International Concrete Abstracts Portal

This investigation aims to study the effect of different types and volumes of synthetic fibers (SFs) on the cyclic behavior of rubberized beam-column joints. Different self-consolidating rubberized concrete (SCRC) mixtures with different percentages of crumb rubber (CR) and SFs were tested. The main parameters were the percentage of CR (0, 15, and 25% by volume of sand), coarse aggregate size (10 and 20 mm [0.39 and 0.79 in.]), concrete type (SCRC and vibrated rubberized concrete), type of SF (microsynthetic fibers [MISFs] and macro-synthetic fibers [MASFs]), length of SFs (19, 27, 38, 50, and 54 mm [0.75, 1.06, 1.5, 1.97, and 2.13 in.]), and volume of SFs in the mixture (0, 0.2, and 1%). The structural performance of the tested beam-column joints was assessed based on load-deflection response, initial stiffness, load-carrying capacity, first cracking load, cracking behavior, failure mode, rate of stiffness degradation, displacement ductility, brittleness index, and energy dissipation. The results indicated that using MISFs slightly improved the structural performance of beam-column joints, while using MASFs had a significant effect on enhancing the load-carrying capacity, ductility, stiffness, and energy dissipation of tested joints. The highest improvement in the cyclic performance of beam-column joints was noticed when 38 mm (1.5 in.) MASFs were used. The results also showed that adding a high percentage of SFs (1%) to joints with a high percentage of CR (25%) compensated for the reduced load-carrying capacity caused by the high percentage of CR and helped to develop the joint with significant improvements in ductility, cracking behavior, brittleness index, first crack load, and energy dissipation.

The purpose of this paper is to study the mechanical behavior of concrete blocks and prisms when performing axial compression tests within the Brazilian base of knowledge, intending to foment data of this kind for a world-based network. The blocks were built using five different mixtures in which the quantity of cement and the compacting ratio (density) were varied (during the fabrication process). The three-course-high prisms were assembled using 1 cm (0.39 in.) thick full-bedded joints, always trying to leave the mortar’s characteristics constant. The axial compression tests were conducted according to Brazilian practice code recommendations, because most of these standards are very similar to international practice codes. The compressive strength, strains, and rupture form of each mixture studied were recorded. Attempts were made to correlate the strength, efficiency ratio (block strength/ prism strength) of the prisms, strains, and rupture form; with the quantity of cement and compacting ratio. The data are presented in tables and figures, and the obtained results are discussed throughout the text.