Examination of sulfate resistance of nano-alumina added ordinary Portland cement paste, focusing on the two different crystallinity of nano-aluminas

Abstract This study examined the influence of crystallinity added nano-alumina on sulfate resistance ordinary Portland cement (OPC) paste. Two crystalline types nano-aluminas (α-and γ-phase) were incorporated in pastes, which exposed to solution. In results, both paste samples having α- and γ-phase aluminas had accelerated compressive strength loss increased length expansion compared sample without alumina addition. particular, rapidly decreased dynamic elastic modulus postulates greatly internal stress likely by formation volume expansive reaction products, such as ettringite, was supported XRD TG results. The greater ettringite due reactive AH 3 (=Al(OH) ) gel higher consumption degree portlandite indirectly indicates active formation, resulting additional from with Na 2 SO 4 A further attack observed γ-alumina for long-term exposure (180 days) mainly gypsum inducing more α-alumina sample.