The Study On Synthesis And Property Of Polycarboxylic Acid Superplasticizer

The polycarboxylic acid superplasticizer has been paid more and more attention by concrete engineering world, because of its higher water-reducing ratio, lower slump loss, and excellent enhancement effect. Research and development of new product with more excellent performance and applicability has important theoretical and practical value, which is also the main development direction of concrete additive.In this paper, A self-made new-style monomer N-glycinymaleamic acid (denoted as GMA) was used and combined with other materials to synthesize a polycarboxylic acid superplasticizer with new structure, and its synthesis process and properties were discussed in detail.Firstly, the greater material factors of product performance were selected through orthogonal experiment. Further, four-substance copolymerized optimal conditions were determined by single factor analysis and synthesis process optimization, that was, GMA/AA/SAS/APEG mole ratio of 1.7:1.4:0.6:1, the initiator dosage of 4.5wt%, the reaction temperature of 75°C, the reaction time of 4h, and the copolymer PC-N1 possessed preferable dispersion and slump retention ability.On the basis of the optimization of process, a certain amount of maleic anhydride MA and self-made monomer TX were introduced, and water-reducer PC-N2, PC-N3 were prepared, respectively. When mixing 0.2 wt% neat PC-N3 in cement, the initial fluidity of cement paste reached as high as 293 mm, and fluidity was 288 mm after 2 hours. The anticipated target for synthesis of superplasticizer was realized.Simultaneously, to further improve product performance, compound liquid (FP) with sulfonic acid group was prepared. The synergistic effects of polycarboxylic acid water-reducer mixed with FP, sodium sulfamate (SS) and sodium gluconate (PN) were studied. The results showed that FP had the good plasticization effect to the cement. The fluidity of cement paste maintained about 290 mm in 2 hours after mixing FP and 0.2 wt% PC-N2. The sodium gluconate has served as one kind of good retarder, and also has the excellent plasticization effect to the cement.The synthesis PC series water-reducer has the better compatibility to many kinds of cement and higher performance-price ratio. It indicated that water-reducing ratio achieved 21.3% when mixing 0.14 wt% of synthetical PC water-reducer applied in the C30 concrete, and its strength performance surpassed those of marketed PC-3 and mixed 0.6 wt% naphthalene water-reducer.