S.O. Osuji

This study examined the use of Crushed Concrete as a soil stabilizer to enhance the geotechnical properties of weak subgrade soils for road construction projects. The growing volume of construction waste and the environmental issues linked to traditional stabilizers such as cement and lime were key motivations for this research. The soil sample was mixed with varying amounts of CC i.e. at 6%, 12% and 18%. Laboratory tests were conducted and they include sieve analysis, Atterberg limits, compaction and CBR tests. The results were analyzed graphically using Microsoft Excel. The particle-size analysis categorized both the natural soil and the crushed concrete as fine sand to fine gravel. The Atterberg limits indicated that as CC content increased, both the liquid limit and plasticity index decreased, suggesting reduced cohesion and better workability. Compaction results revealed that the maximum dry density (MDD) increased from 1.85 g/cm³ at 0% to 1.92 g/cm³ at 12% CDW, while the optimum moisture content (OMC) decreased from 13.52% to 12.00%, indicating an improvement in compaction efficiency and a reduction in water demand. CBR results also showed significant increases in both soaked and unsoaked values with higher CC concentrations, which met the standards of the Federal Ministry of Works and Housing (FMWH, 2016). In summary, this study found that crushed concrete is a potent and environmentally sustainable soil stabilizer that can significantly strengthen and stabilize weak subgrade soils. It demonstrated that using CC can serve as a viable alternative to conventional stabilizers, reducing construction costs while promoting waste recycling. Further research is recommended to investigate the long-term durability and field performance of CDW- stabilized soils under traffic loads.