Role of the structure of synthetic Al(OH)3 on the properties of sulfoaluminate cement-based materials

A promising approach to accelerate cement hydration has been discovered, wherein superfine particles are utilized to introduce additional nucleation sites for the growth of hydration products. This study investigated the effects of synthetic amorphous aluminum hydroxide (AH3), bayerite, and boehmite on SCGM properties. The results show that amorphous AH3 acted as nucleation sites for the growth of bayerite and ettringite (AFt), bayerite provided nucleation sites for the growth of monosulfate (AFm) and AFt, and boehmite could offer nucleation sites for the growth of AFt. Additionally, synthetic AH3 at pH 12.5 releases AlO2−, and the amount of AlO2− released and the additional generated AFt were the largest for amorphous AH3, followed by bayerite and boehmite. Owing to the synergistic effect of the crystal nuclei and AlO2− released from AH3, synthetic AH3 can promote cement hydration, alter the pore structure of the hardened paste, and improve compressive strength at all ages.