Abstract
Cement pastes of different compositions were hydrated in a geothermal solution with the simultaneous action of high temperature (150 °C) and pressure (18 MPa) for 7 days. The influence of solution on phase composition and compressive strength of pastes was investigated based on the comparison with hydration in water and using TGA, XRD, FTIR, 29Si, and 27Al NMR. The geothermal solution accelerated hydration and pozzolanic reactions. A higher amount of more thermally stable products was formed. Undesired transformation to crystalline α-C2SH in the samples with the highest C/S ratio was restricted. The uptake of carbonates from the solution led to an increased amount of calcite. As a result, increased compressive strength values were determined. Preferential incorporation of Al3+ into the structure of C-(A-)S-H or hydrogrossular phases depended on the composition of cement pastes.
Published Version
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