulas for shear modulus of RAC were established. This paper studied the shear behavior of three types of recycled aggregate concrete with different replacement levels of recycled coarse aggregate. Sixty cube specimens and thirty beam specimens with uniform depth and varying width were designed to test their mechanical parameters including cube compressive strength, splitting tensile strength, shear strength, peak shear strain, shear stress-strain curves, and shear modulus. We analyzed how these parameters are influenced by the type of recycled coarse aggregate and by recycled coarse aggregate replacement level. We established the strength conversion equations, one-parameter polynomial non-dimensional shear stress-strain equations, and shear modulus calculation formulas of three types of recycled aggregate concrete. It is found that the strength of recycled aggregate concrete I isslightly lower than that of conventional concrete and decrease with the increase of recycled coarse aggregate replacement level. However, the strength of recycled aggregate concrete II and recycled aggregate concrete III is slightly higher than that of conventional concrete when the recycled coarse aggregate replacement ratio is less than 70%. As the recycled coarse aggregate replacement ratio increase, the peak shear strain of three types of recycled aggregate concrete gradually decreases. The shear strength and peak scant shear modulus of three types of recycled aggregate concrete show the rule of recycled aggregate concrete III > recycled aggregate concrete II > recycled aggregate concrete I. Furthermore, the calculated values of several equations established by the authors agree well with the test values. [ABSTRACT FROM AUTHOR]

• A new dynamic and a new static method for testing shear modulus of OSB are proposed, respectively. • Relationship of mode shape coefficient with length-width and width-thickness ratios is given. • The static square-plate torsional test for shear modulus of orthotropic materials is described. • The scheme of pasting the strain gauges in the direction of ±45° is proposed. • The new dynamic method of testing OSB shear modulus is verified by static square-plate torsion. • The result indicates the orthotropy of OSB and it is not simply a unidirectional composite. In this work, a new dynamic and a new static method for testing shear modulus of oriented strand board (OSB) are proposed, respectively. ANSYS software was used to calculate the mode shape coefficient of the OSB free plate and cantilever plate specimens, and the relationship of the mode shape coefficient depending on the length-to-width and the width-to-thickness ratios of the plate specimen was given. According to the stress and strain analysis of static torsion of the square plate, the principle of static square-plate torsional test for testing the shear modulus of orthotropic materials was described and the scheme of pasting the strain gauges in the direction of ±45° was proposed to ensure the accuracy of testing static shear modulus of OSB. The correctness of the new method for dynamically testing OSB shear modulus was verified by static square-plate torsional test. The longitudinal elastic modulus E x , transverse elastic modulus E y , elastic modulus in the 45° direction E 45° , shear modulus in the plane G xy and shear modulus in the 45° direction G 45° were measured dynamically. The measured results of E x /E y = 2.88 and G 45° < G xy for OSB indicate that the orthotropy of OSB cannot be simply dealt with as a unidirectional composite. [ABSTRACT FROM AUTHOR]

• CTB containing RAP and CTB virgin aggregates resist similarly to cyclic loadings. • CTB-RAP shows a slightly lower mechanical strength than CTB-Virgin. • CTB-Virgin shows a much more rigid behaviour than CTB-RAP. • The CTB-Virgin shows a faster damage growth than the CTB-RAP. • The use of RAP in CTB mixtures does not modify mechanical performance of the mix. A laboratory investigation was performed to better understand the performance of Cement-Treated Base (CTB) mixtures containing Recycled Asphalt Pavement (RAP) during a long-lasting service period. Two CTB mixtures, one containing only virgin aggregates and the other containing RAP and virgin aggregates, were tested by triaxial tests (static and cyclic) and resonant column tests to evaluate stiffness and dampening at very small deformations. Similar mechanical properties and response to cyclic loadings were obtained for the two mixtures. The results led to the conclusion that the use of RAP as a replacement for virgin aggregates for a CTB mixture does not cause any significant alteration in terms of mechanical performance. [ABSTRACT FROM AUTHOR]

