Study On Preparation And Properties Of A New Type Of Superplasticizer

Water reducer is a concrete admixture that reduces water consumption while the slump remains unchanged.Water reducing agents have a dispersing effect on cement particles and can improve the flow of cement,thus saving cement and reducing the amount of water used per unit.The main objective of this thesis is to prepare two new high efficiency water reducing agents and investigate their performance effects.The new poly ethylbenzene water reducing agent was prepared by using poly ethylbenzene tower bottom azeotropes to turn "waste" into treasure and broaden the application channel of poly ethylbenzene tower bottom azeotropes.The use of nano-silica modified polycarboxylate superplasticizers to prepare a new water reducing agent,to study the effect of nano-materials on the performance of cement-based materials.In the first part,we selected two representative stages in the ethylbenzene production process(the new catalyst began to operate and the catalyst activity was the best)to sample the poly ethylbenzene tower bottom azeotropes,and used gas chromatography-mass spectrometry(GC-MS),Coulometric Karl Fischer moisture meter,open flash point tester,Fourier infrared spectroscopy(FT-IR)Gel permeation chromatography(PL-GPC220),thermogravimetric differential scanning calorimetry(TG-DSC)and so on were used to analyze the composition and relative content of the poly ethylbenzene tower bottom azeotropes at different stages,and the main components and average molecular weight of the poly ethylbenzene tower bottom azeotropes were determined.In the second part,the reaction processes of sulfonation,hydrolysis,condensation,neutralization and compounding of poly ethylbenzene tower bottom azeotropes were designed and analyzed for the purpose of exploring the efficient resource utilization of poly ethylbenzene tower bottom azeotropes.The performance of the poly ethylbenzene water reducing agent was characterized by FT-IR,GPC and zeta potential,and the water reducing effect of the poly ethylbenzene water reducing agent was tested by the slurry fluidity and water reduction rate.The ultimate goal of producing a highly efficient cement water reducing agent by using the poly ethylbenzene tower bottom azeotropes as a raw material for resource utilization was achieved.In the third part,we modified the nanoparticles with water reducing agents to provide a research direction for better dispersion of nanoparticles in cementitious materials.Modified allyl ether polycarboxylate superplasticizer(PCE)with short branched chains was synthesized from acrylic acid and allyl glycidyl ether.The optimum process conditions were determined by analyzing the optimum levels of iodine value of PCE and fluidity of cement paste in an orthogonal experimental design.NS/PCE was obtained by grafting nano-silica(NS)onto PCE molecular chains through intermolecular dehydration,thus achieving a homogeneous dispersion of NS in the cementitious material.The results show that NS/PCE has better dispersibility in cement matrix and strong clay resistance,which compensates for the poor dispersion of PCE synthesized from conventional polyethylene glycol(PEG)graft chains in the presence of clay impurities.In summary,two new high efficiency water reducing agents(polyethylene-based water reducing agent and polycarboxylate superplasticizer)have been designed in this thesis,both of which show excellent application potential.