Prediction of mechanical properties of lightweight basalt fiber reinforced concrete containing silica fume and fly ash: Experimental and numerical assessment

As a building material, concrete has its own advantages and disadvantages. One of the weaknesses of concrete is its very low tensile strength and strain as well as brittleness under flexural or compressive loading, which results in sudden failure of the concrete structures during earthquakes. On the other hand, low strength of lightweight aggregates and their fragility lead to poor performance of the lightweight concrete against ductility. Therefore, this study investigated mechanical properties of the lightweight structural concrete containing expanded clay aggregate and different amounts of basalt fibers (0-0.5%). Hence, pozzolanic materials of silica fume and fly ash were used to modify some of the concrete properties in lightweight concrete mixtures as a substitute of part of the cement weight. In total, 21 mix designs were made and their fresh and hardened properties were tested at different ages of 7, 28, and 90 days. Results indicated that the presence of basalt fibers reduced slump and compressive strength by 37% and 13%, respectively. It was also found that all mixtures had a "good" level of water absorption quality and thus were placed in the category of "structural concrete". Results also indicated that addition of fibers improved tensile, flexural strength, and shrinkage. In order to predict empirical results, an adaptive neuro-fuzzy inference system (ANFIS) was used as a reliable method for evaluating and estimating the results and numerical analysis outputs showed accurate estimation of the empirical results.