The Study of Clinoptilolite Effect on the Strength Parameters of Clayey Sand Soil Considering Soil Failure Behavior

Improvement of soils with the additives is one of the methods for surface or deep soil treatment. Improvement of soil by additives is one of the most important issues in geotechnical engineering. Typical additives such as cement, lime, fly ash and some nano materials have been previously investigated but pozzolanic materials, especially zeolite, which have unique features, have been less considered in geotechnical engineering. Due to the lack of sufficient studies on the effect of zeolite on soil properties and chemical properties of these materials, this study examines the effects of zeolite on soil strength parameters. In this paper, the effect of a type of zeolite called Clinoptilolite on the strength parameters of clayey sand soil has been studied. For this purpose, after conducting the identification tests on clayey sand (a mixture of clay and 161 Firoozkooh sand), the Atterberg limit test was performed on natural and stabilized samples with 5, 15 and 25\% Clinoptilolite. Also, uniaxial compressive strength test was taken into on samples with 0, 5, 10, 15, 20 and 25\% additive and curing times of 7, 14 and 28 days. The results showed that the atterberg limit increased with increasing the percentage of Clinoptilolite. Furthermore, the uniaxial compressive strength of the soil increased with increasing the amount of Clinoptilolite and curing times. The highest strength occurred at 25\% additive and 28 days. The failure behavior of the samples showed that with increasing time and percentage of the additive brittle failure was occurred and after brittle fracture the uniaxial strength decreases with high speed. Also, with increasing curing time, the failure plan in the samples becomes clearer. The results of this research are based on the laboratory test on a clayey sand soil with the engineering specifications presented in the study and may be different for other soils of this type. These results are also laboratory tests and may have a significant difference in soil conditions.