Geotechnical Improvement of Subgrade Soil Using Quicklime

Abstract

This research investigates the effect of quicklime addition on improving the geotechnical properties of clayey soil collected from the Al-Haffah area in Latakia Governorate and evaluates its suitability for road subgrade applications. Soil samples were treated with different quicklime contents of 4%, 6%, 9%, and 12% by dry soil weight and cured for 7, 14, and 28 days. Laboratory tests included Atterberg limits, Standard Proctor compaction, unconfined compressive strength (UCS), direct shear, and California Bearing Ratio (CBR) tests.

The results showed a significant reduction in the plasticity index with increasing lime content, indicating improved soil workability. In addition, UCS and CBR values increased, reflecting enhanced soil strength and bearing capacity. The optimum moisture content increased, while the maximum dry density decreased after stabilization. Shear strength characteristics also improved with lime treatment.

The findings confirm that quicklime is an effective and economical stabilizing agent for clayey soils in coastal regions, reducing the need for soil replacement and supporting sustainable road construction through the use of local materials.