Thermal stability and phase evolution of brick powder-blended cements after exposure to elevated temperatures: A comparison with metakaolin-blended cement

This study investigated the thermal stability and phase evolution of Portland cement pastes containing brick powder (BP) as a supplementary cementitious material (SCM), in comparison with that formulated with metakaolin (MK). The results show that, the higher pozzolanic reactivity of MK enhanced the compressive strength of hardened cement paste (HCP) compared to those of BPs; however, both MK and BP blends exhibited comparable relative residual compressive strength. On the other hand, BP blends showed better volume stability above 400 °C due to its superior thermal stability, arising from the higher thermal history it experienced during the production process. Therefore, it seems that thermal stability of the unreacted MK and BP particles could be a controlling factor in determining the performance of blended HCPs under high temperature. Consequently, compared to MK, BP might be a more promising pozzolanic material to improve the high temperature performance of cementitious system.