Evaluating the Integration of Bio-based Waste into Cement Production: A Pathway to Sustainable Building

Abstract

Rapid urbanization has increased the demand for building materials, depleting naturalresources used in cement production and prompting the use of alternative and waste materials.This research verifies that eggshell powder waste can fully replace limestone in clinkersynthesis. Five clinkers were produced using eggshell powder, aluminum sources (bentonite,zeolite, fly ash, and kaolinitic–illitic clay), Fe-slag, and quartz sand, with mechanicalpreprocessing (10–30 min) before sintering at 1300 ◦C. Experimental tests assessed theeffects of mix design and mechanical activation on clinkerization, phase formation, temperature,and mechanical properties. XRD, FTIR, and SEM/EDS confirmed consistent phasecompositions and primary cement minerals. Aluminum source raw materials contributedsignificantly to tricalcium aluminate and tetracalcium aluminoferrite formation. Eggshelland fly ash promoted tricalcium silicate and dicalcium silicate synthesis, enhancing cementstrength at early and late ages. Longer mechanical pretreatments hindered clinkerization.Eggshell-based cements untreated or pretreated for 10 min are suitable for structuralconcrete; 20–30 min pretreatment is appropriate for low-demand or non-structural applications.The proposed methodology reduces clinker manufacturing temperature by about100 ◦C from the typical range of 1400–1450 ◦C while maintaining mechanical propertiescomparable to ordinary Portland cement