Estudo da variabilidade da resistência à compressão e da consistência de concreto usinado utilizando CPII 40

Abstract

Machined concrete gained great space, due to greater control and quality of the mixture, and also to the rationalization of its production. Since it is produced on a large scale, which results in cost savings, which can be equal to or greater than that of concrete produced on site. The fresh concrete, must have workability, so that it can be transported, cast and compacted, rightly. In the hardened state, it must meet the characteristics specified in the project, and the compressive strength is the most used as a specification parameter, denominated ccs of concrete. Technological control in industry concrete becomes paramount, due to variables that can interfere with the fresh and hardened state of the concrete. In order to evaluate the performance of machined concrete, this project studies the variety of compressive strength and consistency of machined concrete. Therefore, sample of concrete was withdrawn from concrete mixer trucks, of resistance classes C20, C25, C30, C35, C40 and consistency classes S100 and S220, for tests in the fresh and hardened state, using cement CPII E 40 and CPII F 40. In the fresh state, tests were carried out to verify the consistency of the concrete, by means of the slumping of the cone trunk. For the hardened state, as tested at 28 days, to determine the compressive strength of concrete. Thus, the compressive strength, the influence of the water-cement ratio of strength and consistency, the influence of the type of cement and the consistency classes comparison were analyzed. As a result, the water/cement ratio influence on the compressive strength and slump of concrete. The type of cement, on the other hand, does not significantly interfere with the compressive strength. Compressive strength and the water/cement ratio present a high dispersion in the results, evidencing a failure in the production process.