石灰-红黏土互损行为与偏高岭土减损机制

Behavior of lime-laterite interaction and anti-erosion mechanism of Metakaolin

红黏土成团现象突出,导致石灰处治红黏土时难以拌和均匀;同时,红黏土呈弱酸性,石灰与黏土会发生互损作用,最终影响处治效果。首先,从水分子与黏土矿物的电荷分布特征角度,解释了红黏土呈弱酸性的原因;然后,通过酸、碱溶液浸泡石灰处治红黏土,模拟石灰-红黏土的互损行为;最后,提出应用偏高岭土抑制"石灰-红黏土"互损的方法。为此,选择两种团粒尺寸的红黏土,掺入不同比例的偏高岭土和石灰,并评价其无侧限抗压强度。结果表明,与仅用石灰处治的红黏土相比,掺入偏高岭土过多或过少都不利于其强度提高,掺量为5%效果最佳,验证了偏高岭土抑制"石灰-红黏土"互损行为的可行性。偏高岭土与石灰快速反应,不仅生成了以离子键结合的硅、铝酸胶结物,还生成了以共价键结合的网状胶结物,而且后者具有明显的抗酸侵蚀能力,从而解释了偏高岭土能够减少石灰-红黏土互损的内在原因。

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.