Eggshell Powder from Moroccan Sources: A Promising Partial Replacement for Cement in Eco-Friendly Concrete

The cement industry is one of the largest contributors to global CO2 emissions, accounting for approximately 7–8% of total emissions due to its energy-intensive production process and heavy reliance on clinker. In response to increasing environmental concerns, the development of low-carbon construction materials has become a major research focus. Simultaneously, the food industry generates vast quantities of eggshell waste, estimated at over 70 million tons globally per year. In Morocco, eggshells are commonly discarded in household or food processing waste streams, causing environmental issues due to their slow biodegradation and potential for microbial growth. However, eggshells are composed of more than 90% calcium carbonate (CaCO3), giving them chemical similarity to limestone, a key component in cement. This study investigates the feasibility of using locally sourced, ground, non-calcined Moroccan Eggshell Powder (ESP) as a Supplementary Cementitious Material (SCM) to partially replace Portland cement in mortar formulations. ESP was incorporated at replacement levels of 10%, 15%, 20%, and 30% by weight. The impact of ESP on physical properties such as water absorption, bulk density, and workability was assessed using standard procedures, including the Abrams cone method. Thermal conductivity was measured using the Hot Disk method. Compressive strength was evaluated at 7 and 90 days of curing. The findings demonstrate that ESP can reduce cement demand, valorize biogenic waste, and enhance the sustainability of construction materials, with performance influenced by the replacement percentage.