Influence Of CFBC-titanium Slag Complex Auxiliary Cementitious Materials On Compatibility Between Cement And Superplasticizers

The components of concrete were more and more complex, which leads to the compatibility between composite cementitious materials and water reducer agent became the key factor on affecting workability of concrete. Among them, low-grade auxiliary cementitious materials influence the compatibility more seriously. Circulating fluidized bed coal combustion fly ash (CFBC) and titanium slag were urgently waited for using, therefore the influence of the CFBC-titanium slag composite cementitious materials on the compatibility between cement and superplasticizers had been researched in this paper.The polycarboxylate superplasticizer and naphthalene water reducer had been used in this experiment. Firstly, the influence of CFBC-titanium slag ratio and fineness of CFBC on compatibility between cement and superplasticizers had been studied through marsh tone test method. Then, the result of compatibility got from marsh tone method had been analysed through quantitative analysis method. Finally, the mechanism how auxiliary binding materials affected the compatibility between cement and superplasticizers had been explored from adsorption property of water reducer agent and the Zeta potential, setting time, rheology and thixotropy of pastes.Results showed that the adsorbance of superplasticizers by cementitious materials particles was increased and the hydration rate of pastes was accelerated, which raised the saturation point, bleeding point of superplasticizers and the loss rate of marsh time in 60 minutes of pastes, with the increase of CFBC-titanium ratio. Also, the marsh time in five minutes of pastes was lengthened for the enhancement of yield stress and plastic viscosity. The grain sizes of CFBC particles were diminished, the pore structure were broken and the specific surface areas were increased by grinding process. Therefore, the marsh time in initial and final periods of pastes was shortened and the saturation point and bleeding point of superplasticizers was decreased while grained CFBC replace original cells for the adsorbance of water reducer agent, the yield stress and plastic viscosity of pastes decrease. Compared with naphthalene water reducer, polycarboxylate superplasticizer dispersed cementitious materials particles better and kept the fluidity of pastes for longer time, even though it couldn’t increase the zeta potential of pastes. In addition, the result of qualitative evaluation and quantitative analysis of compatibility with cement and superplasticizers could match each other well. It showed that the function of polycarboxylate superplasticizer and naphthalene water reducer were affected by the content and fineness of CFBC, respectively.Under this research, we suggested that the polycarboxylate superplasticizer may be chosen while the CFBC-titanium slag ratio was less than 1, or using naphthalene water reducer. Although both CFBC and titanium slag are solid wastes, they can learn from each other well while being used in cement system well with appropriate ratio and content after compositing.