In this work, the principle and method for synchronous dynamic measurement of elasticity, shear modulus and Poisson’s ratio of wood and wood composite with two strain gauges were studied and discussed. The experimental scheme, named 0°–75° scheme, was developed for synchronous dynamic measurement of elasticity ( E ), shear modulus ( G ) and Poisson’s ratio ( μ ) with two strain gauges of 0° and 75°. The 75° strain gauge was not only used to measure Poisson’s ratio together with the 0° strain gauge, but also to measure the first-order torsional frequency of cantilever plate. In addition, the principle of measuring elasticity and shear modulus by the 0°–75° scheme was described. Based on the stress and strain analysis of first-order bending and torsional modes of cantilever plates, the pasting position and orientation of strain gauges in the 0°–75° scheme were decided. Comparing the results of using two combinations of strain gauges, 0°–75° and 0°–90° schemes, the correspondence indicates that the 0°–75° scheme is feasible for dynamic measurement of Poisson’s ratio. By transient excitation, the strain spectrums under 0° and 75° of Poplar’s tangential section, Sitka spruce’s radial section and medium density fiberboard (MDF) cantilever plate were measured. Thus, one-hammer-excitation synchronous measurement of elasticity, shear modulus and Poisson’s ratio of materials was achieved. Its correctness was verified by axial tension and static square-plate torsion tests. [ABSTRACT FROM AUTHOR]

Microscopic aggregate–mastic interaction and adhesion lead to macroscopic modulus nonuniformity of asphalt mastic on aggregate surface. This nonuniformity is ignored in multiscale models of mixture and causes prediction errors. This study aimed to establish a macromechanical model considering microscopic aggregate–mastic interaction and adhesion to characterize the mastic modulus in contact with aggregate substrates. Frequency sweep tests were conducted to measure the modulus of mastic with different thicknesses, and the measured mastic was simplified as a mechanical model comprising viscoelastic elements series. By introducing a piecewise function of thickness, the measured modulus was deduced as an expression containing the contribution of the affected layer and bulk phase. Four model parameters described the microscopic interaction, adhesion, affected range, and modulus of bulk mastic, respectively. The model was applied to the mastic modulus on different substrates, and results effectively demonstrated the applicability. The temperature and frequency dependence and time–temperature superposition of interface mastic modulus and bulk mastic modulus were observed, and it demonstrated the model’s ability to characterize mastic viscoelasticity. Moreover, evaluation of the gap between the measured and real moduli on a substrate showed the necessity of considering interaction and adhesion. [ABSTRACT FROM AUTHOR]

The objectives of this study are, 1) to simulate asphalt binder modified with exfoliated multi-layered graphite nanoplatelets (xGNP) using the Molecular Dynamics (MD) method, and 2) to analyze different modulus properties of these asphalt binder models compared with those of the control asphalt binder model. The multi-layered graphene model was used to represent the xGNP particles, which were used to modify the control asphalt in the laboratory. The three-component control asphalt binder model was used as in the authors’ previous study. The xGNP modified asphalt binder model was built by incorporating the xGNP model and control asphalt binder model and controlling mass ratios to represent the laboratory prepared samples. After the xGNP modified asphalt binder model was generated, the densities of the control and xGNP modified asphalt binder models were computed and verified. Mechanical properties of these models were simulated and calculated in MD simulations using procedures similar to those in the experiments, which include the bulk modulus, Young’s modulus, shear modulus and Poisson’s ratio. The simulation results indicate that the temperature-modulus trends of these asphalt binder models were comparable to those of the laboratory data. The MD simulation data were larger than the laboratory results due to limitations of the current MD simulation, which are discussed in this study. In addition, Poisson’s ratios calculated from the MD simulations coincided with the laboratory results. [ABSTRACT FROM AUTHOR]

