Influence Of Welan Gum On Cement Clinker Phases Hydration

Since the components of cement is complex, three main phases of cement clinker were studied in this paper, that is the experiment were conducted in three system, C3A-CaSO4 system, C3S-H2 O system and C2S-H2 O system. By the changes of Zeta potential, phase and amount of hydration product and ions concentration, influence of welan gum and mixture of welan gum and superplasticizer were measured.It was shown that in C3A-CaSO4 system, welan gum adsorbed on C3 A or AFt and hindered the precipitation of AFt on C3 A making it suspended in pore solution, thus difficult the move of AFt nucleation and delayed the AFt crystallization and growth.C3S, C2 S and C-S-H were negative and a Ca2+ layer were adsorbed and formed a protective film. Welan gum adsorbed on Ca2+ layer, then the chain were connected into net, similar to the influence on AFt, the C-S-H and Ca(OH)2 crystallization were hindered by welan gum. However, because of the dispersion of welan gum, C3 S and C2 S connected with water enough, so increased the amount of hydration products later.When welan gum mixed with FDN, little competitive adsorption was exist, that the mixing method influenced little on hydration process, while for PCE, welan gum compete obviously with PCE, among if adding PCE at first and welan gum added after 2min, PCE would express good water reduce property and benefit to crystallization of hydration product thus enhanced the mortar strength.