The influence of eggshell nanoparticles as a partial replacement of cement in concrete

Eggshell waste is considered one of the widely disposed materials that need to be utilized sustainably. At the same time, rising cement manufacturing leads to an increase in the emission of CO2, which is a serious environmental issue. Therefore, this work investigated the use of novel eggshell nanoparticles as a partial replacement material for Portland cement for these two issues. This study involves investigating the effect of inserting eggshell nanoparticles in various ratios (0, 5, 10, and 15%) as a concrete ingredient with various initial water content to cement (w/c) (0.2, 0.4, and 0.6) and immersed in water for 7 and 28 days on the workability, strength, and corrosion of the specimens. The prepared specimens were inspected by compressive, flexural, and tensile strength tests. In addition, the impact of adding eggshell on the capability of the concrete mixture to withstand severe situations was investigated by Rapid Chloride Ion Penetration and slump tests. The most significant finding of this investigation is confirming that adding eggshell nanoparticles increases the compressive, flexural, and tensile strengths. A contrary effect was observed to raise the w/c ratio, which is attributed to the obverse effect of the water ratio to eggshell on the concrete's porosity. The significance of strength improvement by adding eggshell nanoparticles was confirmed by statistical analysis.