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Cerâmica

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Abstract

LYRA, J. S.; ROMANO, R. C. O.; PILEGGI, R. G.  and  GOUVEA, D.. Consolidation of policarboxilates containing cement pastes: a calorimetric and rheological study. Cerâmica [online]. 2012, vol.58, n.346, pp. 137-143. ISSN 0366-6913.  http://dx.doi.org/10.1590/S0366-69132012000200002.

Polycarboxylates are frequently used as additives to concrete production in the construction industry. The additive increases the dispersion of the particles, reduces the amount of water, and improves the mechanical properties of concrete in the fresh and settled state. However, although it is well known that polycarboxylate additives enable the production of high performance concretes, their presence may affect on both kinetics and thermodynamics of cement's particles during hydration reaction through consolidation. While the flow of heat released by the hydration reaction can be measured by isothermal calorimetry, concrete consolidation can be measured by oscillatory rheometry. The results obtained separately, when considered together could better illustrate the effect of the additives on the cement setting. This was the main subject in this work. Therefore, cement pastes containing commercial CPIIE-32 were evaluated by simultaneous heat of hydration and rheological measurements with different amounts of polycarboxylate. The results obtained separately, when considered together can better illustrate the effect of additive content during the hardening, and this approach is presented as a main objective of this work. For this, cement pastes formulated with CPII-32 were evaluated according to the variation of the content of polycarboxylate and the results showed that the rate of consolidation(promoted by the joint action of the chemical reaction and particle agglomeration)has direct relation with the level of the additive.

Keywords : polycarboxylate; cement paste; hydration reaction; agglomeration; consolidation.

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