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Benefiting from its excellent sustainable plastic carrying capacity, rubberized concrete (RuC) has received extensive attention. In this study, the dependency of rubber aggregate (RA) particle size influencing factor on content is investigated through quasi-static compression tests. The results demonstrate that the influence of RA particle size on stress–strain behavior of RuC shows a content-dependent effect. The postpeak stress-buffering area and strain-softening area of RuC reduce significantly with the increase of RA particle size at higher RA contents. Moreover, the corresponding rubber aggregate influencing factor (RIF) model is established. The constitutive model of RuC is proposed by introducing the RIF model into the characteristic parameters. Finally, the stress–strain relationship of RuC is predicted by using the proposed constitutive model. It is concluded that the proposed constitutive model can be further applied to the structural design optimization of RuC. [ABSTRACT FROM AUTHOR]

• A new avenue to prepare rubber aggregate with excellent interfacial adhesion and compatibility was developed by combining ultrasonic mechanochemistry and a modified slurry coating. • The interface between rubber particles and cement matrix was improved and the mechanical properties were vastly enhanced. • The modification of rubber powder significantly improved the abrasion resistance of crumb rubber concrete. • The abrasion mechanism of CRC was systematically analyzed and the abrasion mechanism models of the rigid and semi-rigid body were established. • The interface between rubber particles and cement matrix played an important role in controlling the abrasion resistance of CRC. The abrasion resistance of crumb rubber concrete (CRC) has always been a research hotspot. However, the large reduction in the mechanical properties of CRC limits the improvement of its abrasion resistance. In this study, a new method of modifying waste rubber powder (WRP) combining mechanochemical action, ultrasonic energy accumulation and the coating effect of the modified slurry was proposed. The mechanical properties of CRC with rubber volume fractions of 0%, 15%, 25% and 35% were determined. The abrasion resistance of CRC was studied by the ball bearing and ball milling methods. The abrasion mechanism of CRC was analysed, and abrasion mechanism models of the rigid and semirigid bodies were established. The results showed that the compressive and flexural strengths of modified CRC (MCRC) were increased by 74.2% and 45.7% respectively, compared with CRC. The abrasion resistance of concrete first increases and then decreases with increasing rubber content. Compared to the control concrete, the abrasion resistance of CRC and MCRC was increased by 14.9% and 24.8%, respectively. The mass loss rates of CRC and MCRC were 29.78% and 24.98% respectively, under the same volume replacement. The enhancement of abrasion resistance of the CRC is mainly due to the absorption of wear energy by rubber. The rubber-cement matrix (R-CM) interface played an important role in controlling the abrasion resistance of CRC. [ABSTRACT FROM AUTHOR]

• An improved model based on Mori-Tanaka method is proposed to predict the elastic modulus of crumb rubber concrete. • The importance of characteristic strain of ordinary aggregates and rubber crumbs is included in the model. • The prediction is more realistic with the effect of pore is introduced into concrete model when the rubber crumbs is contained. • The importance of the factors for the elastic modulus prediction of crumb rubber concrete can be evaluated by this model. Crumb rubber concrete (CRC) has attracted significant attention as a typical reclamation and recycling of solid wastes, and endows concrete with excellent impact resistance. However, the elastic modulus of CRC can be affected by the uncertain properties of rubber crumbs. In this study, an improved Mori-Tanaka model (IMT) was proposed to estimate the elastic modulus of CRC in meso-scale. The model establishes the quantitative relationship between the elastic modulus and volume fraction of all constituent materials (ordinary aggregate, rubber crumbs, and cementitious materials) involved in CRC and its interface transition zone (ITZ). The results indicate that the error of IMT predicted elastic modulus of CRC is about 3.9%, which is reduced by about 8.9% compared with the Mori-Tanaka model (MT model). Further, the importance of different factors influencing the elastic modulus of CRC is assessed by the IMT model. The specific attributes of rubber crumbs (particle size and volume fraction), ITZ, and cementitious materials (the elastic modulus) have been shown to affect the elastic modulus of CRC significantly. Thus, the IMT model can be beneficial for the design of CRC with specific elastic modulus by considering the effect of different constituents. [ABSTRACT FROM AUTHOR]

• A new image processing method is proposed for identifying micro-cracks in concrete using XCT. • The effect of uneven intensities in the XCT images was overcome. • Interference of rubber particles and pores on the results of crack detection was avoided. As a combination of a brittle cement matrix and ductile rubber particles, rubberized concrete has complex fracture characteristics at the microscale level. To better understand the fracture pattern of rubberized concrete, in this study, a novel image processing method is developed to extract the cracks in the specimens accurately, especially the microcracks, obtained in X-ray computed tomography images. To demonstrate the validity of the method, in-situ XCT tests were used to track the rubberized concrete specimens under loading. The robustness and practicability of the proposed method were verified by processing the images of the specimens with different rubber contents. The results show that the crack propagation under loading could be visualized by using the method, and the effect of the addition of the rubber on the cracks was then analyzed quantitatively. [ABSTRACT FROM AUTHOR]