Influence of cement on mechanical strength of administrator residual soil

The cement has important influence on the mechanical properties of granite residual soil. Kaolinite powder, montmorillonite powder, illite powder and red clay powder are used to replace the fine particles of granite residual soil to remold soil samples. Compression, shear, tensile and disintegration tests are carried out respectively to study the effects of different cements on the mechanical strength of soil. Results show that the soil particle aggregates after kaolin treatment are increased, and a skeleton structure with high strength is formed between the aggregates. However, the existence of large number of pores between the skeletons provides a channel for water intrusion, resulting in enhanced water absorption of the soil. Benefiting from the swelling property of montmorillonite in water, the treated soil surface has fewer pores and dense structure, and the expansive body provides high strength cementation capacity, making the mechanical characteristics of soil significantly improved. The mechanical strength of the soil sample treated with illite is low, but the soil surface appears relatively dense. From perspective of particles dispersed on the soil surface, illite powder is more used as fine material to fill the pores between large particles than as a cement with high strength between soil particles. After physical compaction, the occlusion between particles is enhanced due to compression; At the same time, after a long time of hydration reaction, the cement formed bridge cementation on the particle surface. Under the combined actions above, the mechanical strength of soil has been greatly improved. The type of cement would have a great impact on the mechanical properties. On the one hand, it depends on the characteristics of the cement itself, such as the water swelling characteristics of montmorillonite. On the other hand, it depends on the binding effect of the cement on the soil. The compressive, shear, tensile and collapse resistance of the soil samples are controlled by the binding mode of the cement and the soil sample.