In this work, the first-order torsional mode shape functions in both directions vertical and parallel to the middle plane of cantilever plate were obtained according to ANSYS software and the optimization principle. The coupling equation of elastic modulus, shear modulus and first-order torsional frequency of cantilever plate was derived with the aid of energy method. The integral of the two mode shape coefficients in the equation, kinetic energy, torsional strain energy and tensile-compressive strain energy were computed. The calculated value was then conducted with binary linear regression to derive the relationship of mode shape coefficient with width-to-length and height-to-width ratios. The correctness of coupling equation was verified by dynamic and static tests of isotropic materials and lumbers of various tree species. The method of measuring shear modulus by frequency spectrum of cantilever plate was proposed and it has advantages of convenience, celerity and good repeatability. This method applies to testing shear modulus of isotropic materials and three main-direction shear modulus ( G LT , G LR and G RT ) of timbers. [ABSTRACT FROM AUTHOR]

This paper studied the shear behavior of concrete with different levels of recycled coarse aggregate (i.e., 0%, 50% and 100%) after being subjected to different temperatures (i.e., 20 °C, 200 °C, 300 °C and 400 °C). Thirty-six beam specimens with uniform depth and varying width were designed to test their mechanical parameters including shear strength, peak shear strain, stress–strain curves and shear modulus. We analyze how these parameters are influenced by recycled coarse aggregate (RCA) content and by high temperature. We establish the shear stress–strain equations for RCA-embedded concrete after exposure to different temperatures. It is found that the aforementioned mechanical parameters are minimally influenced by the RCA content at ambient temperature (about 20 °C). After exposure to high temperatures, the RCA content affects the shear strength insignificantly but increases the peak strain slightly. As the temperature elevates, the residual shear strength and shear modulus decline rapidly whereas the peak strain increases linearly. Furthermore, the normalized shear stress–strain curves become more disperse with the increment of temperature. [ABSTRACT FROM AUTHOR]

• Side methyl groups in PTGL hindered the crystallization of soft segments in PUE. • Shear modulus of PUE decreased with incorporating PTGL at subzero temperatures. • HPEB prepared with new PUE still exhibited high enough vertical bearing capacity. • Adding PTGL could significantly improve the low-temperature resistance of HPEB. Seismic isolation laminated elastomeric bearings are applied worldwide in bridges to reduce vibration and prevent collapse. Currently, the high-capacity polyurethane elastomeric bearings (HPEB) are favored in long-span bridges due to their super-high bearing capacity, low cost, and simple manufacturing process. However, there are many countries and regions in the world with extremely cold climates and are covered by ice and snow. At subzero temperatures, the stiffness of polyurethane elastomers (PUEs), which are an important component of HPEB, increases significantly, rendering HPEB ineffective in protecting bridges in cold regions from earthquake hazards. In this work, an attempt was made to modify the PUE as well as to improve the low-temperature resistance of HPEB by introducing 3-methyl-tetrahydrofuran/tetrahydrofuran co-polyether glycol (PTGL). Specifically, a series of microscopic characterization experiments (FT-IR, AFM, DSC, and DMA) were performed to study microphase separation and crystallization phenomena of the newly developed PUE. Moreover, the mechanical verification experiments were performed for the PUE and HPEB with different amounts of PTGL, including tensile, compression, and shear tests. All tests are performed at 23, 0, −10, and −20 °C temperatures respectively. The mechanical experiments demonstrate that the introduction of PTGL significantly reduces the shear modulus (G) and horizontal stiffness (K h) of HPEB at low temperatures, that is, improves the low-temperature resistance of HPEB. Therefore, this research is of great significance for the application of isolation bearings in cold regions. [ABSTRACT FROM AUTHOR]

