Performance of subgrade soil stabilised with by-product recycled mill scale and cementitous materials

In Jordan, three major steel-manufacturing factories dump their by-product, recycled steel, randomly in open areas creating environmental hazards. This study intended to evaluate the effectiveness of using a By-product Recycled mill Scale (BRS) in improving the geotechnical properties of high-plastic subgrade soil. The efficacy of the BRS was judged by the improvement in the consistency limits, compaction, free swell, Unconfined Compression Strength (UCS), and the California bearing ratio (CBR). Results showed that BRS additives reduced the plasticity index and the free swell, increased the UCS, the maximum dry density, and the CBR values. Cementitious materials (lime and cement) were added to the subgrade soil that was stabilised with 20% BRS for pavement's subbase applications. Resilient modulus (MR) was performed using Repeated Load Triaxial (RLT) device to evaluate the resilient response of laboratory-moulded stabilised specimens under cyclic loading. The results showed that the cement-BRS-stabilised soil specimens showed the highest improvement. As a conclusion, BRS showed a positive effect on the geotechnical properties of the soil and it can be used as an additive to improve the geotechnical properties of the subgrade soil and thence solve the BRS disposal problem.