Assessment of Lime Stabilized Soils Modified with Egg Shell Ash for Road Construction

Abstract

The need to have in-depth knowledge about the Engineering properties of soil and the sub-soil condition for road construction especially in the southwestern Nigeria brought about this study. Some strength properties (California Bearing Ratio (CBR), Compaction, Unconfined Compressive Strength (UCS), and direct Shear tests) of lime stabilized soils modified with Egg Shell Ash (ESA) were assessed. Soil samples were obtained from each state in the study area and transported to the laboratory, where they were stabilized with 6% lime and 0 to 10% ESA before the above-mentioned tests was conducted on them. The local additive was also subjected to a chemical analysis. Results showed that ESA additive has low SiO2 and high CaO compounds. Increase in ESA resulted in increase of all the strength properties (Maximum Dry Density (MDD), CBR, UCS, Cohesion (C), Shear strength (S) and Angle of Internal Friction (ϕ)) and reached peak at 8% ESA, thereafter decrease; albeit, Optimum Moisture Content (OMC) decreases. After the improvement process, almost all the unsuitable soil samples became suitable for use as pavement layer materials. Consequently, a blend of 6% lime and 8% ESA content is recommended for soil improvement, especially for road pavement layers in southwestern Nigeria.