Development of environment-friendly engineering composite materials utilizing Pisha sandstone and solid waste under different curing conditions

Producing low-carbon clinker-free engineering material is beneficial to environmental protection and energy conservation. This paper reports the utilization of natural Pisha sandstone (PS) as a new precursor to manufacture an environment-friendly engineering composite material in combination with solid waste (BFS, FA, and SF). The curing conditions of PSCM have been reported to a limited extent in a few studies. In this study, special attention was given to the mechanical properties and hydration progress of three different Pisha sandstone composite materials (PSCM) under different curing conditions. The prepared samples were subjected to different heat-curing temperatures (20 ℃, 40 ℃,60 ℃, and 80℃) for 24 h, different water curing time (1 day, 21 day, and 27 day), and aging effect (7-14-28-90 days). The results indicated that solid waste addition significantly increased the compressive strength under all curing conditions. However, high-temperature cure facilitated samples gained much of strength with less curing duration, whereas high-temperature caused shrinkage cracks at later age, which was detrimental to strength development. The satisfactory compressive strength was obtained under the combination of heating and water curing (80 ℃ for 24 h followed by water curing for 24 h) and especially containing 10% SF (22.38 MPa). The mineral crystallographic characterization and microstructure revealed that the development of strength depends on the amount of hydration products and high-temperature cure favors the formation of gels.