Carbonatação em concreto de alto desempenho em ambientes com diferentes taxas de gás carbônico ( CO₂ ): simulação com câmara de carbonatação acelerada.

Abstract

The studies about the concrete technology have been increasingly developed in order to attend the specific needs of use within civil construction. With this continuous evolution, and with the goal to attend very specific criteria of resistance and durability, the study of High Performance Concrete (HPC) gains strength, mainly with the function of overlapping agressive exposure conditions that many times big constructions are exposed. This work aims to elaborate High Performance Concrete examinations through a specific method of dosage and relate its behavior to the carbonation phenomenon, evaluating the generated effects by the simulation in a controled environment. For this, an accelerated carbonation chamber was built to expose HPC with active silica percentage fixed at 4% in different types of carbon dioxide (CO2). The active silica is a mineral additive that is incorporated to the mixture in order to reduce the porosity and assist the concretes resistance gain. The proportions of carbon dioxide used in this work was of 400 ppm and 700 ppm, with the test bodies being exposed for 7 days in each case. This way, it was sought to demonstrate the advance of the carbonation front in the HPC by two concentration types through an accelerated test. The study had a concrete with dejection of 125mm in its fresh state as a result, relative to its consistency and presented medium resistance to compression of 49,531 MPa in its rough state. Besides that, the concrete presented good results on the porosity characterization tests, with void indexes of 7,95% and water absortion of 3,44%, staying in the limit line the defines it as durable. In this work were also obtained the desired values of 400 ppm and 700 ppm of CO2 inside the carbonation chamber, proving that developing a controlled simulation environment and analyzing the carbonation front is viable.