Limestone derived eggshell powder as a replacement in Portland cement mortar

•Chicken eggshell waste used as a limestone filler in Portland cement mortar.•A larger than laboratory scale method was used to crush raw eggshells into fine powders.•White and brown eggshells were evaluated for their mechanical performance.•Eggshell based limestone mortars had lower properties compared to natural limestone.

In recent years, a general trend exists to reduce usage of natural resources and re-use waste materials. This work aimed to study the performance of ground white and brown chicken eggshell waste powders as potential replacements of conventional quarried limestone in Portland cement mortars. A processing method to produce large quantities of eggshells was developed. Limestone amounts of 0%, 5%, 10%, 15% and 20% by weight were added as Portland cement replacements. Chemical composition, elevated temperature degradation and eggshell particle morphology were investigated. Compression and flexural strength measurements were carried out on mortar specimens. The results showed eggshells contain mostly calcite with small amounts of organic membrane and matrix. The powdered eggshell particles appeared to have an irregular morphology due to the grinding process utilized. The strength of the mortars were affected by the addition of various limestone materials. In conclusion, white and brown eggshells derived limestone powder were found to have inferior properties compared to natural conventional limestone even with 5 wt.% Portland cement replacements.