In this study, the effect of polypropylene and nanosilica fibers on the physical and mechanical properties of sandy soils such as optimum moisture and maximum dry density as well as mechanical properties such as CBR and soil shear strength have been investigated. The results of this research can be used for road paving engineers and geotechnical engineers to strengthen and improve the soil.
From the studied sandy soil, with different percentages of polypropylene and nanosilica fibers, the required number of laboratory samples were prepared for statistical studies. In addition to graph analysis and trend analysis of parameters from graphs, microscopic properties of stabilized soil were also analyzed using XRD and SEM. With the addition of polypropylene fibers, there was a significant increase in the CBR content of soil samples, the highest of which, CBR, increased by 58%. There was no significant difference between the load ratio of the sample containing 6 and 12 mm fibers, but the load ratio of 12 mm polypropylene fibers was slightly more than 6 mm. At weight percentages less than 1%, the distance between polypropylene fibers is large and there is no integrated mass of soil and fibers, so the optimal amount of polypropylene fibers is 12 mm long and for different weight percentages (0.1, 0.5, 1) Occurs with 1% polypropylene fibers and maximum resistance is achieved. The reason for this increase in resistance is the random distribution of individual filaments in the soil.
The reinforced soil also acts as an integral part, and this integrated function of the soil and the fibers causes the soil grains to lock between the fibers. California bearing ratio increased by adding different percentages (1, 2, 3) of nanosilica to the soil so that the highest increase was related to nanosilica 3%.
The highest bearing ratio and shear strength for different percentages of polypropylene fibers (0.1, 0.5, 1) with nanosilica (1, 2, 3) are related to the mixing of 1% polypropylene fibe