Rheological, fresh, mechanical, and durability properties of mechanochemically activated rice husk ash and glass powder/ slag- based geopolymer for grouting and deep mixing

This research investigates the use of mechanochemical activation as an alternative activation technique to overcome the difficulties associated with conventional two-part geopolymers and increase the reactivity of a one-part geopolymer during ambient curing. The study synthesizes ready-to-use geopolymeric precursors through the mechanochemical grinding of raw materials in a solid state, resulting in an eco- and user-friendly geopolymer binder that requires only the addition of water. The binder is then used to prepare geopolymer grouts and deep soil mixes, with properties evaluated and compared to those of slag-based conventionally activated geopolymer (CSG) and ordinary Portland cement (OPC). Four rice husk ash (RHA) and glass powder (GP) replacement ratios are used to investigate the feasibility of using RHA and GP as partial precursors in slag-based mechanochemically activated geopolymer (MSG) binder. Various tests are performed to examine the properties of the resulting grouts and deep soil mixes, including rheological behavior, fresh properties, mechanical characteristics, and microstructure analysis. The results showed that the rheological characteristics and fresh properties of MSG grouts were considerably enhanced in terms of groutability when slag was replaced with 0–30% RHA and GP. In addition, the mechanical characteristics increased with the increased partial replacement of slag with RHA and GP up to 20% and decreased beyond that. In terms of activation mechanism, the mechanochemical activation technique reduced the rheological and fresh properties while the strength increased by 18% compared to the conventional activation method. Microstructural analysis revealed the existence of more unreactive particles in both conventionally activated geopolymer and MSG grout containing 30% RHA and GP. The results also confirmed that MSG grouts had a shorter setting time and more stable bleeding capacity than OPC grout. this study investigates the mechanical and durability properties of soil specimens stabilized with OPC, MSG, and CSG exposed to magnesium sulfate solutions for 60 and 120 days. The results show that MSG-stabilized soil attained the highest UCS, followed by CSG and OPC stabilizers. In addition, the UCS trend of MSG-stabilized soil increased with increasing partial substitution of slag with RHA up to 20% and afterward declined. Meanwhile, the UCS reached the highest when the amount of GP was 10% of the geopolymer stabilizer. The MSG samples with 20% RHA and GP exhibit less visual deterioration, discoloration, expansion, and cracking than other DSM samples. Partial replacement of slag with RHA and GP up to 20% was recorded as the highest residual UCS. Key Words: Grouting, Deep Soil Mixing, Mechanochemical Activation, Geopolymer, Rheological, Strength, Durability, Rice Husk Ash, Glass Powder