Abstract: Laterite is prone to form as aggregate due to its high clay content, leading to a difficultly in uniformly mixing itwith lime. Meanwhile, is the weak acid property of laterite promotes the interaction between the lime and laterite, which shows a significant influence on the final treatment effects. In this paper, the causes of the weak acidity of laterite are firstly studied through the charges distribution characteristics of water molecules and clay minerals. Then, the interaction between lime and laterite is simulated through soaking the lime-treated laterite in the acid and alkaline solution respectively. Based on the results, the method to inhibit the lime-laterite interaction by metakaolin is proposed. Laterite with two groups size, mixed with different dose of metakaolin and lime are adopted to conduct the unconfined compressive strength tests. The results show that compared with the laterite treated with lime alone, neither excessive nor insufficient metakaolin has contribution to its strength improvement, and the best treatment effect can be obtained with the dose of 5.0% metakaolin, which verifies the feasibility of metakaolin to inhibit the lime-laterite interaction . Reactions between metakaolin and limecan form not only the silicon and aluminate cementation bonded by ionic bond but also the reticular cementation bonded by covalent bond. Since the latter has a significant ability toresist erosion by acid, the internal reason of lime-laterite interaction undermined by metakaolin is interpreted.

Key words: metakaolin, lime, aggregate size, laterite, strength