ACTIVATION OF RED KAOLIN CLAY AS A POZZOLANIC MATERIAL

Abstract

This work included two stages; in the first stage the optimum burning temperature to convert red kaolin clay to metakaolin was investigated. The red kaolin was burnt in a different temperature (800, 850, 900, 950, 1000, and 1050) ºC for one hour. Many tests was carried out on the cement containing (8)% of calcined kaolin such as normal consistency, setting time, soundness, compressive strength at (3, 7, and 28) days, and pozzolanic activity index at (7, and 28) days. The results show that the optimum burning temperature to convert kaolin clay to metakaolin is (900) ºC. In the second stage the effect of replacing the red kaolin calcined at (900) ºC at a (5, 8, and 10) % by weight of cement on compressive strength of cement mortar at (3, 7, and 28) days, and compared the results with reference mix. The results shows that the mortars contains red kaolin have compressive strength less than the reference mix at (3, and 7) days, but it shows slightly increasing in the compressive strength at (28) day about (100.8, 102.5, and 103.4) % for the mixes containing (5, 8, and 10) % of red kaolin respectively. The results also showed that the mortar containing (10)% red kaolin gives higher compressive strength compared with the mortar containing (5, and 8)% red kaolin at (28) day.