Research On The Structure And Application Of The Polycarboxylic Acid Type High Performance Concrete Water-reducer

This article research work take the country "973" plan project "High performance Cement Preparation And Application Basic research" the sub- topic chemistry sur- medicinal preparation to the high performance cement hydration advancement influence and the "2007-K4-3" plan project "Functions controlled Polycarboxylate of high-performance concrete water reducer research" as a background,discussed the relation between structure and function of water reducer. The main achievements are listed as follows:1.Polycarboxylate-type superplasticizers with different side-chain structure are studied by analyzing fluidity,setting time,concentration of Ca²⁺,chemical shrinkage of cement paste and XRD of hydrated cement blended with water reducers.The result shows that the density of carboxyl(--COOR) and polyethylene glycol(--OC₂H₄--) of polycarboxylate-type superplasticizers produces an effect on cement hydration process.As the density of(--OC₂H₄--) increased,the setting time of the cement paste is elongated,the fluidity is better,while the fluidity preservation of cement paste is worse.The concentration of Ca²⁺ when the cement paste hydrated for 1min and 1h is the most when the mol ratio of(--COOR):(---OC₂H₄--) is 1:3,and the chemical shrinkage of the paste is the largest.At the same time,the XRD analysis of 1d and 28d also shows that when the mol ratio of(--COOR)."(--OC₂H₄--) is 1:3, the diffraction peak of Ca(OH)₂ is the sharpest.That is to say the hydration process of the cement is the most sufficient.Therefore,if the mol ratio of(--COOR): (--OC₂H₄--) is controlled reasonably,it can be improve the dispersivity and the retentivity of polycarboxylate-type superplasticizers,also it can adjust the setting time and the chemical shrinkage of cement.2.A series of different side-chain polycarboxylic superplasticizers(KH) were synthesized in this paper.Ues the KH to study it's effect on the initial performance and hydrates of cement by the analyzing of fluidity,setting time,resistance ratio, chemical shrinkage of cement paste and mechanichal property of 1 day,7day and 28 day.The results indicate that the fluidity is better,while the fluidity preservation of cement paste is worse with the increasaing of the length of PEO side-chains.At the early hydration of cement,KH inhibits the hydration of C3A and C3S,and the inhibition becomes weaker with the increasaing of the length of PEO side-chains.3.Through gathers the carboxylic acid to the synthesis is reduces water medicinal preparation a series of concrete,the cement experiment,finally indicated the self-restraint gathers polycarboxylic acid type water-reducer have the good dispersivity and the dispersive retentivity,the configuration concrete has the good fluidity and the fluid retentivity;when Mixing 1%of the concrete the quantity,the water reducing rate is possible to achieve 25%,performance much better than naphthalene type water-reducer,almost the same as overseas similar product performance.