Influence of a polyurethane-modified polycarboxylate on properties of cement mortar

In this article, a new kind of polycarboxylate (M-PCE) was synthesized at room temperature in the complex initiation system of hydrogen peroxide (H2O2), ascorbic acid (Vc) and ammonium persulfate (APS), by using polyoxyethylene allyl methyl ether (TPEG), acrylic acid (AA), polyethylene glycol (PEG) as raw materials and thioglycolic acid (TGA) as chain transfer agent. Effect of different composite initiation systems and raw material ratios were fully explored. Along with three other polycarboxylates (O-PCE, C-PCE-1, and C-PCE-2), their properties on water reduction rate, strength, drying shrinkage and autogenous shrinkage of cement mortar were investigated. The results showed that the average performance of the prepared M-PCE was the best when the molar ratio of AA to TPEG was 2:1 in the same situation. When the water cement ratio was 0.3 and the dosage of M-PCE was 1%, the strength increased by 24.5%(with 10% slag), the lowest drying shrinkage and autogenous shrinkage were reduced by 21.9%(with 10% fly ash) and 60.1%(with 10% metakaolin), respectively.