Effect of the Addition of Industrial Materials on the Properties of Expansive Soil in the Al-Azraq Area, Jordan

Abstract

This study aims to investigate the stabilization of representative samples of expansive soil in the Al-Azraq area. This is achieved by mixing soil with different proportions of four types of stabilizers: lime, phosphatic clay, cement kiln dust (CKD), and sandstone. The index properties of the base soil have been investigated through various tests. The chemical and mineralogical compositions of materials have been examined. Compaction, California bearing ratio, and unconfined compression tests are used to assess the engineering properties of the stabilized soil. The results revealed that with 5% lime, 10% phosphatic clay, 7.5% CKD, and 10% sandstone, the plasticity index reduced from 60% to 17.2%, 18.47%, 17.52%, and 22.70%, respectively. The maximum dry density increased by adding 5% lime from 1.19 mg/cm3 to 1.58 mg/cm3. The optimum moisture content decreased from 40.1% to 25.1% with the addition of 5% lime. The California bearing ratio increased from 9% to 17.5% with the addition of 7.5% CKD. The unconfined compression strength improved significantly with the addition of all stabilizers due to chemical reactions that resulted in the production of binding compounds. The maximum compressive strengths were after 21 days of adding 5% lime and 7.5% CKD (1800 and 1720 Mpa, respectively). According to the results, the addition of 5% lime and 7.5% CKD is responsible for forming new product-binding materials that improve mechanical strength via the pozzolanic reaction. Reusing by-product materials such as CKD and phosphatic clay as non-traditional soil stabilizers could reduce the amount of these materials destined as waste.