关键词: 红黏土, 偏高岭土, 收缩, 微裂隙, 吸力

Abstract: The laterite is prone to shrinkage and crack due to dehydration, which may result numerous engineering disasters. Lime (5%) and meta-kaolin (4%) were added into laterite for mitigating their shrinkage behavior through improving moisture sensitivity. The samples were compacted at optimal water content and cured for 180 days. And then, samples were vacuumed and saturated immediately. After that, the saturated samples were dehydrated to predetermined moisture content for conducting a series of tests such as shrinkage, unconfined compressive strength, suction and pore analysis. The results showed that compressive strength of laterite increased at first and then decreased with moisture content reducing, which may be caused by micro-cracks derived ascribing to dehumidification. However, the strength of laterite adding with lime, especially lime and meat-kaolinite mixture, would increase with approaching to dry status, even if which has a slight reduction during drying process. This proved that meta-kaolin and lime were able to inhibit the shrinkage effect of laterite, and increase their overall strength. This may be ascribed to the following reasons, meta-kaolin contains lots of amorphous silicon and aluminum oxides and has an edge-surface contacted structure, both enable meta-kaolin to quickly capture calcium ions in calcium hydroxide solution and form cementation hydrates between grains or particles of laterite.

Key words: laterite, meta-kaolin, shrinkage, microcrack, suction