Study On The Influence Of PCE Series Superplastcizer On Concrete Performance And Its Engineering Application

With the rapid development of China’s economy and society,the construction of engineering projects has been growing rapidly in recent years,followed by a large consumption of building materials.Excessive development has brought problems such as lack of resources,environmental pollution and the decline of raw material quality to some areas.These problems make most of the projects are faced with the problems of poor performance of concrete,too fast slump loss,poor pouring quality,insufficient strength and so on.In order to solve these problems,the engineering community often adopts admixture methods,such as increasing the amount of superplasticizer and adding mechanism sand regulator.However,with the increasing amount of superplasticizer and the compatibility of other admixtures,the bleeding segregation of concrete may occur.Therefore,the engineering community needs a high performance concrete with good initial fluidity and small slump loss and less sensitivity to the content.This paper introduces polycarboxylic acid superplasticizer and self-developed PCE-SA(PCE polycarboxylic acid)superplasticizer with sulfonic acid group,PCE-EG superplasticizer with grafted ester group and PCE-TCD superplasticizer with grafted ester group and mixed sodium citrate to cement paste fluidity test,cement mortar fluidity,concrete slump test,concrete strength test,concrete chloride diffusion test and concrete freeze-thaw cycle test,In order to study the effect of PCE series of superplasticizer agents on cement slurry flow degree,mortar flow degree,concrete slump,expansion degree,concrete strength and compactness were studied respectively.The effects of different groups on cement dispersion performance and the sensitivity of coarse aggregate to superplasticizer agent were studied,Analyses the practical application effect of self-developed superplasticizer in engineering,experimental results show that :(1)The PCE-SA superplasticizer of polymeric sulfonic acid group can improve the dispersion performance of cement,however,excessive content can easily cause bleeding segregation;PCE-EG superplasticizer grafted with ester group can improve cement dispersion in the early stages,after a while,as the ester groups react,replenish depleted superplasticizer,the dispersion of cement is gradually increasing,showed slow release effect;Grafting ester group and adding sodium citrate PCE-TCD superplasticizer can adsorb to cement particles,improve cement dispersion,and-COOH releases free water from flocculants,it has slow release and retarding effect;(2)The sulfonic acid group and ester group grafted with a single component in superplasticizer are sensitive to raw materials such as aggregate,with the constant addition of coarse aggregate,it is possible to reduce the content of effective superplasticizer in the mixture by adsorption of superplasticizer molecules by aggregate,thus,the effect of cement dispersion under the same amount of superplasticizer becomes worse,with PCE series of superplasticizers,each mixing logistics degree is concrete < cement mortar <cement paste,under the action of each superplasticizer,the change law of cement paste,cement mortar and concrete performance is basically consistent;(3)The electrostatic repulsion caused by the adsorption of PCE-SA、PCE-EG and PCE-TCD superplasticizers and the steric hindrance caused by the long side chain make the cement paste more dispersed and uniform,the sustained release of ester group makes ettringite more closely arranged during hardening of concrete,can improve the performance of concrete,raising the strength of 28 d concrete by 2～7 percent,at the same time,the dense arrangement of layered and rod-like crystals makes the internal pores of concrete small,less through pores,good resistance to chloride ion penetration,improved durability and frost resistance,it has certain engineering application value.