Combined Effects Of Eggshell Powder And Hydrated Lime On The Properties Of Expansive Soils

Reem Alqaisi, Thang M Le and Hadi Khabbaz

This study involves the utilization of eggshell powder (ESP) as a supplementary additive to lime stabilization of expansive soil and evaluates its potential in enhancing the performance of expansive soil treated with lime. Eggshell is a waste material obtained from several sources. Some of the challenges associated with dumping eggshell are odour, insect growth, disposal costs and availability of disposal sites. In order to reduce these environmental issues, eggshells can be processed into ESP and play a role as a soil stabilizing agent. Calcium oxide is considered to be the main ingredient of the ESP. Therefore, an experimental program is carried out to test a mixture of kaolinite, bentonite and Sydney fine sand, which is simulated to be as an artificial expansive soil. The eggshell powder was used as an additive to 5% lime in four percentages of 5%, 10%, 15% and 20% by total dry weight of the soil mass. Results of linear shrinkage, proctor compaction, and unconfined compressive strength tests after various curing time are presented in detail and compared with untreated soil samples. The outcomes of these experimental investigations indicated that the combination of eggshell powder and hydrated lime led to a further decrease in linear shrinkage and the maximum dry density of expansive soil samples. It was found that the improved geotechnical characteristics were more pronounced for 5% ESP treated expansive soil. At this percentage, the compressive strength at failure and the corresponding strain increased slightly by 18% and 9%, respectively, compared to the untreated expansive soil after 28 days of curing. Moreover, in comparison with lime (5%) only stabilized expansive soil, the combined lime (5%) and ESP (5%), induced approximately 15% build-up in the compressive strength of samples. Based on the reasonable laboratory test results, this addition is recommended to improve the shrinkage properties and stabilize the expansive soils where the high performance of subgrade is neglected.