Using waste plastic materials to improve the granular soil bearing capacity

Soil reinforcing is one of soil improvement methods by using of reinforcing materials (with suitable performance in tension) in soil (with fairly compressive strength and weakness in tension). In recent years, numerous studies have been carried out about the application of reinforced soil and bearing capacity of granular soils. Generally, these studies are limited to reinforced embankment with geosynthetics and steel stripes and even plastic parts. So using of plastic waste to improve the bearing capacity of embankment has not been considered. Therefore, in this research the effect of plastic wastes to improve the bearing capacity of granular soils has been investigated. The variables considered are using one type of disposal plastic wastes in different weight percentages at irregular (random) reinforcement and regular reinforcement (with specified layers) in granular embankment. The research was carried out in small laboratory scale using CBR tests. According to results, placing plastic waste parts in sandy soil increases the bearing capacity remarkably. The optimum values were obtained at 2% to 2.5% plastic weight ratios to soil weight. Also the required energy conditions to attain optimum percentage were investigated. In this regard, the strain-stress behavior of soil was studied. The results show that increasing of plastic parts to 2%-2.5% at irregular and regular condition, respectively, raises the soil elasticity coefficient to 234 and 152% respectively.