Diatomite as a Partial and Sustainable Cement Replacement: Chemical, Mechanical, and Thermal Properties

Abstract

This study investigated the use of Moroccan diatomite in its raw and calcined forms in mortar as a partial replacement for cement to reduce the primary energy consumption in cement production. For this purpose, a thermophysical and mechanical study was carried out. In addition, the energy consumption and global warming potential (GWP) associated with the production of these materials were assessed using a cradle-to-gate life cycle assessment analysis. Several samples were prepared by replacing up to 40% of the cement with diatomite, while maintaining the same sand and water content in the mortar. The study found that diatomite reduced thermal conductivity and diffusivity owing to its high insulating potential. However, calcining diatomite up to 850°C altered the quality of the produced silica, resulting in lower values compared with raw diatomite mortars. The mortars’ compressive and flexural strengths slightly decreased when diatomite was used as a substitute, with reductions of up to 10%. Calcined diatomite mortars demonstrated a higher water absorption capacity than raw diatomite mortars. The study concluded that mortars in which 40% of the cement has been partially replaced by either raw diatomite or calcined diatomite offer the most satisfactory thermal performance, while retaining sufficient mechanical strength to enable them to be classified as construction mortars. Calcined diatomite mortars offer favorable performance compared to raw diatomite, suggesting the potential of calcined diatomite to reduce the environmental impact and improve mortar quality, opening prospects for environment-friendly mortars and cost optimization.