Preparationand Performance Of Maleic Acid-type Terpoiymer Superplasticizer Of Concrete

The concrete water-reducing agent is one of the most common concreteadmixtures, which can reduce the concrete mixing water substantially under thecondition of remaining the same slump and make the concrete more workableduring the transportation and construction. The traditional concretewater-reducing agents include lignin sulfonate, melamine, naphthalenesulfonated formaldehyde condensates, which have many deficiencies includinglow water-reducing ratios, excessive slump loss of concrete. At present,superplasticizer becomes the researching focus in the field of admixturesindustries, because it performs many advantages of super dispersion in the lowerdosage, higher water-reducing ratios and environmental protection. Now thedomestic studies mainly focus on the (meth) acrylic acid-type superplasticizer.However, it is difficult to control the reaction conditions in the preparations ofthe (meth) acrylate polyglycol monoester, and the toluene is used as awater-carring agent．After etherification reaction, the toluene couldn’t easily beseparated from the solvent and it is difficult to meet the sustainable developmentstrategies about harmony with environment. In this study, mono polyethyleneglycol maleate of MAMPEG and two kinds of maleic acid-types terpolymersuperplasticizer were prepared, and corresponding reaction conditions and waterreducing performances were tested. The main content of this paper was asfollows:(1) Mono polyethylene glycol maleate of MAMPEG was synthesized viaesterification using maleic anhydride (MA) and methoxypolyethylene glycol(MPEG) as main raw materials. The single factor experiments and orthogonalexperiments were investigated. It was shown that the optimum reactionconditions were that the molar ratio of MA to MPEG was1.6:1.0, the dosage ofcatalyst was4.4%according to the mass of MA, the reaction temperature was80℃, the reaction time was7.5h, and the esterification rate of MPEG reachedup to98.59%under these optimum conditions. (2) Polycarboxylate terpolymer superplasticizer of MAPEG-HEA-SMASwas synthesized by copolymerization with esterification intermediate（MAPEG1000）, hydroxyethyl acrylate（HEA）and sodium methallyl sulfonate（SMAS）as main raw materials. The influence of reaction conditions on thecopolymerization and the adaptability for different cement were investigated.Relative molecule mass and its distribution of superplasticizer were measured byGPC. The results showed that when the molar ratio of MAPEG1000to HEA toSMAS was1.0:1.0:0.5, the dosage of initiator was2.5%of total monomer mass,the polymerization reaction temperature was88℃, the original fluidity of cementgrout could reach308mm with the addition of0.45%of this superplasticizer.GPC showed that the mean molecular weightM nand polydispersityM w/Mnof the superplasticizer were7752and2.091respectively. The superplasticizerhad good adaptability to three kinds of cement commonly used in this area andcould meet the requirements of concrete mixture.(3) Polycarboxylate terpolymer superplasticizer of MAMPEG-HAM-SASwas synthesized by copolymerization with esterification intermediate（MAMPEG1000）, methylol acrylamide（HAM）and sodium allyl sulfonate（SAS）as main raw materials. The influence of reaction conditions on thecopolymerization and the adaptability for different cement were investigated.Relative molecule mass and its distribution of superplasticizer were measured byGPC. The results showed that when the molar ratio of MAMPEG1000to HAMto SAS was1.0:1.0:1.0, the dosage of initiator was5%of total monomer mass,the polymerization reaction temperature was78℃, the original fluidity of cementgrout could reach319mm with the addition of0.70%of this superplasticizer.GPC showed that the mean molecular weightM nand polydispersityM w/Mnofthe superplasticizer were6311and2.204respectively. The superplasticizer hadgood adaptability to three kinds of cement commonly used in this area and wasused extensively.(4) The two kinds of self-made superplasticizers were compared with thecommercially available naphthalene water-reducing agents. The results showedthat the performance of self-made superplasticizer was significantly better thanthe naphthalene water-reducing agents. Under the same conditions of mixingamount, the self-made superplasticizer had good dispersion and dispersion retention, basically without loss of the fluidity of cement paste in2hours. SEMshowed that macropore ratio in the cement stone decreased after theincorporation of self-made superplasticizer, and the structure became moredense, which improved the strength and corrosion resistance of cement stone.