Competitive adsorption and mechanism of cement particles and stone powder on polycarboxylate superplasticizer.

In view of the problem that the high content of stone powder in manufactured sand and the change of applied environment will lead to the significant decline of the workability of concrete, in this paper, the change law of the fluidity of cement paste, its correlation with the ambient temperature, and the competitive adsorption performance of stone powder and cement on poly-carboxylate superplasticizer(PCE) were studied under the condition of equal substitution of stone powder. Meanwhile, the mechanism of competitive adsorption was revealed. The results show that the fluidity of cement paste replaced by 20% stone powder decreases by 5.3% and 24.3% respectively at 20 °C and 40 °C, compared with pure cement paste, the influence of temperature on the fluidity is significant. The results of adsorption amount show that when the solid content of PCE is 0.3%, the adsorption amount of PCE on cement particles reaches saturation, and the saturated adsorption amount is 0.41 mg/g, the adsorption amount of PCE on stone powder is 0.58 mg/g, and continues to increase with the increase of PCE content. The results show that the adsorption capacity of PCE on stone powder is stronger than that of cement particles and the increase of ambient temperature will accelerate the adsorption of PCE on the surface of cement particles and stone powder. [ABSTRACT FROM AUTHOR]