Synthesis and Properties of a Vinyl Ether-Based Polycarboxylate Superplasticizer for Concrete Possessing Clay Tolerance

Common polycarboxylate ether (PCE) superplasticizers that possess polyethylene glycol (PEG) graft chains exhibit high sensibility toward clay impurities contained in concrete aggregates and limestone powder. The presence of clay greatly weakens their dispersing ability. In this study, modified vinyl ether-based PCEs were synthesized from maleic anhydride (MA) and 4-hydroxy butyl vinyl ether (HBVE). We found that successful copolymerization of these two monomers is dependent on incorporation of at least similar to 30 wt % of a maleic monoallcyl ester as an auxiliary comonomer. The resulting terpolymers were characterized and tested for their dispersing ability in cement paste in the absence and presence of montmorillonite. The MA-monoalkyl maleate-HBVE terpolymers are little affected by montmorillonite. Sorption measurements and X-ray diffraction analysis suggest that this novel type of PCE interacts with montmorillonite only via surface adsorption, whereas conventional PCEs possessing PEG graft chains incorporate chemically into the interlayer space of alumosilicates.