Eco-Efficient Lightweight Foam Concrete: Synergistic Effects of White Cement and Oriental Clay on Mechanical Performance and CO₂ Reduction

Abstract

The main objective of this study is to develop an innovative lightweight foam concrete with a target dry density below 500 kg/m³, combining satisfactory mechanical performance with a reduced carbon footprint as a sustainable alternative to conventional construction materials. Considering the wide range of applications of foam concrete, this research focuses on its use as a thermal insulation material for building roofs, where low density, adequate mechanical strength, and improved environmental performance are essential. The experimental program first investigated a reference mixture produced with 100% White Cement CPJ 55, followed by mixtures in which the cement was partially replaced with locally sourced oriental clay at substitution levels ranging from 10% to 20% by cement mass. The physical and mechanical properties of the developed mixtures were evaluated through a comprehensive experimental campaign, including density measurements and compressive strength tests at different curing ages. The results demonstrated that replacing 20% of White Cement CPJ 55 with oriental clay enhanced the 28-day compressive strength by approximately 30% compared with the reference mixture while simultaneously reducing CO₂ emissions by about 20%. To better understand the microstructural mechanisms responsible for these improvements and optimize the proposed formulation, selected specimens were characterized using scanning electron microscopy (SEM). The observations revealed that the incorporation of oriental clay promotes a denser cementitious matrix and a more homogeneous pore structure, contributing to the improved mechanical behavior. Overall, the findings confirm the feasibility of producing eco-efficient lightweight foam concrete using locally available materials, providing a promising solution for energy-efficient and low-carbon building applications.