Feasibility study on utilization of pulverized eggshell waste as an alternative to limestone in raw materials for Portland cement clinker production

Abstract

In the Portland cement industry, the reuse of industrial by-products as raw materials for cement clinker production has been increasing. Eggshell waste, which is discharged in large volumes by households and the food industry, consists of a trigonal-calcite (CaCO3) structure, and it possesses characteristics analogous to limestone. In this study, eggshell cement (ESC) was synthesized at 1470 °C using pulverized eggshell waste as a raw material for cement clinker production, as an alternative to limestone. Limestone cement (LPC) clinker was also produced under identical conditions to ESC. The anhydrous phases in the synthesized cements and hydrated cement pastes were characterized using X-ray diffraction with Rietveld refinement, field emission scanning electron microscopy, isothermal calorimetry, compressive strength tests, and thermogravimetry analysis. The results indicated that ESC exhibited four main cement clinker phases, namely C3S, C2S, C3A, and C4AF, identical to commercial ordinary Portland cement (OPC). Moreover, the strength development and hydration characteristics of ESCs are similar to those of LPC. As a consequence, this study illustrated that recycling eggshell waste to partially substitute limestone in raw materials for OPC production is feasible.