SANDY SOIL STABILIZATION WITH COPPER SLAG- BASED GEOPOLYMER AND COPPER SLAG AND SILICA FUME BLEND GEOPOLYMER

Nowadays, cement is one of the most used materials in civil engineering. However, a large amount of energy is used in the cement manufacturing industry and produces greenhouse gases, which are the main contributor to environmental issues. Therefore, researchers and engineers look for alternative materials that can satisfy the physical and the mechanical properties of cement with relatively small adverse effects on the environment. The purpose of this research is to stabilize the sandy soil using copper slag-based geopolymer instead of cement to increase the compressive strength of soil and to decrease the environmental effects. Two types of alkali solution (Solutions A and B) were used to activate Geopolymer raw material composed of slag. Solution A, contained sodium hydroxide, silica fume and water. Solution B, contained sodium hydroxide and water. In this study, two types of coarse and fine-grained copper slag were used to determine the effect of particle size on the mechanical properties of soil. In addition, the effect of adding silica fume as part of the geopolymer raw material was investigated for evaluation of the compressive strength of soil. The results showed that adding finer particle size copper slag and silica fume, as part of the geopolymer raw material, increased the compressive strength. The results of compressive strength tests were compared between copper slag-based geopolymer stabilizer and Sandy soil stabilized with cement. XRD analysis was used to study the crystalline phase of geopolymer raw material and Sandy soil. furthermore, the reason for cracks occurring in stabilized specimens was studied. Hydrate lime was used to improve the mechanical properties of the stabilized soil with geopolymer by preventing transverse and longitudinal cracks. SEM Photos were taken to analyze and compare infrastructure of the stabilized specimens with high and low compressive strength. SEM images showed that specimens with high-strength have denser particles and more highly uniform structure. The results of this study indicated that waste and sub-products of the industry including copper slag and silica fume can be used instead of cement for soil stabilization.