Early-age compressive behavior and stress–strain relationship of high -strength SSP-cement mortar

Steel slag powder-cement composite mortar (SSP-cement mortar), a low-carbon building material with industrial solid waste can effectively utilize SSP. However, the low hydration activity of SSP has a significant adverse effect on its early-age behavior. In this study, the early-age compressive behavior and stress–strain relationship of a high-strength SSP-cement mortar at the first curing period of 7 days were comprehensively studied. The mix proportion parameters include the replacement ratio of SSP R_s, cement strength grade f_ce, mesh of SSP ν, and water-binder ratio W/B. The curing temperature was set at T = 20℃ and T = 80℃. The results indicate that: firstly, at T = 20℃ and T = 80℃, the optimal values for cube compressive strength f_cu are 71.2 MPa and 112.4 MPa, respectively, axial compressive strength f_c are 50.1 MPa and 85.4 MPa, respectively. Secondly, with the increase of R_s, the f_c, elastic modulus E_c, and toughness U, showed decreasing trends, the peak strain ε_cp shows an increasing trend. The trends have weakened at T = 80 ℃. With the increase of f_ce and ν, all the indexes (f_c, ε_cp, E_c, and U) show an upward trend. With the increase of W/B, all the indexes show a decreasing trend and are more pronounced at T = 20℃. Finally, an early compressive stress–strain relationship of SSP-cement mortar was established. Based on the given parameters and curing temperatures, a compressive strength prediction model is provided to guide engineering applications.