Enhancing geotechnical properties of Ulwe soil through waste plastic bottle fibers and nano zinc oxide stabilization

Soil stabilization is a critical aspect of foundation engineering that improves subgrade soils' durability and load-bearing capacity. This study examines the effectiveness of two innovative stabilizing agents—waste plastic bottle fibers and Nano Zinc Oxide (ZnO)—in enhancing the geotechnical properties of Ulwe and Navi Mumbai soils. Waste plastic bottle fibers were added in proportions of 0.25 %, 0.5 %, and 0.75 % by weight with length 3 cm, width 1 mm, and thickness 0.1 mm, while ZnO was incorporated in proportions of 1 %, 2 %, and 3 % by weight of dry soil. Experimental tests such as the Standard Proctor, California Bearing Ratio (CBR), and Unconfined Compressive Strength (UCS) were performed to assess the soil's performance. Wet-dry and freeze-thaw cycle experiments, which mimic field conditions, were used to evaluate durability. According to the results, adding 0.5 % waste plastic bottle fibers increased CBR values by 32 %, while adding 2 % ZnO improved CBR by 25 %. Higher ZnO content, however, increased the soil's optimum moisture content (OMC) while decreasing its maximum dry density (MDD). These results emphasize the suitability of waste plastic bottle fibers and ZnO as cost-effective and environmentally friendly soil stabilizing agents, with significant improvements in CBR values.