Influence of magnetized water and water/cement ratio on the properties of untreated coal fine aggregates concrete

Abstract This study intends to find solutions to increase the untreated coal fine aggregate (UCFA) content as a replacement of natural fine aggregates (NFA) using magnetized water (MW). 112 concrete mixes are produced and tested. Seven UCFA incorporation ratios are used: 0%, 5%, 10%, 15%, 20%, 25% and 30% in term of weight. Using MW in concrete has a significant effect on both the fresh- and hardened-state properties of concrete. Hence, four water magnetization intensities are used (0, 0.6, 1.2 and 1.8 T). Moreover, four base concrete mixes with water-to-cement ratios (W/C) of 0.35, 0.4, 0.45, and 0.5 are produced, and the slump, compressive, tensile and flexural strengths, modulus of elasticity and electrical resistivity of concrete are evaluated. One sample is selected as a control specimen with no UCFA and with tap water. The results are compared with those from previous models to predict the mechanical properties of concrete, and new models are developed to anticipate the hardened-state performance of concrete when both UCFA and MW are used. The results show that 15% NFA can be replaced with UCFA when 1.2 T MW is used with no reduction in compressive and tensile strengths. Moreover, the proposed models can be employed with high accuracy to estimate the modulus of elasticity, splitting tensile and flexural strengths of UCFA concrete based on the compressive strength when MW at different intensities is used.