• Small-strain dynamic properties of polyester and hemp MICP-fiber combined reinforced calcareous sand were studied. • The maximum dynamic shear modulus is positively correlated with the calcium carbonate with the increase of fiber content. • Fibers and its content accelerate the stiffness degradation of MICP cemented calcareous sand based on the bonding between fibers and calcareous sand. • Hemp fiber with rougher surface results in greater damping ratio of MICP cemented calcareous sand than polyester fiber by AFM test. Microbially induced calcite precipitation (MICP)–fiber combined reinforcement through the addition of fibers during the MICP process is a novel, natural, and green technique for foundation improvement, which can effectively enhance the mechanical properties of cemented soil. However, the small-strain dynamic properties of this method remain unexplored. The effects of different polyester fiber and hemp fiber contents (0%, 0.1%, 0.2%, and 0.4%) on the dynamic properties of the MICP–fiber combined reinforced calcareous sand under small-strain conditions were studied using resonant column tests, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The maximum dynamic shear modulus of the MICP–fiber combined reinforced calcareous sand under small-strain increases with the fiber content; the stiffness degradation rate of the dynamic shear modulus ratio of the test sample increases with the addition of two types of fibers, and the addition of hemp fibers greatly boosts the increase rate of the damping ratio. The SEM results indicate that excessive fibers distributed between the sand particles occupy the nucleation sites of bacteria, hinder the bonding between sand particles, and ultimately affect the dynamic shear modulus parameters of the sample. The AFM results show that the hemp fiber has much greater surface roughness than the polyester fiber. Therefore, the change rate of the damping ratio of the hemp fiber-doped MICP–fiber combined reinforced calcareous sand is much greater than that of the polyester fiber-doped sample. This is the first report on the basic mechanism of the small-strain dynamic properties of the MICP–fiber combined reinforced calcareous sand with different fiber contents and types. Furthermore, it provides a new theoretical basis for related research on improving the dynamic properties of sand thus reinforced. [ABSTRACT FROM AUTHOR]

• Comparison of experimental approaches to measuring rolling shear properties of CLT. • Rolling shear modulus is effected by annual ring orientation more than by aspect ratio. • Load direction has substantial effect on rolling shear strength. • Digital image correlation approach recommended to identify and avoid measurement errors. The structural behaviour of a cross laminated timber (CLT) system is dictated in-part by the rolling shear properties (both strength f r and modulus G r) of its laminates. To investigate the rolling shear properties of CLT, short-span four-point bending tests, modified planar shear (MPS) tests with timber sandwich plates, and MPS tests with steel sandwich plates were conducted on Australian grown Eucalyptus nitens and radiata pine, as well as European grown Norway spruce. A strong positive relationship between aspect ratio and strength was found, which agrees with previous research. However, the annual ring orientation distribution rather than the aspect ratio was shown to have the most pronounced effect on the shear modulus. The load direction, which has not been accounted for by researchers, was shown to have a substantial effect on the measured rolling shear strength. When the applied load direction was parallel to the annual rings, the Eucalyptus nitens, radiata pine and Norway spruce specimens exhibited rolling shear strengths of 4.1, 2.7 and 1.7 MPa respectively. These average recorded strengths were found to decrease by 16%, 40% and 52% respectively when the load direction was changed to run perpendicular to the rings instead. By directly measuring the shear deformations of two specimens tested under different MPS approaches using Digital Image Correlation (DIC), the impact of the plate material on the recorded shear modulus was isolated. This revealed that the MPS tests with steel plates recorded average rolling shear modulus values which were as much as 42% higher than their counterparts with timber plates, as well as identifying substantial errors in laser and LVDT-like measurement tools. It is recommended that a DIC approach is employed to complement or replace a UTM or laser sensor deformation measurement approach to mitigate these potential errors. [ABSTRACT FROM AUTHOR]

Abstract: The seismic behaviour of asphaltic concrete used as an impervious core in embankment dams was investigated. To evaluate the specimen’s dynamic behaviour, an extensive series of monotonic and cyclic triaxial tests were carried out. Bitumen content between 5.5% and 7.0% with 0.5% increments were selected for the tests. Isotropic and anisotropic initial stress conditions with different principal stress ratio were also considered in this study. Thousands of cycles were imposed on some of the specimens, to study their fatigue behaviour due to seismic loading. A small degradation could be seen but no cracking was observed on the cutting surfaces. All tests were carried out at a constant temperature of 22°C simulating a constant temperature inside a dam in tropical climate regions. Shear modulus in the compression region (Gc ) and tension region (Ge ) are presented for different Bitumen content, confining stress, stress ratio (Kc ) and loading type. The damping ratio was also presented for different loading states. A regression equation was also derived for determining cyclic and maximum shear modulus (G max) of the asphaltic concrete for different Bitumen content as a function of confining stress which can be used in numerical studies. [Copyright &y& Elsevier]

