Synthesis And Application Of Composite Micro-crosslinked Polycarboxylate Superplasticizer

With the rapid development of concrete technology and the continuous improvement of various engineering projects,high water-reducing rate,good controlling of concrete slump loss,good adaptability to raw materials and environmental friendliness have become the development direction of concrete water-reducing agent.At present,polycarboxylate superplasticizer exposed some problems,such as poor adaptability to raw materials and worse anti-mud performance,which seriously limits the application and promotion of polycarboxylate superplasticizers.In this paper,for the problems of the traditional comb-type polycarboxylate superplasticizer on the poor adaptability of raw materials,worse anti-mud performance,unstable effect,etc.in the concrete construction process.According to the principle of molecular structure design,a micro-crosslinking polycarboxylate superplasticizer with cross-linking structure was synthesized by adding a crosslinking monomer on the basis of comb-type polycarboxylate superplasticizer and changing the molecular structure of polycarboxylate superplasticizer.Firstly,comb-type polycarboxylate superplasticizer with better performance was synthesized,in the synthesis of comb-type polycarboxylate superplasticizer under the condition of invariable raw material proportioning,join the three types of cross-linked monomer respectively,N,N-methylene double acrylamide?MBA?and polyethylene glycol acrylate?PEGDA-200?,diethylene glycol divinyl ethers?DGDE?,to the preparation of has slightly crosslinked structure of polycarboxylate superplasticizer,select the the amount of crosslinking monomer respectively.Then the crosslinked polycarboxylic acid superplasticizer was synthesized from isopentenol polyoxyethylene ether?TPEG?,acrylic acid?AA?,crosslinked monomer?MBA,pegda-200,DGDE?,mercaptopropionic acid?TGA?,hydrogen peroxide?H₂O₂?and ascorbic acid?Vc?.MBA was selected as the best crosslinking monomer,and the optimum formula for synthesizing micro-crosslinking polycarboxylate superplasticizer was determined by orthogonal test and single factor experiment:n?AA?:n?TPEG?=3.8:1,MBA?H₂O₂?Vc and TGA accounted for 0.4%?1.3%?0.21%and0.55%of the tatal monomer mass respectively.The results of infrared spectroscopy?FTIR?showed that the crosslinking polycarboxylate superplasticizer was successfully synthesized.Comparing the properties of the synthesized cross-linked polycarboxylate superplasticizer.The crosslinked polycarboxylic acid superplasticizer synthesized in this paper has better dispersibility than the comb-type polycarboxylic acid superplasticizer,and it is concluded that the crosslinked polycarboxylic acid superplasticizer MPCS prepared with MBA as the crosslinked single system has the best dispersibility.Compared with polycarboxylic acid superplasticizer from industrial samples,MPCS showed excellent performance in dispersion and retention of cement paste,dispersion and retention of mortar,and water reduction of mortar.At the same time,in the experiment of anti-mud performance,in order to make the net slurry fluidity of cement mixed with clay reach 260±5mm,the amount of MPCS is the least,indicating that MPCS has excellent anti-mud performance.