Study On Synthesizing Technology And Performances Of Low-cost Modified Melamine Resin Superplasticizer

In this paper die types and performance characteristics of commonly used superplasticizers, die research and application actualities of superplasticizers both in and outside China were introduced in detail. Based on the action mechanisms of superplasticizers, their synthesizing methods and development trends were also discussed.The parameters of synthesizing technology of traditional melamine resin Superplasticizer were optimized, and the distinct parameters were ascertained through the perpendicular experiments. By controlling those parameters, the hydroxymethylated and sulfonated ratios of melamine resin Superplasticizer were enhanced, the performances of product also improved. By substituting cheap activity monomer Urea for partial melamine monomer, the production costs of Superplasticizer can be obviously decreased. The substituting ratio of Urea can reach to 17%, which is the highest level in present. The synthesizing process can be finished in a single kettle. Not only technology is very simple, but also the reaction time is shortened, Therefore, the production efficiency is obviously increased. The general performances of modified melamine resin Superplasticizer JD can be furthermore improved by compounding Amino-Arylsulphonate Phenol Formaldehyde condensate Superplasticizer HPP. Meanwhile, the reaction theories of Urea and compounding mechanisms of different superplasticizers were also discussed.The experimental results showed that the performances of product for Four-step synthesizing method are prior to that for traditional Two-step and Three-step methods, the product for Four-step method can be reserved for a long time. In the synthesizing process, the pH value in hydroxymethylated stage, the reaction time, temperature and the Moore ratio of Sodium bisulfate to Melamine in the sulfonated stage, and die pH value in the condensation stage, are important factors influencing on the performance of JD. When the substituting ratio of Urea reach up to 17%, the costs of JD can be obviously decreased, but the water-reducing ratio of JD didn't come down. By testing according to correlation criterions, the performances of JD such as ratio of water-reducing, ratio of compressive strcngth, effect of accelerating and enhancing strength, ratio of bleeding, air entrainment content, effect of keeping slump value, compatibility with cement, resistance to concrete shrinkage anddamage by freezing and thawing and water-tightness etc are all better than that of the traditional melamine resin superplasticizer SM and naphthalene series superplasticizer FDN. By compounding JD with HPP, the "Overlapping Effect" of two kind superplasticizers was fully manifested. The compatibility of JD with cement and keeping slump value were more improved through this compounding way. Meantime, the bleeding and segregation of HPP were overcome too. Half-industrialization experiment hasn't abnormal phenomenon, the performances of its product are the same as those of laboratorial product.