• V-notched rail shear tests and DMA tests are conducted. • Shear stress – shear strain curves at room temperature are obtained. • The effects of temperature, time, and strain rate are evaluated. • Transition temperature associated with modulus decline is suggested to be 30°C. • A long-term loading test is simulated adopting the proposed TTS equation. The transparent ionomer material SentryGlas® or SG for short is widely used as interlayers in laminated glass and is also a potential adhesive in laminated connection. The material's shear modulus is of practical interest before glass breakage because it allows a shear transfer between glass components. Due to the viscoelasticity behaviour of the material, its modulus is significantly dependent on the working conditions. This work investigates the effects of temperature, time, and strain rate on SG's shear small-strain modulus from the point of practical application. The shear property at room temperature is obtained from the results of shear tests. Based on the viscoelastic theory, the time and temperature dependence within the actual application range is quantitively determined from DMA measurements. The glass transition temperature associated with modulus decline is then recalibrated. The effect of strain rate is also qualitatively measured. Finally, the time-temperature dependent equations of shear modulus are applied to numerical simulation of a long-term loading test on framed ionomer interlayer laminated glass. [ABSTRACT FROM AUTHOR]

• The interfacial properties of polymer and concrete was investigated by a newly designed apparatus. • A series of monotonic, cyclic and post-cyclic direct shear tests were carried out. • The effect of vertical stress shear rata, cycle number on interface characteristics were studied. The safety performance of geotechnical engineering is obviously affected by the interface characteristics of geotechnical materials. With widely use of the polymer in geotechnical engineering, the investigation for interface characteristics of polymer and concrete structure is necessary. In this paper, to investigate the interfacial shear properties of non-water reacted polymer and cement concrete, a series of displacement controlled monotonic direct shear (MDS) tests, cyclic direct shear tests (CDS) and post cyclic direct shear (PCDS) tests were carried out by using a newly designed direct shear test apparatus. The compressive strength of the polymer and cement concrete blocks are 2 MPa and 20 MPa respectively. The effects of vertical stress (50 kPa, 100 kPa, 150 kPa, 200 kPa), shear rate (1 mm/min, 2 mm/min, 3 mm/min, 4 mm/min and 5 mm/min), and cycle number on the investigated interface characteristics were studied. The results show that, with the increase of the vertical stress, the average peak shear stress of the interface gradually increases. As the vertical stress increase from 50 kPa to 200 kPa, the average peak shear stress increased by more than two times under various conditions. While with the increase of the shear rate, the average peak shear stress of the interface gradually decreases, but the reduction is small. And the reductions are all not more than 10% when the shear rate increases from 1 mm/min to 5 mm/min under all conditions; with the increase of the number of cycles, the average peak shear stress of the interface gradually decreases, and the decrease rate gradually decreases. When the vertical stress is 100 kPa and the shear rate is 3 mm/min, the average peak shear stress is reduced by 4.4% as the number of cycles increases from 1 to 5, while that is reduced by 1.2% as the number of cycles increases from 5 to 10; Under the given shear rate and vertical stress, the interface between polymer and cement concrete shows the shear softening in both MDS test and PCDS test. However, under the same vertical stress and shear rate, the shear strength and shear modulus of the MDS tests are greater than those of the PCDS tests. While the differences for MDS and PCDS are almost all not more than 5 kPa; with the increase of vertical stress, the shear strength and shear modulus of MDS test and PCDS test increase gradually. The shear strength increased by more than two times and the shear modulus increased by more than one times as the vertical stress increases from 50 kPa to 200 kPa. The shear strength is reduced by not more than 6% and the shear modulus is reduced by not more than 11% as the shear rates increase from 1 mm/min to 5 mm/min. The apparent cohesions are obviously influenced by cyclic direct shear, while the effective friction angles are a little influenced by CDS. [ABSTRACT FROM AUTHOR]

