The role of calcium carbide residue in the property evolution of high-volume biomass power plant ash composite cement.

The utilization of biomass power plant ash (BPPA) in cement production offers significant economic and environmental benefits. However, high-volume incorporation of BPPA adversely affects the early and long-term strength of cementitious materials. This study focused on the role of calcium carbide residue (CCR) in modifying the mechanical performance and hydration heat evolution of high-volume BPPA composite cement. A suite of analytical techniques, including X-ray diffraction (XRD), thermogravimetric analysis (TG), Fourier-transform infrared spectroscopy (FTIR), inductively coupled plasma (ICP), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP), was employed to characterize the hydration phase composition and pore evolution of the blended cement. It was demonstrated that CCR incorporation significantly shortened the induction and acceleration periods of hydration and diminished the heat evolution. Furthermore, the addition of 8 %-12 % CCR also enhanced both the early and late flexural and compressive strengths of the composite cement. The improvement was linked to the pozzolanic reaction driven by CCR, which encouraged the release of reactive SiO2 and Al2O3 from BPPA, and ultimately led to the creation of C-S-H gels and ettringite. This resulted in microstructural refinement, which in turn boosted the mechanical performance. The findings provide valuable insights for developing low-carbon cementitious materials.