Enhancement of Gypseous Soil Engineering Properties Through High-Density Polyethylene Polymer Addition: A Comprehensive Experimental Assessment

Abstract

An experimental investigation was conducted to scrutinize the influence of high-density polyethylene (HDPE) polymer on the engineering properties of gypseous soil. Soil samples, possessing 38% gypsum content, were extracted from the Tikrit region, Iraq, and were subsequently subjected to varying HDPE polymer concentrations of 1%, 3%, and 6%. An observed augmentation in the maximum dry density was noted when a minuscule quantity of 1% HDPE polymer was incorporated. However, a subsequent increase in polymer concentration resulted in a discernible decrease in dry density. Examination via the double oedometer test elucidated a significant reduction in collapse potential by 64%, 77.7%, and 83.2% upon addition of 1%, 3%, and 6% HDPE polymer, respectively. Direct shear test outcomes revealed a complex influence of HDPE polymer on soil cohesion. In the dry state, a 1% and 6% HDPE polymer addition led to a cohesion increase by 50% and 16.67%, respectively, whereas a 33.3% decrease was observed at a 3% polymer concentration. Conversely, in the soaked state, cohesion was found to decrease by 50% at 1% and 6% HDPE polymer concentrations, and entirely diminished with a 3% polymer addition. Interestingly, the internal friction angle (ϕ) exhibited an increase in both dry and soaked states with escalating HDPE polymer percentages. A contradictory behavior was noted in the California Bearing Ratio (CBR), which decreased in the dry state but increased in the soaked state with a rise in HDPE polymer ratios. In conclusion, the present study substantiates that the addition of HDPE polymer induces modifications in the engineering behavior of gypseous soil. Further research is encouraged to optimize the HDPE polymer concentration for ground enhancement applications.