Milad Tofighkhah - Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran.
Neda Hashemidanesh - Civil Engineering Department, University of Mohaghegh Ardabili, Ardabil, Iran.
Mahmoud Ameri - Department of Civil Engineering, Iran University Since and Technology, Tehran, Iran.

Resistive subsoil is a basic construction necessity in civil works because it is the foundation of a structure that distributes the loads effectively, and the structure will settle and crack under the applied loads if the soil is not strong enough. In many cases, the existing natural soil cannot fully support the desired structure and needs to be improved for its resistance properties. Soil stabilization methods are: ۱) mechanical, ۲) chemical and ۳) physical , and this study tries to examine how the combined carbon fibers-nanosilica, as a new stabilizer, improves the mechanical characteristics of the soil by studying the effects of nano-silica and recycled polyester fibers on the engineering features of the clayey sand soil, especially the shear and unconfined compressive strengths. To this end, two different-ratio soil-fiber and soil-nano silica combinations, ranging, respectively, between ۰ and ۰.۶% and ۰ and ۱% were used, and the results showed that adding the mentioned stabilizers increased the soil strength.

Clayey Sand Soil, nano-silica, Carbon Fibers