Resilient Response and Permanent Strain of Subgrade Soil Stabilized with Byproduct Recycled Steel and Cementitious Materials

Abstract

Steel manufacturing factories usually dump byproduct recycled steel randomly in open areas, creating environmental hazards. Using such materials in highway construction could be a solution to the environmental hazards generated from their disposal. A combined method of physical and chemical stabilization was used in this study to investigate the value of using mill scale (MS) and cementitious materials in improving the strength and deformation properties of subgrade soil. The results showed that MS additives effectively reduced plasticity and increased maximum dry unit weight, unconfined compression strength (UCS), and California bearing ratio (CBR). Subgrade soil with 20% MS was treated with cement and lime to obtain a strength value of 1.7 MPa (after 7 days of curing) for subbase application. A repeated load triaxial (RLT) device was used to perform resilient modulus (MR) and permanent deformation tests in order to evaluate the response of laboratory-molded stabilized specimens under cyclic loading in accordance with a standard testing procedure. Study findings are explained through a microstructural analysis that used scanning electron microscopy (SEM) supplied with energy-dispersive X-ray spectroscopy (SEM/EDX). The test results showed that, in addition to solving the MS disposal problem, the use of MS as an additive had a favorable influence on the geotechnical properties of the soil.