Study on properties and soil solidification mechanism of alkali - activated cementitious materials

Abstract

Due to the low strength and poor durability of soil, it is limited in engineering application. To improve its strength and durability, the alkali-activated (AA) cementitious materials were prepared using industrial wastes, and experiments were performed on AA cementitious materials and solidified soil, including mechanical properties tests, water stability tests, and microscopic properties tests. The results indicate that the content ratio of fly ash and slag can significantly affect the properties of AA cementitious materials, and the maximum 28d compressive strength reaches 36.1 MPa. With increasing AA cementitious materials content (up to 50%) and age, both the compressive strength and tensile strength of AA solidified soil enhance. The microstructure evolution process of soil after solidification includes four stages, including mineral material dissolution, silicon aluminum diffusion, polymerization of low polymer silicon aluminum salts, and polymer soil particle cementation and hardening. The mineral raw material particles and soil particles are effectively bonded due to the adhesion between the reaction products and the mineral material, which improves the performance of the AA solidified soil. The maximum 28d compressive strength of AA solidified soil was 3.6 MPa, the maximum tensile strength was 1.05 MPa, and the maximum water stability coefficient was 0.89.