Synthesis And Application Of Sodium Polyacrylate Viscosity Modifier For High-strength Concrete

With the gradual development of national building construction,new requirements have been placed on concrete in the quality and process of engineering construction.High-strength concrete has become the mainstream of industry development due to its good durability,workability and economy.In the process of mixing high-strength concrete,admixtures play an extremely important role.As a new generation viscosity regulator,sodium polyacrylate viscosity regulator can meet the requirements of modern engineering on the viscosity,slump and strength of concrete.Therefore,this subject has developed a high-performance sodium polyacrylate viscosity modifier.Viscosity regulator in order to develop high performance polyacrylic acid sodium,make full use of the molecular design of polyacrylic acid sodium viscosity regulator has the characteristics of flexibility,in the study with the method of the aqueous solution polymerization,choose the most commonly used HPEG monomer to provide molecular side chain,choose acrylic as polymerization of monomers,acrylamide as the auxiliary monomers,potassium persulfate sodium bisulfate as initiator system,formaldehyde-time methyl allyl sulfonate as chain transfer agent,to join the room temperature response additives,XL-1 to control the temperature at 30 ? ± 5 ?,with viscosity reduction can create a kind of polyacrylate sodium viscosity regulator NT-JN.The effects of different acid ether ratio,amount of chain transfer agent,amount of initiator,dropping time and holding time on the properties of polyacrylate sodium viscosity regulator were studied by single factor variable analysis.Through analysis and comparison,a better synthesis ratio was obtained,that is,when the acid ether ratio was 3.5?1,chain transfer agent was 0.4 %,initiator dosage was 0.4 %,dropping time was 3 h,holding time was 0.5 h,the best performance of the polyacrylate sodium viscosity regulator.The molecular structure,adsorption property,molecular weight and molecular weight distribution of NT-JN were characterized by infrared spectroscopy and molecular weight absorbency test.The microscopic characterization analysis showed that,compared with the other two commercially available viscosity reducing agents JP-W1 and JP-W2,NT-JN had better adsorption property and excellent molecular arrangement structure and molecular weight distribution.The adaptability of NT-JN and other commercially available viscosity reducing agents to different cement,the adaptability of three mineral admixtures of fly ash,ore powder and silica fume to replace cement and the sensitivity to temperature were compared.Studies have shown that NT-JN has a better adaptability to cement and admixture and a lower sensitivity to temperature than other commercially available viscosity reducing agents.The mixture of NT-JN and PC-XM,a polycarboxylic acid water reducer,was carried out in different proportions.When the content of NT-JN was 0.3 % ~ 0.6 %,the concrete performance was optimized.