Desempenho de aditivos bombeáveis classe c 25 com aditivos plastificante e superplastificante

Abstract

Polyfunctional additives are responsible for improving the characteristics of the concrete in its fresh and hardened state by acting mutually in more than one function. The chemical bases that make up this type of additive have the power to catalyze these properties according to the content used in their dosages. In addition, they are able to minimize the amount of water used in cement hydration, influence the process of cement particle hydration, improve the workability of the mixture, increase the mechanical strength and consequently increase the structure durability. The functional groups of the additive molecules known as lignosulfonates generate charges by adsorbing on the surface of the cement particle causing electrostatic repulsion. While the group of polycarboxylates create physical barriers caused by long chains of polymers, a phenomenon known as a steric effect. Thus, an in-depth study on the technical performance of two chemical bases with different performances is necessary, and subsequently the economic viability analysis for the production of these concretes. In this work, the technical performance was investigated through the analysis of workability and compressive strength, in detriment of the Cost Contribution Margin, exclusively of the inputs, aiming to choose the additive that satisfactorily corresponds to the pre-established parameters. The workability of concrete, measured by class S100 abatement and class C25 mechanical strength, were analyzed considering two different traits with different additive contents and chemical bases. The results showed that both met the base trait criteria, however, the polycarboxylate based polyfunctional additive presented better technical-financial viability, with expressive gain of compressive strength (MPa) in relation to the cost in reais (R $).