The Synthesis And Performance Of Early Strength Type Polycarboxylate Superplasticizer

Addition agent as an important fifth component of concrete has been widely used in construction projects,and superplasticizer is an indispensable admixture in concrete,can significantly improve the workability of concrete and improve its work performance,So as to achieve the provincial water,saving cement,improve the early strength of concrete and other effects.In this paper,based on the molecular structure design,polyester and polyether type early-strength polycarboxylate water-reducing agent were designed in order to keep the third-generation water-reducing agent in the practical application.Good flow of the case,can effectively promote the cement hydration process,and then to achieve the early strength of cement hydration after the increase.The optimum conditions for the synthesis of polyether polycarboxylate superplasticizer were determined by single factor and orthogonal test:nHPEG:n(AA):n(SMAS):n(SMAS)=1:4:0.26,the amount of initiator APS was 0.3%,the reaction temperature was 75℃,The reaction time of 5 h,AM instead of 17%(mass fraction)of acrylic acid;polyesterpolycarboxy-late water-reducing agent the best synthesis conditions:the amount of esterification reaction material n(PEG-2000):n(MA)=1:3,The reaction temperature was 95 ℃,the reaction time was 5 h,the molar ratio of polymerization monomer was n(PMA):n(AA):n(SMAS)=1:3.2:1.2,reaction temperature 85℃,reaction time 4.5 h,catalyst dosage The total mass of the reaction monomer was 6.0%.The two polycarboxylate superplasticizers were characterized by their structures,such as water reduction,solid content,fluidity and viscosity.The results show that the self-made water-reducing agent has basically reached the expected design.The water-reducing rate of polyether-based polycarboxylate water-reducing agent is 37.9%,the initial fluidity of cement paste is 285 mm,the 2 h is 230 mm,the early strength is increased by 17.7%,At the same time have a better performance.The effects of self-made and commercially available polycarboxylate water-reducing agents on the early hydration process of cement were analyzed by XRD,TGA-DTA and conductivity.The results showed that the synthetic polyether polycarboxylate Commercial polycarboxylate water-reducing agent has a positive effect on hydration,while polyester-type polycarboxylate water-reducing agent to promote the role of hydration is more obvious.Finally,the effect of retarder on the stability of polycarboxylate superplasticizer was discussed by using complex technique.The results show that the flow loss of 120 min is less than or equal to 3.8%.Which provides a technical basis for the regulation of the construction performance of polycarboxylate superplasticizer.