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In this investigation, polymer concrete (PC) with three different epoxy resin contents, ordinary cement concrete (OCC), lightweight concrete (LWC), and lime-mortar soil (LMS) have been studied under uniaxial and triaxial compression tests to determine their mechanical behavior by measuring axial stress-strain and volumetric strain versus axial strain curves. According to the results, PC showed higher strength, ductility, and energy absorption than that of OCC and LWC. Then, nonlinear finite element analysis (NFEA) was implemented to predict the experimental results using hierarchical single-surface (HISS) failure criterion and disturbed state concept (DSC) to capture the elastoplastic behavior of concrete materials including volumetric strain. Moreover, the pattern of failure was estimated using ultimate disturbance values obtained from the model, followed by comparison with the experimental and Mohr-Coulomb failure patterns. The proposed model is applicable to a variety of materials with different behavior, and its prediction is in good accordance with experimental results. [ABSTRACT FROM AUTHOR]

Proper force transfer between reinforcement and surrounding concrete is one of the most significant factors affecting the structural performance of reinforced concrete. Because of the increasing interest in using fly ash and recycled concrete aggregate (RCA) in structural applications, it is necessary to investigate bond properties of mixtures proportioned with high volume of these materials. The present study investigates bond strength between concrete and reinforcing steel in full-scale beams constructed with various "green" concrete mixtures, including high-volume fly ash concrete containing 50% Class C fly ash replacement (FA50), concrete with 50% of coarse RCA replacement (RCA50), as well as a so-called "sustainable concrete" (SC) proportioned with 50% Class C fly ash and 50% RCA. Conventional concrete (CC) made without any fly ash and RCA is employed as the Reference mixture. Data obtained from the testing of 11 full-scale spliced beams are analyzed, including one beam per concrete type (except for RCA50) for investigating the top-bar effect. Experimental results are compared to six different analytical models available in literature. Results are also evaluated based on the bond database of specimens fabricated with RCA developed through literature survey as well as the database proposed by ACI Committee 408 for bond in CC. On average, SC specimens exhibited 15% higher normalized bond strength compared to the Reference beams. Performance of SC mixture was similar to that of RCA50, which were both slightly (6%) lower than that of the FA50 beams in terms of bond strength. No sign of top-bar effect was observed for the FA50 and SC beams. [ABSTRACT FROM AUTHOR]

There is a demand for flowing concrete (FC) in concrete structures that are inaccessible and have congested reinforcement. Although mixture proportioning methods are available for conventional concrete (slump < 7 in. [178 mm]) and for self-consolidating concrete (very high slump values and high flow), until recently, a rational method for proportioning FC has not been available. There is a knowledge gap for proportioning FC mixtures (slump > 7.5 in. [190 mm]). The mixture proportioning method presented herein involves quantitatively assessing the coarse aggregate (CA) shape and packability along with the combined aggregate void (AV) content to proportion FC mixtures. The aggregate characteristics can be used to determine the fine aggregate (FA)-to-CA ratio (FA/CA) that results in a minimum aggregate void content. Using this minimum void content and the aggregate characteristics, the paste volume for flowable concrete trial mixtures can be estimated. This research determined that the past volumen (PV)-to-AV ratio (PV/AV) significantly influences the slump flow and VSI (stability) but does not significantly influence the J-ring passing ability for the mixtures assessed in this research. Results indicate that FC mixtures with adequate flowability, stability, and passing ability can be proportioned using this method. [ABSTRACT FROM AUTHOR]