Influence of sand type on acid resistance and capillary absorption capacity

This study aims to investigate the effect of binary and ternary combinations of river sand (RS), crushed sand (CS) and dune sand (DS) on the physical and mechanical performance of concrete subjected to acidic curing environments. The RS was replaced by CS and DS in different mass proportions. The five concrete mixtures M21(RS), M04(0.6CS + 0.4DS), M10(0.2RS + 0.6CS + 0.2DS), M15(0.4RS + 0.6CS) and M16(0.6RS + 0.4DS) were prepared. The sorptivity was evaluated by measuring the sorptivity coefficient (S, cm*s-0.5) after 28 days of submersion in distilled water. Concrete specimens were submersed in distilled water, 5% sulfuric acid (H2SO4), and 5% hydrochloric acid (HCl) for up to 180 days in order to test their acid resistance. Visual inspection, changes in mass and changes in compressive strength were used to evaluate the specimens' resistance to acid attack. The results indicated that replacing RS with CS led to an increase in sorptivity, while replacing RS with DS resulted in a decrease. When both CS and DS were used in place of RS, acid resistance in 5% HCl solution decreased. In 5% H2SO4 solution, substituting RS with CS reduced mass loss, but replacing RS with both CS and DS weakened the concrete's compressive strength.