Environmental concerns and sustainable development require increased replacement of cement. Most of previous studies have shown that the compressive strength of cement-based composites is maximized with a 20% content of metakaolin. We investigated composites prepared by replacing ordinary Portland Cement (OPC) with 30 to 50% of metakaolin (MK) and addition of appropriate amount of hydrated lime, which were ordinary cured for 2, 28 or 90 days. Hydration products and microstructure of the pastes were determined by X-ray diffraction (XRD), differential thermal analysis/thermal gravimetry (DTA/TG) and mercury intrusion porosimetry (MIP). MK was produced by calcination of kaolin from a Serbian deposit, which contained a high level of impurities.
Replacement of OPC with 30% of MK achieved 28 days compressive strength equivalent to that of the control mix. Higher replacement levels, 40% and 50%, combined with the addition of hydrated lime, achieved satisfactory relative strengths of 94% and 87%, respectively. The positive contribution was particularly pronounced after 90 days for a composite containing 50% of MK. The results clearly showed a possibility of obtaining composites having acceptable compressive strength with reduced cement content in accordance with environmental and sustained development requirements.
Ilić, B., Radonjanin, V., Malešev, M., Zdujić, M., Mitrović, A.: Effects of mechanical and thermal activation on pozzolanic activity of kaolin containing mica. Appl. Clay Sci. 123, 173–181 (2016). doi:10.1016/j.clay.2016.01.029CrossRefGoogle Scholar
Ilić, B., Radonjanin, V., Malešev, M., Zdujić, M., Mitrović, A.: Study on the addition effect of metakaolin and mechanically activated kaolin on cement strength and microstructure under different curing conditions. Constr. Build. Mater. 133, 243–252 (2017). doi:10.1016/j.conbuildmat.2016.12.068CrossRefGoogle Scholar