Sonochemical synthesis of ettringite from a powder mixture suspended in water

Aqueous suspension containing Ca(OH)(2), Al(OH)(3) and gypsum (CaSO4. 2H(2) O) powders was subjected to ultrasound irradiation under atmospheric pressu re to investigate its effect on synthesis of ettringite (3CaO . Al2O3. 3CaS O(4). 32H(2)O). irradiation of ultrasound to the suspension enables us to f orm ettringite in the product, and the sonochemical synthesis reaction reac hes the equilibrium by about 120 min. Addition of excess amount of Ca(OH)(2 ) powder is effective in consuming the remained gypsum in the product, lead ing to the high yield of ettringite. Heating the suspension at about 80 deg rees C, which is the same degree in the ultrasound irradiation, for 480 min produces tri-calcium aluminum monosulphate (CAM). The formation of CAM pla ys a significant role in delaying the synthesis reaction of ettringite in t he suspension. (C) 2000 Elsevier Science S.A. All rights reserved.