Strength Improvement and Crack Mitigation in Clay Soil Using BasTalt Fiber and Pozzolanic Additives

Abstract

Desiccation cracking is a phenomenon usually associated with cohesive soils, starting at their surface and then spreading deeper. In such soils, the formation of cracks during desiccation is a natural phenomenon. The lifetime of geo-infrastructures, especially those used as hydraulic barriers, can be greatly extended by reducing desiccation-induced cracking. Improving soil properties through the utilisation of additives is an effective way to reduce the occurrence and impacts of desiccation cracks. In this study, the effect of basalt fiber and different pozzolanic additives (lime, fly ash and silica fume) on the desiccation cracking behavior and unconfined compressive strength of a high plasticity clay was investigated. Unconfined compressive and desiccation cracking tests were carried out at different additive contents. Also, the effect of wetting-drying cycles on desiccation cracking behavior was determined. The used additives provided a significant increase in the unconfined compressive strength of the clay soil. The additives were effective in reducing the amount of desiccation cracks in the clay soil. As a result of the tests, wide and deep cracks occurred on the surface of natural clay soil samples during desiccation. When lime was added to the clay soil, the crack area decreased. It was determined that the cracks continued to decrease when fly ash or silica fume was added together with lime. Smaller and superficial cracks were formed with the addition of lime + silica fume, lime + fly ash and basalt fiber to the clay soil. In particular, it was observed that the cracks decreased to negligible levels with the addition of basalt fiber and silica fume. The results showed that the additives can serve as an effective solution in preventing desiccation cracks in clay soils.