The impact of adding dual and triple combinations of quicklime and plastic wastes and palm fibers on the California bearing ratio of fine sand.

Fine sand, widely distributed across arid and semi-arid regions, presents challenges due to its low bearing capacity and susceptibility to deformation. This study investigates the enhancement of the California Bearing Ratio (CBR) value of fine sand through the incorporation of palm fibers, plastic waste, and quicklime. This study investigates the enhancement of the CBR of fine sand using palm fibers, plastic waste, and quicklime. Through two experimental phases, optimal dosages were determined as 5.0% quicklime, 0.75% plastic waste, and 1.0% palm fiber. Single additive treatments yielded CBR improvements of 195%, 125%, and 275%, respectively. Combinations revealed that mixing quicklime with palm fibers decreased enhancement efficiency due to chemical incompatibility. Notably, palm fiber-plastic waste mixtures proved more sustainable. This research offers a cost-effective, eco-friendly solution for improving subgrade conditions with clear quantitative outcomes. The findings underscore the potential of recycling plastic waste by mixing with palm fibers for sustainable improvement of fine sand properties. By reducing plastic pollution and encouraging circular resource usage, the combination of natural palm fibers and recovered plastic waste enhances soil performance and promotes environmental sustainability. Furthermore, this approach is more affordable than traditional soil stabilizing methods, especially in areas where local resources are easily accessible.