investigation of the properties of the portlandcement of different mineral composition with superplastificators of various type
Journal Title: Вісник Одеської державної академії будівництва та архітектури - Year 2018, Vol 1, Issue 72
Abstract
A binder plays an important role in providing high quality concrete. The change in the mineral composition and fineness of cement grinding leads to disturbances in the colloid-chemical processes of interaction between a binder and water. This began to manifest itself when in the technology of concrete, powerful modifiers – aqueous solutions of superplasticizers began to be widely used. The phenomenon of changes in the properties of cement paste, mortar or concrete mixture, the consequence of which is the change in the properties of concrete, was called «compatibility of cement – superplasticizer» Studies conducted by various authors show that if there is no compatibility between the cement and the chemical additive, the superplasticizer dramatically reduces the effectiveness of the additive. Our research has shown that changes can be expressed in reducing the time for setting the cement test or in the fact that they do not change. The normal density of the cement paste may or may not change, or varies slightly. The safety of mortar or concrete mixtures decreases with time. This respectively will lead to a decrease in the concrete mix and concrete. The aim of the research was to study the influence of superplasticizers of various types on the properties of cements of different mineral composition. To assess the effect of various types of superplasticizers on the properties of cement testing, standard techniques for determining the normal density, the timing of the setting of the cement test, and also the dispersion of the cement and its activity were used. It is shown that the use of polycarboxylate additives leads to a significant elongation of the setting time of cements regardless of their mineral composition. For cement grade CEM 500 with melamine-formaldehyde additive, the setting time is slightly extended. For cement grade CEM 400 with the same additive, reduction in the setting time is observed, which indicates a poor compatibility of the melamine-formaldehyde additive with CEM 400 cement. For cements with a high early strength, it is necessary to reduce the amount of lignosulfonate additive in order to increase the time for setting of cement.
Authors and Affiliations
S. M. , Tolmachov, O. A. , Belichenko, Y. О. , Zakharchenko, Р. М. , Sazhko, V. V. , Khrushch
Keywords
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