بهره برداری و بررسی انقباض کاهش کوپلیمر مواد افزودنی پیوند زده جدید

Four grafted copolymer shrinkage-reducing admixtures(SRA)were synthesized by the radical copolymerization reacted between unsaturated polyether macro-monomer (RPM(V24) RPM(A24) RPM(MA24) RPM(B24)) which contain the same branch chain length of 2400 and acrylic acid(AA). The experimental results showed that the RPM(B24)-AA had the most optimal shrinkage-reducing effect when the number average molecular weight was between 15000∼20000. Compared with conventional polyether shrinkage-reducing admixture (PSRA), the RPM(B24)-AA demonstrated the superior shrinkage reduction performance without the reduction of the surface tension of capillary water significantly. It has been found that the dry shrinkage of hardened cement paste at 90 days was reduced by about 33.1% and the autogenous shrinkage at 90 days by about 58.1% with 2.0% dosage. The results also indicated that, the shrinkage performance of the grafted copolymer shrinkage-reducing admixture was closely related with the hydrophobic of main chain structure and the molecular weight of grafted copolymer.