Effects of Tuff Powder on the Hydration Properties of Cement-Based Materials under High Temperature

In some instances, traditional mineral admixtures, such as fly ash and slag, have been insufficient, and tuff powder (TP) has been used as an alternate replacement. However, the mechanisms of the hydration of tuff powder have rarely been studied, which has restricted its application; therefore, this paper studied the hydration mechanisms of a cement–TP composite under different temperatures. In this study, the influence of TP on the hydration properties of cement-based materials under different curing temperatures was investigated by a compressive strength test, X-ray diffraction (XRD), and thermogravimetric and differential thermal analysis (TG–DTA). Our results showed that a high curing temperature effectively promoted the hydration of Portland cement and the pozzolanic reaction degree of TP and improved the mechanical and microstructural properties of cement-based materials. The high temperature was most conducive to the early development of strength. Additionally, different water-to-binder ratios showed different effects on the contribution coefficients of high curing temperatures. The effects of a high temperature on the pozzolanic reaction of TP may lead to greater Ca(OH) 2 consumption during hydration. This research provides a new way to improve the reaction activity of TP and lays a theoretical foundation for applying TP to precast concrete products, mass concrete, or concrete construction in hot seasons.