Applicability of solidified soil induced by tuff-based geopolymer for ramming erosion area of earthen site

In northwest China, the erosion diseases of earthen sites are severe, and ramming is a common protective method. To improve the durability of the ramming section, the applicability of solidified soil induced by tuff-based geopolymer was explored through a series of tests. The results show that, with the dosage of tuff powder, the concentration of potassium hydroxide and sodium silicate increasing, the unconfined compressive strength of the solidified soil first increases and then decreases, the disintegration mass decreases, and the color difference increases. The shrinkage rate decreases with the increase of tuff powder dosage and potassium hydroxide concentration but increases with the sodium silicate concentration increasing. Through optimization analysis, the optimal proportions of tuff powder dosage, concentration of potassium hydroxide and sodium silicate were determined to be 12 %, 3.4 mol/L, and 0.3 mol/L, respectively. Under the above condition, unconfined compressive strength, disintegration mass, shrinkage rate, and color difference were 4.41 MPa, 10.77 g, 0.97 %, and 2.31, respectively, which meet the requirements of earthen site reinforcement. For the solidified mechanism of tuff-based geopolymer, potassium hydroxide and sodium silicate can dissolve some minerals in the tuff powder and loess. Sodium silicaluminate hydrate, potassium silicaluminate hydrate, and calcium silicate hydrate gel are generated, which fills the soil pores and bonds the soil particles to effectively enhance the properties of the soil. This study will provide a material proportioning scheme and theoretical support for the treatment of erosion diseases in earthen sites.