The Synthesis And Property Of The Shrinkage Reducing Agent Of Poly-Acrylate

Because concrete can be made diversified form and dimension, and have favorable wearing, and it's cost is very low, concrete is the used very widely and generous, but the shrinkage of concrete is puzzling all the engineers, especially the pumping concrete, high performance concrete and high intension concrete. So it is necessary to invent a new shrinkage reducing agent.The fist shrinkage reducing agent come from Japan in 1982,made from Sanyo chemistry industry corporation and Japan cement corporation. from then on, the shrinkage reducing agent was widely used in far east area, especially in Japan from 1983. the shrinkage reducing agent can be used in flat, road surface, bridge, wall and so on. The fist shrinkage reducing agent appear 20 years. Because of it's high cost, it don't used widely.The article analyze the concrete drying shrinkage mechanism, find the major factors of affecting the drying shrinkage, analyze the lack of shrinkage reducing agent, who be of low molecular weight and line chain, design a new shrinkage reducing agent——Shrinkage Reducing Agent of Poly-Acrylate. The shrinkage reducing agent of poly-acrylate is mainly composed of crylic acid,cinnamene,poly-glycol,solicitating agent,chain transferring agent and activator, which come by these processes of polymerization,esterifing and neutralization to form a pectinate polymer, which have a high molecular weight and many poly-oxidative alkenes.The article confirm the proportion of diversified raw and processed materials, and confirm the technical parameter of polymerization,esterifing and neutralization. The qualities of this shrinkage reducing agent adding to the concrete are 1.2% of the qualities of the cement in the concrete. The shrinkage reducing rate can reach to 70% at the 7th day, and the shrinkage reducing rate can reach to 40% at the 28th day. It doesn't reduce the intension of the concrete. It can have an ability of 10～18% of reducing water rate. It can retard the setting time of the concrete. It also can be sprayed on the concrete members, and have good shrinkage reducing rate effect. It can be a kind of conserving agent.