Eco-friendly Stabilization of Dune Sand Using CACW, Silt and Bentonite: Najran University Campus as a Case Study

The aim of this study is to investigate the potential use of dune sand (DS), covering large area of Najran University campus, in local pavement structures. Six different mixtures of DS were prepared, with varying percentages of coarse aggregate crushing waste (CACW) (i.e., 5%, 10%, 15%, 20%, 25%, and 30%), silt (i.e., 10%, 15%, 20%, 25%, 30%, and 35%), and 5% of bentonite. To evaluate the mixtures, a number of experiments were carried out, including Proctor compaction, California Bearing Ratio (CBR), basic compressive strength, and shear strength tests. The results revealed a significant increase in unconfined compressive strength values, which ranged from zero for untreated DS to 190, 310, 510, 900, and 1070 kPa for stabilized mix. Nos. 1 through 5, respectively, followed by a slight reduction to 940 kPa for mix. No. 6. Similarly, the CBR values increased from 8% for DS to a maximum of 142% for mix. No. 5, after which there was a slight decrease to 134% for mix. No. 6. Additionally, the cohesion and angle of internal friction increased from zero kPa and 36° for DS to 17 kPa and 37° for mix. No. 5. These findings underscore the potential of using the stabilizing combination of mix. No. 5 (i.e., 40% DS, 30% silt, 25% CACW, and 5% bentonite) to achieve enhanced shear resistance and improved stability.