Study On The Properties Of Polymer Modified Cement Mortars For Concrete Structure Repair(PCMR)

Polymer modified cement mortars for concrete structure repair (PCMR) is a kind of materials of polymer modified cement mortars. By adding appropriate polymer in cement mortars, it could achieve the results which improve mechanical and durable properties and strengthen the bond strength between the new and the old concrete, to meet the requirements in concrete structure repair. According to related national standards for the performance requirements of PCMR , this paper tested and chose the raw materials of PCMR on the basis of analyzing the raw materials of PCMR, investigated the influences of mineral admixture, antifoamers and polymers on the properties of PCMR modified by SBR, meanwhile considered the effect of the other polymer emulsions on the properties of PCMR, optimized the composition of PCMR and made it meet the technical requirements of the maximum performance level (PCMR-â…¢level) for the norms of polymer modified cement mortars and concrete structure repair . The main research results of this paper are as follows:(1)The primary tests and analysis of PCMR raw materials showed: the adaptability was good among the polymer emulsions (P1, P5, P7, P8 and P11), polycarboxylate superplasticizer (Sup3) and antifoamers (A1 and A2), then chose material compositions which adapted to five kinds of polymer emulsions and were high fluidity and low air content.(2)The tests and analysis of PCMR modified by SBR showed: the effect of silica fume, fly ash and slag on the fresh and mechanical properties of PCMR modified by SBR were not significant, but antifoamers and polymer had significant influence on their properties. Their mineral admixtures component ratio (C: SF: SG: FA: UEA) = (66:4:10:10:10), the dosage of antifoamers (0.2%) and polymer (10%) were decided, and the modified PCMR had good comprehensive properties.(3)The test and analysis of other polymer emulsions modifying PCMR properties showed: to the fresh properties, the best polymer emulsions of reducing-water effect was P5 , and the worst was P11.For the effect of modification on the workability of fresh mortars, P5 was generally superior to the others. To the mechanical properties, P5 could improve the compressive and flexural strength at early age, and it was generally better than others on the effect of the modification for the adhesive property. Based on good comprehensive properties and low cost, P5 polymer emulsion and its dosage (6%) were decided, and the mechanical properties of mortars modified by P5 could approach the technical requirements of PCMR-â…¢level.(4)Through optimizing the properties of PCMR that the kinds of sand ,sand-binder ratio and curing condition, and testing their durable properties on the optimized PCMR, it can be found that their properties was in low dry-shrinkage ratio, and excellent resistance to frost and chloride- penetration, which could meet the technical requirements of PCMR-â…¢level.By considering comprehensively, PCMR which optimized and modified by P1 and P5, had favorable workability as well as excellent mechanical and durable properties,and it can satisfied the technical requirements of PCMR-â…¢level, which could be utilized in concrete structure repair.