Ceramics-Silikáty 48 (3) 110-116 (2004)

EFFECT OF CURING TEMPERATURE ON THE THERMAL EXPANSION AND PHASE COMPOSITION OF HYDRATED LIMESTONE-SLAG CEMENT

M. S. Morsy, M. Heikal

The materials used in this investigation were ordinary Portland cement (OPC), granulated blast-furnace slag cement (GBFSC) and limestone (LS). The slag cement containing limestone shows small thermal expansion and shrinkage coefficient in comparison to neat OPC pastes. This is mainly due to the pozzolanic activity of the granulated slag as well as the filling effect of limestone. It was found that the partial substitution of slag by 5 wt.% LS improves the compressive strength. As the curing temperature increases, the C-S-H phases are deposited within the pore system, which can accommodate larger amounts of hydration products. This fact leads to relatively high compressive strength values of GBFSC when compared with OPC pastes. As the amount of limestone increases (15 wt.% LS), the compressive strength diminishes. The presence of 15 wt.% limestone changes the morphological shape of C-S-H crystals from fibers to crumbled foils with small fibers embedded of Ca(OH)₂ phase.

Keywords: Curing temperature, Thermal expansion, Limestone, Slag cement, Phase composition