Study On Improving Anti-clay Performance Of Polycarboxylate Superplasticizer By Anti-clay Agent

In recent years,with the continuous development of concrete in the direction of high strength and high performance,the research of polycarboxylate superplasticizer has been deepened,and the varieties of functional polycarboxylate superplasticizer have been increasing.However,one of the particularly prominent problems is that the sensitivity to mud has seriously affected the application of polycarboxylate superplasticizer.In particular,the high mud content of natural sand and the use of mechanism sand make it urgent to solve the adaptability problem of polycarboxylate superplasticizer.In general,the development of anti-clay polycarboxylate superplasticizer and small molecule anti-clay agent are used to solve such problems.However,the high price of functional monomers of anti-clay polycarboxylate superplasticizer limits its practical application.The small molecule anti-mud agent is simple and convenient,low cost,easy to operate on site,and is an important method to solve such problems in practical application.However,there are few studies on the compounding technology of small molecule anti-clay agent and the law and mechanism of improving the anti-clay performance of polycarboxylate superplasticizer.Based on this,this paper developed a small molecule anti-clay agent to improve the anti-clay performance of polycarboxylate superplasticizer,studied the influence of different formulations on the fluidity of cement paste containing clay,cement mortar containing clay and cement mortar containing machine-made sand,optimized the compounding technology of anti-clay agent,and revealed the law of anti-clay agent improving the anti-clay performance of polycarboxylate superplasticizer.The results show that the anti-clay agent not only improves the initial fluidity,but also significantly improves the fluidity and loss over time.The research on anti-clay agent in this paper provides an effective technical scheme and scientific support for the production and application of anti-clay agent in actual concrete.The main contents are as follows :1.The effects of different clays such as bentonite,mica soil,kaolin and montmorillonite on polycarboxylate superplasticizer were studied.The effects of different components including complexing components(maltitol and tartaric acid),adsorption components(polyethylene glycol 2000 and polyether alcohol),dispersion components(sodium metabisulfite and sodium hexametaphosphate)and retarding components(sodium gluconate and hydroxyethylidene diphosphate)on the fluidity of cement paste containing montmorillonite were studied by single factor experiment.The results show that the best anti-mud additive in the ionic complexing component is maltitol;the best mud-resistant additive in the soil adsorption component is polyethylene glycol 2000;the best anti-clay additive for clay dispersion components is sodium metabisulfite;the best anti-clay additive in the retarding component is sodium gluconate.The small molecules with the best anti-mud effect in different components were selected.The orthogonal experiment of five factors and four levels was used to study the effect of various chemical substances on the anti-mud performance of anti-mud agent in cement paste containing montmorillonite.The results showed that the order of influence was polyethylene glycol 2000 > sodium gluconate > maltitol > sodium metabisulfite,and the optimal synthesis ratio of anti-mud agent was obtained.2.The influence of different components on the fluidity of cement mortar containing montmorillonite standard sand was studied by single factor experiment.The experimental results show that the best anti-clay additive in the complexing component is maltitol;the best anti-clay additives in the soil adsorption components are polyethylene glycol 2000 and polyether alcohol.The best anti-mud additive in the stable component is sodium gluconate.The influence of each component on the fluidity of cement mortar containing montmorillonite standard sand was studied by orthogonal experiment with five factors and four levels.The results showed that the order of influence was polyether alcohol > polyethylene glycol 2000 > maltitol >sodium gluconate,and the anti-clay agent ratio suitable for montmorillonite standard sand cement mortar was obtained.The cement mortar containing montmorillonite standard sand was prepared according to the standard method by using the compound anti-clay agent and polycarboxylate superplasticizer,and the mortar experiment was carried out.The 3d,7d and 28 d compressive and flexural strength of the cement mortar containing montmorillonite standard sand were measured.The results show that the anti-clay agent effectively improves the strength of 3d and 28 d,and the strength of 28 d is more obvious.3.The effect of different components on the fluidity of machine-made sand cement mortar was studied by single factor experiment.The results showed that the best anti-mud additive in ion complexing component was maltitol,the best anti-mud additive in soil adsorption component was polyether alcohol,the best anti-mud additive in soil dispersion component was sodium metabisulfite,and the best anti-mud additive in retarding component was sodium gluconate.The small molecules with the best mud resistance were selected in each component,and the influence of each component on the fluidity of machine-made sand cement mortar was studied by five-factor four-level orthogonal experiment.The results showed that the degree of influence was sodium gluconate > polyether alcohol > maltitol > sodium sulfite,and the anti-mud agent compound ratio of machine-made sand cement mortar was successfully obtained.