Mechanical Properties and Stress–Strain Constitutive Relations of Coal-Fired Slag Concrete

In this study, we conducted a single-factor experiment where fine aggregates in each mixture were replaced with coal-fired slag at replacement rates in the range of 0–100%. We investigated the effect of slag substitution rate on the cubic compressive strength, splitting tensile strength, axial compressive strength, and static modulus of elasticity of slag concrete. Based on the experimental data, the stress–strain curve of the coal-fired slag concrete was divided into four phases: elastic, elasto-plastic, peak, and decline phases. A stress–strain constitutive equation was established to describe the coal-fired slag concrete. A replacement rate of 50% of the formulated coal-fired slag concrete meets the strength requirements of C60 structural applications, and the cubic compressive strength is the same as that of ordinary concrete. Coal-fired slag can be utilized in large quantities, improving the economic value of coal-fired slag and expanding the scope of application of slag concrete.