Estudo experimental da influência da interface espaçador/concreto na corrosão de armaduras desencadeada por íons cloreto.

Abstract

Currently, many cases of premature deterioration in reinforced concrete structures have been recorded. One of the most outstanding is the corrosion of reinforcements, which may occur through chloride ions or by a carbonation front. In order to guarantee the required design coverage in reinforced concrete structures, spacers are used. With adequate cover, the durability of the piece tends to be higher. In contrast, the spacer/concrete interface can become a fragile point for the entry of aggressive agents, such as chloride ions, for example. The objective of this work was to conduct an experimental study to analyze the influence of the spacer/concrete interface on the corrosion of reinforcements triggered by chloride ions, when using different types of spacers. From this, three families of prismatic reinforced concrete specimens were molded, they are: without spacer (reference), with mortar spacer produced on site and with industrialized mortar spacer. These test specimens were submitted to the chloride ion penetration induction test by means of cycles of drying and partial immersion. Throughout the test, the corrosion potential was measured. Also, complementary tests of ultrasonic wave velocity, presence of chlorides by the colorimetric method with silver nitrate and gravimetric loss of the mass of the reinforcements were carried out. Tests were also carried out on the spacers themselves. After the analysis of all the results, it was concluded that the specimens with industrialized mortar spacers were the ones that favored the beginning of the corrosion, evidencing the direct influence of the presence of the spacers in the corrosion of concrete reinforcement.