The use of oil shale fly ash to improve the properties of Irbid soil

Purpose: The purpose of this paper is to evaluate the possible use of oil shale as a soil stabilizing agent for expansive soils. Design/methodology/approach: An experimental work has been fulfilled to investigate the influence of oil shale ash (OSA) on the geotechnical behavior of the expansive soil of Irbid, Jordan. Three swelling-shrinkage soils were considered in this study along with various percentages of OSA varying at 2, 4, 6, 8, 10 and 12 per cent by dry weight of the soil. A series of laboratory tests were conducted on the soil samples before and after mixing it with OSA. These tests were soil classification, Atterberg limits, compaction test, falling head permeability test, unconfined compression test, free swelling, swelling pressure and California bearing ratio (CBR) test. Findings: Laboratory tests results indicated that OSA is effective in improving the texture and strength of the treated soil by reducing plasticity index, swelling potential and swelling pressure and moderately enhancing soil strength properties including the unconfined compressive strength (q_u), maximum dry unit weight (γ_d-max.) and CBR test. Originality/value: OSA showed potential as a low-cost soil stabilizing agent for swell-shrink soils.