Compressive constitutive behavior of steel fiber reinforced geopolymeric recycled aggregate concrete: Experimental investigation and analytical model

Abstract

With the incorporation of industrial wastes and recycled concrete aggregate (RA), steel fiber reinforced geopolymeric recycled aggregate concrete (SFR-GRAC) can ensure both high performance and environmental benefits simultaneously. As a green concrete, SFR-GRAC is promising for practical engineering applications and its constitutive behavior needs a systematical study. This paper presented an experimental investigation on the stress–strain behavior of SFR-GRAC under uniaxial compression, focusing on the effect of RA substitute rates (25%, 50%, 75% and 100%) and steel fiber (SF) volume fractions (0.5%, 1.0% and 1.5%). The failure pattern, compressive strengths, stress–strain curve and corresponding characteristics, as well as energy absorption capacity were studied. The results show that the addition of SF improves the failure pattern and specimen integrity, as well as the mechanical properties in terms of peak stress, peak strain, elastic modulus and toughness due to the fiber crack-bridging action. The compressive strength and elastic modulus of GRAC are deteriorated with the use of RA, except that the decreases are less pronounced when the RA contents are below 50%. Moreover, the negative impact induced by the inclusion of RA can be alleviated by the addition of SF and the activation of alkali-activator as the rehydration of cement particles in old pastes in RA. Finally, based on a comprehensive analysis of the test results in current study and literature, empirical constitutive relations are established to model the stress–strain responses of SFR-GRAC with various RA and SF contents under axial compression, and model predictions show close agreements with test results.