Study on the erosion resistance of composite ultrafine cement-based grout-reinforced bodies in aggressive ionic environments

To address the challenges of grouting in water-rich weak soft rock formations and the degradation of grouted structures under ionic erosion, this research conducted formulation experiments utilizing ultrafine slag powder and sodium silicate-modified ultrafine cement materials. Through these investigations, we successfully developed a novel composite ultrafine cement grouting material demonstrating enhanced injectability and improved resistance to chemical erosion. Through erosion experiments on grouted solids and a combined approach of macroscopic performance testing and microscopic structural characterization, the mechanisms of ion-induced degradation in grouted solids were revealed. Key findings include: (1) The incorporation of ultrafine slag powder enhances hydration activity, promotes further hydration of cement, and improves the compactness of the hardened grout. (2) The novel composite ultrafine cement grouting material exhibits excellent erosion resistance, retaining over 70% of its original strength after 90 days of exposure to high-concentration ion solutions. (3) Sulfate ions generate expansive reaction products, inducing new cracks and pores within the grouted solids, thereby weakening their structural integrity. Chloride ions accelerate the dissolution of hydration products through chemical reactions, further reducing strength. The degradation mechanisms differ significantly between sulfate and chloride ions. This research provides a theoretical basis for developing grouting materials suitable for water-rich weak soft rock and offers insights into mitigating degradation of grouted solids in aggressive ion environments.