Effect of tuff powder on the performance of low heat Portland cement-based materials

Abstract

Low heat Portland cement (LHPC), a low-carbon cement variant, finds extensive application in expansive water conservancy ventures. To amplify energy efficiency and curtail CO2 emissions, supplementary cementitious materials (SCMs) are frequently harnessed as cement substitutes. This research delves into the impact of tuff powder (TP) on LHPC mortar traits via an array of evaluations encompassing rheological scrutiny, compressive strength assessment, isothermal calorimetry, X-ray diffraction (XRD), thermogravimetric analysis (TG), mercury injection porosimetry (MIP), and scanning electron microscopy (SEM). Notably, the research divulges that TP incorporation heightens yield stress and plastic viscosity within LHPC paste, concurrently expediting the hydration process and mitigating the maximum heat rate. Over a 90d span, TP efficiently increase of binding water content due to the pozzolanic reaction of TP and Ca(OH)2. Compared with FA, the addition TP can significantly enhance the 7d compressive strength of LHPC up to 39%. Augmented TP content engenders a more intricate and fine-pored structure in LHPC paste, bolstering cement paste density. Importantly, TP incorporation contributes to diminished energy consumption, lowered CO2 emissions, and amplified sustainability. In order to optimize material properties, the content of TP must be strictly controlled in the range of 20%-40%.