Based on the unified strength theory as the yield criterion, an elastic-plastic constitutive model of autoclaved aerated concrete block (AACB) considering the intermediate principal stress was proposed. Meanwhile, the mechanical properties and failure mechanism of AACB were investigated by the uniaxial compressive, tensile, shear, and static triaxial compressive tests. The yield function based on the unified strength theory of AACB was derived. Moreover, the proposed model was integrated into the general finite element package ABAQUS by UMAT to simulate the deformation process of AACB under triaxial compressive. The numerical simulation results of AACB were in good accordance with but slightly larger than the static triaxial test results, which implied that the proposed constitutive model could be used to characterize the mechanical characteristics of AACB under complex stress states with high computational efficiency.

This paper aims to find the effects of viscosity on concrete behavior in pipelines. Concrete was prepared according to ACI 304.2R-96. Experiments were conducted for measuring its workability by means of slump test. Fluidity and rheology measurements of fresh mortar were investigated. The concrete behavior in pipes was directly investigated using computational fluid dynamics (CFD) simulation, which is based on the Eulerian approach and the dense discrete phase model (DDPM). Concrete behavior including flow profiles, aggregate distributions, and migration was analyzed and discussed. It was observed that the flow characteristic varies from shear flow to plug flow with increased viscosity, and the aggregate distribution along the central axis is more homogeneous. Aggregate radial migration is more pronounced with increased shearing time, decreased viscosity, and enlarged size of aggregates. It was also found that concrete between 12 and 22 Pa·s (1.74 × 10–3 and 3.19 × 10–3 psi·s) is more suitable for pumping.

ASTM C618 and AASHTO M 295 specifications for fly ash represent the primary documents used by U.S. state and federal agencies to determine the suitability of a fly ash source for use in concrete. Other countries have broadly similar specifications for fly ash. The article compares specifications from the United States, Canada, Europe, Australia, and New Zealand, noting similarities and differences. Despite its common use, several criticisms of the ASTM C618 specification exist and are discussed in this document. Specifically, concerns exist regarding its dependence on strength activity index testing for determination of fly ash reactivity and strength generation potential, and loss on ignition for quantification of unburnt carbon content, as these tests relate somewhat poorly to performance of the fly ash in concrete. Recently developed test methods that could improve some of the most problematic components of the ASTM C618 specification are discussed.

This study investigated the structural behavior of large-scale rubberized self-consolidating engineered cementitious composite (SCECC) beams designed to fail in shear. Specifically, the experimental program focused on the use of crumb rubber (CR) and powder rubber (PR) in SCECC as a partial replacement of silica sand at replacement levels of 0, 10, 20, and 30% (by volume). All cast SCECC, SCECC-CR, and SCECC-PR beams were compared with the performance of normal self-consolidating concrete (SCC) beam (containing coarse aggregates) at comparable compressive strength. The results obtained from this study included the fresh and mechanical properties of the developed mixtures, in addition to load-deflection curves, cracking behavior, first flexural crack load, diagonal crack load, ultimate load, ductility, and energy absorption capacity of the tested beams. The performance of some code-based equations in estimating the ultimate capacity and cracking moment of the tested beams was also evaluated. The results showed that all SCECC, SCECC-CR, and SCECC-PR beams exhibited higher performance compared to that exhibited by the normal SCC beam. However, the inclusion of either CR or PR in SCECC led to a reduction in the first crack load, diagonal crack, and ultimate load capacity of SCECC. The ductility and energy absorption capacity of SCECC was found to increase when 10% CR was introduced, while further increase in the percentage of CR decayed both the ductility and energy absorption capacity. On the other hand, the use of PR with up to 30% contributed to improving the deformability of the SCECC beam with no significant loss in its load-carrying capacity, thus providing a sustainable composite with higher ductility and energy absorption.

To promote the application of pervious concrete (PC) in heavy-duty pavement engineering, a thick plate (approximately 50 to 100 cm) paving structure can be used, and its failure form mainly by fatigue compression. Therefore, compressive fatigue tests were carried out under fatigue loads in four stress levels (S): 0.6, 0.7, 0.8, and 0.9, at three loading frequencies of 10, 15, and 20 Hz. The results showed that the fatigue life (N) and fatigue residual strength are controlled by S, while loading frequency showed no statistically significant effect on them. The fatigue failure of PC will not occur under a stress level of 0.6. The survival rate of PC and the fatigue life of uniaxial compression obey a Weibull distribution with two parameters. The material constants of uniaxial compression fatigue of PC are 0.0464 to 0.052, which are similar to ordinary concrete. There are two forms of fatigue failure: one is the shearing along the vertical central axis and the other is shear failure at an angle of 15 to 30 degrees with the vertical central axis.