Strength Improvement of Black Cotton Soil Using Plastic Bottles and Crushed Glass Wastes

The aim of this study was to improve the strength of black cotton soil for its suitability for road subgrade construction using wastes from plastic bottles and glass waste powders. Currently, nondecomposable wastes from plastic and glasses have become threats to the human health and the environment. This study used the wastes to replace cement, since the cost of cement raised due to energy and raw material to use as stabilizer in weak soil. The glass powder (WGP) and the plastic chips were mixed with the soil sample with a percentage by dry weight of 6%, 12%, 18%, and 24% of WGP and 2%, 4%, 6%, and 8% of plastic chips, respectively. The glass waste can be prepared similar to the soil as the requirement of test standards and plastic wastes was used as reinforcement for the soil-glass-mix; hence, its purpose was geomechanical. Laboratory tests for soil-mix physical properties and strength parameters were conducted. Soil laboratory test results proved that the natural soils were classified to A-7-5 as per the AASHTO Soil Classification System and CH as per the Unified Soil Classification System (USCS). The Unconfined Compressive Strength (UCS) improved from 91.92 kPa to 688.83 kPa, and the California Bearing Ratio (CBR) improved from 2.64 to 17.5. The improvement of subgrade soil properties was increased with increased ratios of powder glass and plastic strips. The result indicated that the two stabilizers were very effective in improving strength parameters and index parameters.