Performance of Recycled Plastic Pins for Improving Unsuitable Foundation Soil

Civil engineering infrastructures constructed on unsuitable foundation soil are prone to large deformation and bearing capacity failure. A common and traditional approach employed by the Texas Department of Transportation (TxDOT) is to remove in situ soil and replace it with suitable fill material. However, this method can be time-consuming and expensive. To minimize construction time and cost, the use of recycled plastic pins (RPPs) for ground improvement needs to be evaluated as an effective and sustainable technique. This study aims to evaluate the effectiveness of RPPs in improving unsuitable foundation soils. An extensive field-testing program was conducted on RPP-reinforced soil. In the field, four identical sections were constructed, of which three were reinforced with RPPs of different sizes and spacings, and the fourth was left unreinforced so that it could act as a control. Performance monitoring for all four test sections was conducted using inclinometer and pressure plates for more than 2 years. According to the field monitoring data, the reinforced section settlement was reduced by up to 84%, and RPPs carried 78% of the total load. Therefore, RPPs show promising potential for improving unsuitable foundation soil.