Abstract: Laterite is prone to aggregate and difficult to disperse. When treated with lime, it actually adheres to the surface of aggregates in fact, resulting in inhomogeneous distribution inside and outside. In this study, two groups of laterite were selected with different aggregate sizes ( 5.0 mm and 0.5 mm). A series of mechanical and hydraulic properties tests, such as shrinkage test, compression test and direct shear test, were conducted, and the effects of hardening and intergranular cementation on the surface of treated laterite aggregates were evaluated. The results showed that aggregate size, initial water content, and treated method significantly affected the treating effect. Compared with the treatment with lime alone, the metakaolin-lime cooperation method was better, with reduced compressibility, increased cohesion and reduced shrinkage. However, the treatment effect was influenced by the aggregate sizes of laterite, and the improvement of mechanical and hydraulic properties of laterite declined with the increasement of aggregate size. Based on this, it can be inferred that after treatment, “hard shell” was formed on the surface of laterite aggregates, which improved the compressive resistance and surface roughness of the aggregate. Cementations were formed between aggregates, inhibiting the shrinkage behavior and improving the cohesion, but after aggregate size increased, the influence scope of metakaolin-lime was limited to the surface of aggregates, and the aggregate size effect counterbalanced the treatment effect of metakaolin-lime.

Key words: laterite, aggregate, hardening, cementation, metakaolin