Effects of CFB Ash on the Adsorption Mechanism of Polycarboxylate Superplasticiser

The effects of circulating fluid bed (CFB) ash on the adsorption performance of polycarboxylate superplasticiser and the mechanism of this influence on the dispersive property of the polycarboxylate superplasticiser were investigated by determing the cement paste fluidity, total organic carbon adsorption, infrared spectroscopic analyses and ζ potential test. The experimental results show that the addition of an inorganic salt into the mixture to change the content of SO42- and Fe2O3 can improve the adaptability between the CFB ash and polycarboxylate superplasticiser. Adsorption may occur between the polycarboxylate superplasiciser and Fe2O3, SO42- or other components in CFB ash, leading to a significant reduction in paste fluidity. As the content of Na2SO4 in CFB ash reaches 3% or Fe2O3 reaches 9%, the paste loses its liquidity. The organic carbon content in the liquor decreases with an increase in Na2SO4 or Fe2O3 content. Adding some Ba(NO3)2 and Na2S to the liquor can recover the organic carbon content to a certain extent, and the absolute value of ζ potential will increase. The addition of Ba(- NO3)2 or Na2S reduces the adsorption property of Na2SO4 or Fe2O3 in CFB ash on the polycarboxylate superplasticiser.