Effect of CaMg(CO3)2 on hydrate assemblages and mechanical properties of hydrated cement pastes at 40 °C and 60 °C

The effect of additions of limestone and dolomite powder on the properties of blended cements cured at 40 and 60 °C was investigated using a multi-method approach. The presence of limestone leads to the formation of hemi- and mono-carbonate and to the stabilization of ettringite at 40 °C. An increase of temperature to 60 °C results in the destabilization of ettringite and formation of monosulfate in the limestone cement. The dolomite is almost depleted in the cementitious matrix over the hydration time at the studied temperatures. As a result, the formation of hydrotalcite is observed which binds part of the alumina from clinker dissolution. At 60 °C, no monosulfate is found and the CSH contains less alumina in the presence of dolomite in comparison to when limestone is present. The dolomite dissolution increases the strength at higher temperatures as a result of the additional hydrotalcite formation.