Mechanical Properties and Drying Shrinkage of Alkali-Activated Coal Gangue Concrete

Abstract

The feasibility of composite-activated coal gangue (CACG) as the primary cementitious material for concrete was experimentally studied in this paper. The effects of concrete strength grade on slump and slump flow, compressive strength, splitting tensile strength, axial compressive strength, elastic modulus, and drying shrinkage of alkali-activated coal gangue concrete (AACGC) were experimentally investigated. Experimental results indicated that the slump and slump flow of the AACGC were smaller than that of ordinary Portland cement concrete (OPCC). The mechanical properties of the AACGC were superior to those of the OPCC. The compressive strength, splitting tensile strength, axial compressive strength, and elastic modulus of the AACGC were 1.17 times, 1.04 times, 1.47 times, and 1.04 times those of the OPCC, respectively. With the increase in concrete strength grade, the mechanical properties of the AACGC have gradually increased. The difference in failure modes of axial compressive strength between the AACGC and OPCC was analyzed. Moreover, the empirical formulas of the elastic modulus and compressive strength for the OPCC in various regions codes were summarized, and found that the empirical formula in GB 50010-2002 code and EN 1922 Eurocode 2 was also applicable to the AACGC. Finally, the mass-loss rate and drying shrinkage for the AACGC at different concrete strength grades were systematically analyzed, and a hyperbolic prediction model was proposed to reflect the drying shrinkage behavior of the AACGC.