Investigation of the behavior of Ahvaz sand soil stabilized with metakaolin

Many improvement methods have been proposed in the world which is one of the most common methods of chemical stabilization using lime or cement, which are not compatible with the environment. Therefore, nowadays, the use of pozzolans and geopolymeric cements instead of Portland cement has attracted the attention of various researchers. In this study, the stabilization of sandy soil in Ahvaz city with the help of metakaolin as an additive has been investigated. In this research, the effect of different amounts of variables such as the percentage of metakaolin, the ratio of sodium silicate to sodium hydroxide, the concentration of sodium hydroxide, and the ratio of alkaline activator solution to the additive at the curing ages of 7 and 28 days have been discussed. Samples are subjected to unconfined uniaxial compressive strength (UCS) evaluation and microstructural investigation, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyzes are used. The results of this research show that in order to achieve optimal resistance, it is necessary to mix 20% metakaolin, the ratio of sodium silicate to sodium hydroxide is 2.5, the concentration of sodium hydroxide is 12 Molar, and the ratio of activator solution to additive is 0.5. The strength of the sample with 28-day curing reaches about 5 MPa, which is about 3 times more than cement samples and 23 times more than unstabilized soil, which can be seen in the microstructural analysis of the presence of N-A-S-H gel as the main factor in increasing the strength in the geopolymerization process.