71 publications from this institution
Concrete is a brittle material, so it is reinforced with fibers (such as steel, glass and nylon fibers) to improve its ductility. On the other hand, the use of fibers resulting from waste is an interesting issue to avoid the negative impact of these wastes on the environment as well as converting them from useless to other valuable materials. Limited studies addressed the mechanical and structural performance of the locally produced waste rope fibers (WRF) and their reuse in concrete. As a result, the goal of this research is to see how different percentages of WRF (0%, 0.25%, 0.5% and 1% by weight of concrete) affect the workability, mechanical (such as compressive and flexural strength, ultrasonic pulse velocity and bulk density) and structural (such as load deflection, crack width and propagation, and ductility index) properties of concrete. Results indicated that WRF improved the compressive and flexural strength of concrete by up to 22% and 4.3%, respectively. Furthermore, the width of cracks of reinforced concrete beams was considerably reduced and the ductility index of WRF-based beams was 3.07–3.24 compared to 1.45 for fiber-free beams.
The reactive powder concrete (RPC) is one of the special concrete types that characteristics with high cement content which means high production cost and CO2 emissions to the atmosphere. Therefore, to enhance the environment as well as to develop green RPC, alternatives to cement, such as supplementary cementitious materials (SCMs) were used. Limited studies addressed the use of a high volume fraction of SCMs as a binary combination in the production of RPC. Thus, this study aims to replace a high percentage of cement (50%) with binary combinations of silica fume (SF), type F fly ash (FA) and metakaolin (MK). The experimental program included two phases. In phase one, two groups (SF+FA and MK+FA) were cast without steel fibers. Based on group performance in the first phase, one group was chosen to be used with steel fibers in the second phase. The flow rate, compressive and flexural strengths, density, ultrasonic pulse velocity and dynamic modulus of elasticity tests were conducted. The phase one results showed that SF+FA combination mixtures had better performance than MK+FA mixtures thus they were selected to be used in the second phase (with the addition of 1% volumetric fraction micro steel fibers). Results indicated that it is possible to produce sustainable RPC in which the cement can be replaced with 30% SF and 20% FA (the total replacement is 50%) in the presence of 1% steel fibers with a remarkable enhancement in compressive strength and flexural strength reached up to 44% and 10%, respectively.