• Diagonal compression tests on double-wythe Flemish bond masonry walls are presented. • Simulation of the diagonal compression test with an enhanced continuum FE model. • The diagonal compression test is interpreted in the linear and nonlinear range. • A coefficient of 0.4 is found adequate to compute the tensile strength of masonry. • The coefficient shows little sensitivity to panel size and size of loading shoes. The masonry tensile strength and shear modulus play a key role in the definition of the shear capacity of masonry structures. These properties are often determined experimentally by means of the diagonal compression test on square walls, which is regulated by the ASTM E519 standard. In spite of its wide use, the interpretation of the test is still controversial and no universal criterion exists on how to derive the masonry mechanical properties from the wall overall strength. Aiming to contribute in the improvement of the test's reliability and interpretation, this paper presents an investigation on the use of the diagonal compression test to characterise the shear properties of masonry. First, an experimental campaign on brickwork walls is described. The walls were built in laboratory in Flemish bond, a pattern that has been scarcely investigated in the available research studies on this type of test. Second, an advanced numerical model is used for the analysis of walls subjected to the diagonal compression test. The adopted numerical model, enhanced by a crack-tracking algorithm to reproduce accurately the tensile damage localization, constitutes a very useful and powerful tool to interpret correctly the behaviour during the test. Finite element analysis was executed to interpret the walls' response in the linear and nonlinear ranges with models properly calibrated by comparison with the experimental results. As a result, a criterion was determined for the calculation of the tensile strength from the outcomes of the diagonal compression test. A sensitivity analysis was carried out with regard to the most influent material properties of the material, the geometrical dimensions of the panel, and the loading conditions of the testing setup. The findings of this research were finally applied and validated by means of simulations of diagonal compression tests from eight experimental campaigns performed by other authors on different masonry typologies. [ABSTRACT FROM AUTHOR]

• Static and dynamic characteristics of granulated rubber-sand mixtures are studied. • The optimum granulated rubber content is obtained. • New equations for calculating q f and G max are established, respectively. Because of their low unit weight, strong linear elastic deformation ability, good durability and high energy dissipation, mixtures of waste tire rubber and sand have been increasingly used as a new type of subgrade filler in railway engineering. To investigate static and dynamic characteristics of granulated rubber-sand mixtures as a new filler, consolidated undrained monotonic and cyclic triaxial tests were carried out. The monotonic triaxial tests reveal that the shear strength of mixtures first increases and then decreases with increasing granulated rubber content and is maximized when the rubber content is approximately 10%. Based on the theory of an equivalent intergranular void ratio, a new equation for estimating the peak deviatoric stress of mixtures is proposed. The cyclic triaxial tests reveal that the addition of granulated rubber can constrain the generation and accumulation of dynamic pore water pressure and improve the liquefaction resistance of mixtures. The change in shear modulus is inversely proportional to the change in granulated rubber content and frequency, and directly proportional to the change in confining pressure. A new equation is also established for calculating the maximum shear modulus considering the effect of the equivalent intergranular void ratio and confining pressure. By comparing the maximum shear modulus of the new railway subgrade filler with that of other subgrade filler, it is concluded that a granulated rubber content of less than 20% can meet engineering requirements related to shear stiffness. The damping ratio is correlated with granulated rubber content, negatively correlated with confining pressure and insensitive to loading frequency. The relationship between the damping ratio and shear strain conforms to the equation proposed by Hardin and Drnevich. Based on the analysis of static and dynamic characteristics of granulated rubber-sand mixtures with different rubber content, the optimum granulated rubber content should be approximately 10%. [ABSTRACT FROM AUTHOR]

