Concrete performance using locally produced kaolin

This study presents the effect of incorporating local calcined kaolin on the engineering properties and durability of concrete with water/binder ratios in the range of 0·40–0·60. Blended mixtures with cement replacement of 5, 10, 15 and 20% were designed with a target slump of 150 ± 25 mm. From this investigation, it was found that a 10% replacement level was the optimum level in terms of compressive strength. Beyond 10% replacement levels, the strength was decreased but remained higher than the control mixtures with the exception of water/binder ratio of 0·60. With respect to the durability test, the initial surface absorption at 10 min (ISA-10), the sorptivity and the water absorption were enhanced with higher replacement level regardless of water/binder ratio. A linear equation was developed to determine the superplasticiser dosage for a desired workability based on the obtained results. This investigation has shown that the local kaolin has a potential to be incorporated as blended cement as it improves the durability/permeability and compressive strength in comparison with ordinary Portland cement mixtures.