Effect of Water-Retaining Admixtures on Some Properties of Self-Compacting Concretes . Part 1 . Rheological Characteristics of Cement Compositions

An analysis is made and the development of a single method for assessment of compatibility of superplasticizers and cement according to the rates of bleeding of cement with additives and critical shear stress of cement suspensions is attempted. It is established that the value of bleeding coefficient of cements with superplasticizers and water-retaining agents is differ- ent but the character of bleeding is the same. The introduction of water-retaining additives makes it possible to reduce the bleeding of cements. The use of water-retaining and stabiliz- ing substances leads to increasing the dispersity of a solid phase and the molecular interaction between the particles. This causes the appearance of many contacts between them and leads to the creation of a spatial structural grid that provides the high water-retaining capacity. Selection of the dosages of superplasticizers and water-retaining agents for a particular cement can be assigned according to the value of limit shear stresses of cement suspensions. The increase in ultimate shear stresses of cement compositions with a superplasticizes and water-retaining additive indicates an increase in their water requirement. This factor is necessary to take into account when designing the composition of self-compacting mixes, especially pumped with the use of concrete pumps

L.I. KASTORNYKH, Candidate of Science (Engineering),
A.V. RAUTKIN, Master student,
A.S. RAEV, Master student

Don State Technical University (1, Gagarina Square, Rostov-on-Don, 344010, Russian Federation)

1. Mchedlov-Petrosyan O.P. Himija neorganicheskih stroitel’nyh materialov [Chemistry of inorganic building materials]. 2nd ed. Rev. Moscow: Stroyizdat. 1988. 304 p. 
2. Nesvetaev G.V. Technology of self-compacting concrete. Stroitel’nye Materialy [Construction Materials]. 2008. No. 3, pp. 24–28. (In Russian). 
3. Nesvetaev G.V., Davidyuk A.N., Khetagurov B.A. Self- compacting concrete: some of the factors that determine the fluidity of the mix. Stroitel’nye Materialy [Construction Materials]. 2009. No. 3, pp. 54–57. (In Russian). 
4. Usherov-Marshak A.V., M. Ziac Compatibility – the theme of the concrete Sciences, and resource technology concrete. Stroitel’nye Materialy [Construction Materials]. 2009. No. 10, pp. 12–15. (In Russian). 
5. Usherov-Marshak A.V., Babaevskaya T. V. The effective ness of the additives – the subject of concrete Sciences and technology of concrete. Tehnologii betonov. 2012. No. 7–8, pp. 53–55. (In Russian). 
6. Zotkin A.G. Strength compatibility of cements with super plasticizers. Tehnologii betonov. 2014. No. 9, pp. 22–26. (In Russian). 
7. Tolmachev S.N., Belichenko E.A., Brazhnik A.V. Development of the technological criteria of compatibility of su perplasticizers with cements. Stroitel’nye Materialy [Cons truction Materials]. 2016. No. 5, pp. 60–65. (In Russian). 
8. Petrova T.M., Serenko A.F. Determination of the com patibility of cement with additives of surfactants on the kinetics of the limiting shear stress. Tsement i ego primen enie. 2007. No. 5–6, pp. 82–83. (In Russian). 
9. Kastornykh L.I., Sinitsyna N.A. The study of the proper ties of lightweight self-compacting concretes. Vestnik of the South Ural state University. Series “Architecture and con struction”. 2014. No. 4. Vol. 14, pp. 47–51. (In Russian). 
10. Afanasyeva V.F. Assessment of the effectiveness of the cements used in the Russian construction. Tehnologii be tonov. 2013. No. 1, pp. 12–15. (In Russian). 
11. Bazhenov Y.M., Demyanova V.S., Kalashnikov V.I. Modificirovannye vysokokachestvennye betony [Modified high-quality concrete]. Moscow: ASV. 2006. 368 p. 
12. Butt Y.M., Berkovich T.M. Vyazhuschie veschestva s poverhnostno-aktivnyimi dobavkami [Astringent substances with surface-active additives]. Moscow: Promstroyizdat. 1953. 248 p.