Influence of Lime Dust on Chloride Binding Capacity of Fly Ash-Cement Paste

Abstract

The influence of the way and the volume of adding lime dust to fly ash-cement pastes on chloride physical adsorption capacity, chemical combination capacity and binding capacity of fly ash-cement pastes is investigated by adsorption equilibrium method. The results show that with the volume of lime dust as cement replacement raising, the amount of chloride physically adsorbed by fly ash-cement pastes reduces, while the amount of chloride chemical combining is firstly increase, and then decrease, and it reaches the maximum when the lime dust content is 10% , that of chloride binding is firstly increase, and then decrease, which reaches the maximum when the lime dust content is 5%. In addition, with the volume of lime dust as fly ash replacement increasing , the volume of chloride physically adsorbed by fly ash-cement pastes reduces firstly, and then raises, reaching the minimum when the lime dust content is 6%. Whereas, volume of chloride chemical combining and binding both decrease gradually with the increase of lime dust contents. When the population of lime dust as cement or fly ash replacement is low(less than 15% for cement and 9% for fly ash), effect of lime dust content on chloride binding capacity of fly ash-cement pastes is not obvious (under 7.5%).