DRYING SHRINKAGE OF HYDROTHERMALLY CURED CEMENTS WITH REACTIVE MAGNESIA AND CLAY BRICK WASTE

摘要

In recent years, worldwide research and development in the cement industry has gathered momentum with　an aim to explore innovative and sustainable methods to deliver environmentally responsible PortlandrnCement (PC) based construction products. This study investigated physical and mechanical properties ofrnautoclaved cement-quartz sand blends with the addition of clay-brick waste (CB waste) and reactivernmagnesia (MgO) with the aim to lower CO_2 emissions through the reduction of PC consumption. Mechanicalrnproperties and drying shrinkage showed improvements with the incorporation of CB waste due to increasedrnamounts and crystallinity of Al-tobermorite. The addition of reactive MgO to PC in hydrothermal conditionsrnwas observed to have a negative effect on the compressive strength. XRD data indicated that MgO did notrntake part in the reaction during the hydration of the cement and may even retard tobermorite formation.rnHowever, the expansive nature from the hydration of MgO to brucite may have compensated for dryingrnshrinkage.