Abstract: The interaction mechanisms between different clay minerals and polycarboxylate superplasticizer (PC) were discussed with XRD, IR and TOC, saturated water absorption and fluidity.The results show that the side chains of PC can be intercalated into the interlayer of montmorillonite (MMT), thereby causing the interlayer absorption, whereas PC is not able to be inserted into the interlayer of kaolinite, sepiolite and illite;and the only surface adsorption can be observed and the order of adsorption amount montmorillonite > kaolinite > sepiolite > illite.The results of saturated water absorption indicate that the orders of different clay minerals are montmorillonite > kaolinite > sepiolite > illite.The presence of clay minerals would reduce the fluidity of cement-PC paste, and the effect of montmorillonite is the greatest.Therefore, the main reason for the fluidity loss is attributed to absorption of free water and adsorption of polycarboxylate superplasticizer caused by clay minerals.

Key words: polycarboxylate superplasticizer;clay mineral;intercalation;adsorption amount;mechanism