Effects Of Poly-carboxylic Superplasticizer On Fresh Concrete And Its Mechanism

Invention and application of superplasticizers are looked upon as the third revolution of concrete technology after reinforced concrete and prestressed concrete.In this dissertation, a type of poly carboxylic salt (COPOCA202) as superplasticizer is investigated, and the research is compared to a type of sodium poly-naphthalene sulfonate(UNF-5). The result is that the performance of COPOCA202 is better than that of UNF-5, and high strength concrete with large fluidity can be produced through application of COPOCA202.Viscometer is employed to analyze the effects of the two types of superplasticizer on rheologic properties of fresh cement paste, and changes of interior structure are studied. The tests results perhaps are from the fact that COPOCA202 can destroy inner structure of the paste to more extent than UNF-5.The dissertation probes to the mechanism of poly carboxylic superplasticizer compared with UNF-5. Though the investigation of surface potential and "adsorption amount", the facts are got that COPOCA202 increases less absolute value of the potential than UNF-5, and so do "adsorption amount" which means there are more molecules in aqueous phase than UNF-5. Thus, the dispersion ability of COPOCA202 stems from one or both of steric repulsive force and depletion effect.