Stabilizing Geotechnical Properties of Loess Soil by Mixing Recycled Polyester Fiber and Nano-SiO2

Abstract

The present study investigated the effect of recycled polyester fiber in combination with nano-SiO2 as a new stabilizer for improving the geotechnical properties of the loess soil. In addition, it intended to evaluate the effect of adding recycled polyester fiber and nano-SiO2 on engineering properties of the soil, especially the maximum dry density and shear strength using silty loess with low liquid limit. To this end, three different combinations of fiber and nano-SiO2 ratios were used ranging between 2 and 6% in proportions of 33% and 50% for the total dry weight of the soil. Furthermore, three different combinations of fiber-soil ratios were employed which ranged between 0.5 and 1.5% for the total dry weight of the soil, as well as three different combinations of nano-SiO2 ratios ranging between 2 and 6% for the total dry weight of the soil. The results from the compaction test indicated that the maximum dry density of the stabilized loess decreased while the optimum water content increased by adding recycled polyester and nano-SiO2. Based on the results of the direct shear test, the shear strength improved by increasing the contents of the recycled polyester fiber and nano-SiO2 in the soil mixture. Thus, the addition of recycled polyester and nano-SiO2 improved the strength properties of the loess soil. In order to obtain the maximum increase in shear strength, the optimum content of the recycled polyester fiber and nano-SiO2 was 4% of loess soil dry weight in proportions of 33% and 50% in the mixture.