Properties of hot-pressed calcium aluminate cements

Simultaneous heating and pressing techniques were applied to ordinary calcium aluminate cements (40% Al2O3) and high aluminate (72%) cement. The compressive strength of the former, when hot pressed at 50, 000 psi, 250°C, 12hr. is 51, 000 psi, while the latter is 45, 000 psi. The strengths of comparable standard pastes after 24 hours curing are 6, 000 and 4, 300 psi, respectively. Hot pressing decreases the porosity from 22% in standard pastes to about 4%. Mechanical properties of hot pressed calcium aluminate cements are similar to those of comparably treated portland cements despite compositional and some microstructural differences. XRD, DTA, IR absorption, SEM, leaching, thermal shock, and thermal stability were also studied.