Evaluating the performance of high volume fly ash-blended-cement mortar individually containing nano- and ultrafine micro-magnesia

This work focuses on the individual impact of nano- and ultrafine micro ma gnesia (N-MgO and UM-MgO, respectively) on the early performance of high volume fly ash (FA)-blended-cement mortar (CM). N-MgO and UM-MgO were synthesized using a thermal treatment of lightweight hydromagnesite at 550 and 1100 degrees C, respectively. Different contents of MgOs (1, 3, and 5 wt% by weight of powder) were individually added to FA-blended-CM. The results revealed that the N-MgO exhibits higher efficiency in the acceleration of early PC-FA system hydration compared to UM-MgO at all addition levels. The addition of 1, 3, and 5 wt% N-MgO to FA-blended-CM has resulted in the enhancement of 3-days compressive strength value by similar to 26, 94, and 103%, respectively; whereas the UM-MgO shows a modest effect. The small particle size, low crystallinity, and high hydration reactivity are the dominant fe atures of N-MgO, which reflect on the enhanc ement of FA-pozzolanic activity accompanied by the acceleration of strength-giving-phases formation at early ages of hydration. To achieve the sustainability, we have recommend the use of N-MgO, as it contributes to cost minimization, energy saving, and the mitigation of carbon footprint.