Influence of magnesium hydroxide content and fineness on the carbonation of calcium hydroxide

Accelerated carbonation material is a kind of air hardening cementitious materials. The influence of magnesium content on the properties of carbonate binder, such as compressive strength, CO2 mass gain degree and products morphology, were investigated. Solid state carbonation method that low water to solid ratio (W/S) of 0.10 was performed in this study. The samples were prepared at a range of compaction pressures (0 MPa–8.0 MPa). And then the samples were exposed at a constant CO2 gas pressure (0.2 MPa) for different carbonation time. The result showed that different calcium to magnesium mole (C/M) ratios has a significant impact on compressive strength and CO2 mass gain degree of samples. The CO2 mass gain degree increased at first, reached the maximum, and then decreased with the increasing C/M ratio. The C/M ratio of that CO2 mass gain degree reached the maximum was 5. The compressive strength not only changed by magnesium content but also influenced by the fineness of magnesium hydroxide, more finer practical size more higher compressive strength. SEM photographs showed that the morphology of carbonated products changed by different compaction pressures and content of magnesium hydroxide.