Enhancing Environmental Sustainability of Calcium Aluminate Cement: Sustainable Efflorescence Mitigation Through Diatomite-Mediated Dual Pore-Chemical Regulation

This study investigates the eco-friendly efflorescence inhibition mechanism of natural diatomite in calcium aluminate cement (CAC) mortars through multi-scale analyses. Optical microscopy and SEM revealed that diatomite incorporation reduced visible efflorescence by transforming surface deposits (CaCO3 and AFt phases) into submicron-sized microcrystalline or amorphous forms (< 100 μm). Capillary water absorption tests demonstrated a significant 45% reduction in water uptake with 30% diatomite, linked to pore structure refinement and enhanced impermeability, thereby reducing long-term deterioration risks. PH analysis showed a decrease, destabilizing AFt and suppressing CaCO3 crystallization. Synergistic mechanisms included chemical neutralization (SiO2 reacting with Ca(OH)2 to form C-S-H gel), pore filling (blocking capillary channels), and ion adsorption (hydroxyl groups trapping Ca2+/Na+, reducing ion leaching). These effects collectively reduced ion migration and alkaline dissolution, correlating with a 50% decrease in efflorescence area. The findings highlight diatomite’s dual role in pore optimization and pH regulation, offering a sustainable and resource-efficient strategy for enhancing the long-term durability, service life, and aesthetic longevity of CAC-based systems, contributing to reduced environmental impact through minimized maintenance and material replacement needs.