Effect of Fibreglass on Shear Strength and Dilation Characteristics of Sand

In recent years, environmental awareness about the improvement of soil and recycling of waste materials are gaining more interest among the soil scientists and geotechnical engineers. Fibreglass is a type of plastic and lightweight material. This study was conducted to investigate the effect of fibreglass reinforcement content on the strength parameters of a typical beach sand. The shear strength of unreinforced sand and reinforced sand are carried out by direct shear box apparatus and California Bearing Ratio, CBR device. Three different contents of fibreglass by dry unit weight and relative density were used in this thesis. The percentage of fibreglass content was 0.5%, 1% and 1.5% by dry weight. Relative density was at three different states, loose, medium dense and dense. In direct shear test, it was observed from the results of the tests that the shear strength of sand was not influenced significantly by fibreglass content. An increase of the fibre content caused a decrease in the peak friction angle and dilation angle. According to the results, addition of the fibreglass reinforcement more than 0.5% by dry unit weight of sand, did not improve the shear strength of sand. In other words, the optimum fibreglass content was 0.5 percent. The CBR value increased with the addition of fibreglass reinforcement. Addition of 0.5% of fiberglass reinforcement caused an increase in both the CBR values and shear strength of the soil. Therefore, fibreglass reinforcement improved the engineering properties of the reinforced sands. Keywords: Sand stabilisation, dilation angle, direct shear box test, plastic fibreglass, shear strength parameters.