• G max and M increased by 40% and 20%, respectively due to the presence of sand. • Dynamic Poisson's ratio depends on curing time, binding water content and modified cement content. • L/λ ratio of 4 is required to negate the near-field effect in BE testing. • A G max prediction model is proposed and validated. This study aims to investigate the effect of sand in the cemented clay matrix by understanding the limitations of conventional mixture design concepts. To characterize the behaviour of cemented sandy clay, an extensive experimental study was conducted based on bender element (BE) testing and ultrasonic pulse velocity (UPV) testing. Scanning electron microscope image showed that stiffer sand particle bonded to the cemented clay matrix caused the increase in stiffness. The velocity ratio and thereby dynamic Poisson's ratio reduced with the increase in stiffness of cemented soil. Finally, a predication model is proposed to estimate the shear modulus and validated with the data obtained from literature for other soil and cement types. [ABSTRACT FROM AUTHOR]

• Twenty-one UDVW specimens were designed to test shear performance. • The strength enhancement parameter β was proposed and calculated. • The calculation method of shear stress-strain and shear modulus were established. This paper presents a study on the shear performance of two different high-performance chopped fibers (basalt fiber and polyacrylonitrile fiber) employed to reinforce lightweight aggregate concrete. Environmentally friendly supplementary cementitious materials, fly ash and silica fume, are used to substitute a part of cement. Around 21 UDVW specimens are designed to test shear performance. The relationships between the shear strength and the cube compressive strength, splitting strength, flexural strength, and specific strength are established. Although the addition of the fibers does not change the shear failure morphologies, but could change the development direction of the cracks. Moreover, the fibers increase both the peak shear stress and the peak shear strain, and corresponding calculation models are proposed to predict these properties using the coefficient of shear strength enhancement β s. When the fiber content reaches 1% and 1.5%, the normalized shear stress–strain compared wrapped that of plain specimen notably. With an increase in the fiber content, the peak secant shear modulus decreases slightly, whereas the initial tangent shear modulus increases. Moreover, calculation methods are established to compute the peak secant shear modulus and the initial tangent shear modulus. The calculated results of several equations in this study present excellent agreement with the test results. [ABSTRACT FROM AUTHOR]

• Dynamic behavior of a coarse sand mixed with crumb rubber was investigated. • Dynamic parameters of mixtures were affected by rubber content and confining stress. • Adding rubber increased damping at strains lower than a threshold strain value. • Adding rubber decreased damping at strains larger than a threshold strain value. • The threshold strain value depended on the applied confining stress. Different additives can be utilized to improve the mechanical behavior of soils including their dynamic properties. Among these additives, crumb rubber, as a recycled material, can provide economic and environmental advantages in addition to the improved mechanical behavior. In this paper, different aspects of dynamic behavior of sand-rubber mixtures were investigated over a wide range of shear strains implementing dynamic hollow cylinder tests. For this purpose, the effects of various parameters including relative density, rubber content, confining stress, and size of rubber particles were studied in detail. The results demonstrated that dynamic properties of sand-crumb rubber mixtures were mainly influenced by rubber content and confining stress values, while relative density and rubber particle size were less effective in this regard. Moreover, it was found that dynamic behavior of the mixtures was completely strain-dependent such that at strain ranges lower than a threshold value, which depended on the applied confining stress, an increase in rubber content led to higher damping ratios, while at strain levels higher than the threshold value a reverse trend was observed. [ABSTRACT FROM AUTHOR]

• An asphalt mixture shear modulus model is proposed based on granular mechanics theory. • The model was verified with an asphalt mixture analysis system and a pressure film. • Contact area, stress distribution, and total stress were measured accurately. • Our model quantified the binder and gradation effects on the asphalt's shear modulus. This study proposes a mechanical model for the shear modulus of asphalt mixtures based on granular mechanics theory. An aggregate interface shear test is conducted to validate the proposed model with the asphalt mixture particle shear analysis system and a pressure film. Results show that the pressure film can measure accurately the contact area, stress distribution, and total stress of the contact interface. It is demonstrated that more than 65% of the contact area bears only 37.5% of the total load, and the contact interface exhibits an uneven stress distribution. The binder type has a significant influence on the shear force at the contact interface. As the penetration of the asphalt decreases, the softening-point temperature increases; as the rutting factor increases, the tangential elastic stiffness also increases. The proposed mechanical model can distinguish the influences of the binder and gradation on the shear modulus of asphalt mixtures. [ABSTRACT FROM AUTHOR]