Effects of binder and CaCl2 contents on the strength of calcium carbide residue-fly ash concrete

This paper presents a concrete that utilizes a calcium carbide residue and fly ash mixture as the concrete binder instead of Portland cement. The ground calcium carbide residue (CR) was mixed with classified fly ash (FA) at a ratio of 30:70 (CR:FA) by weight and used as a binder to cast CR-FA concrete specimens. The effects of binder content, water to binder (W/B) ratio, and CaCl2 dosages on the compressive strength of CR-FA concrete were evaluated. In addition, the modulus of elasticity of CR-FA concrete was measured. The results indicated that the CR-FA mixture could be used as a cementitious material for concrete without using Portland cement. Increasing the binder content and reducing the W/B ratio improved the compressive strength of CR-FA concrete, similar to normal concrete. The addition of 3% CaCl2 by weight of binder yielded CR-FA concrete that exhibited high workability and accelerated the compressive strength at early ages. In particular, the 450 kg/m3 of CR-FA binder content with 3% CaCl2 at a W/B of 0.35 yielded a compressive strength as high as 24.3 MPa at 90 days, even though this concrete did not contain Portland cement.