Study on axial compressive stress-strain relationship of alkali-activated slag lightweight aggregate concrete

Abstract

Alkali slag lightweight aggregate concrete (AAS-LWAC) is a new type of green concrete prepared by alkali excited slag as cementing material and lightweight aggregate as coarse aggregate. It can effectively reduce the amount of Polandite cement and reduce carbon dioxide emission. However, there are no relevant studies on its axial compression constitutive properties. The effects of the type of lightweight aggregate, fiber type, and fiber content on the elastic modulus Ec, peak compressive strain εc, and axial compressive strength fcc of AAS-LWAC were studied in this paper. A suitable AAS-LWAC axial compression constitutive model is proposed. Scanning Electron Microscope (SEM) and Computed Tomography (CT) experiments were carried out to reveal the influence mechanism of the microstructure on the axial compressive properties of AAS-LWAC. The results show that AAS-LWAC with pulverized coal ash ceramsite as coarse aggregate has the highest axial compressive strength and peak compressive strain, and AAS-LWAC with shale ceramsite as coarse aggregate has the highest elastic modulus. Steel fiber can significantly enhance the axial compressive strength and peak compressive strain of AAS-LWAC, and the improvement effect is the best when the volume content of steel fiber is 0.6%. Three kinds of fibers can increase the elastic modulus of AAS-LWAC, and the effect of steel fiber is the most obvious.