Metakaolin concrete at a low water to binder ratio

This paper investigates the performance of concrete containing metakaolin (MK) at a low water to binder ratio of 0.3. Portland cement (PC) was partially replaced with 0–20% MK. Testing included, compressive strength, ultrasonic pulse velocity (V), dynamic modulus of elasticity (Ed) and length change. Specimens were either cured in water or in air at 20 °C. The results indicate that the performance of MK concrete at low water to binder ratio is not different from that at higher water to binder ratios reported in a previous investigation. The maximum contribution of MK to strength occurs at 14 days of curing in that the relative strength of MK concrete shows a maximum value at that curing time as found in a previous investigation. The optimum replacement level of cement with MK is about 15%. Linear relationship exists between V and Ed for air cured and water cured specimens. A systematic increase in MK content of up to at least 20% leads to a decrease in shrinkage and an increase in expansion after 56 days of curing. Correlation between the various properties is also conducted.