The corrosion process in reinforced concrete structures, exposed to marine or industrial environments, causes the appearance and growth of cracks. As a consequence, this produces a slow degradation of the material physical properties, steel fragilization and a decrease of the bond strength and steel reinforcements, cross section, affecting its static and dynamic behavior.In the second half of the twentieth century, the importance of constructions' service life was noticed, so different techniques have been developed to predict the Residual Life of existing structures, in order to increase it. This situation has a significant economic impact on society.This paper presents a non-destructive technique to predict the Residual Life of reinforced concrete beams having different cracking levels, as results of steel reinforcement corrosion, considering the variation produced in the dynamic behavior, through the variation of the first natural vibration frequency.The reinforcement corrosion is an electrochemical process that can be quantified by measuring the intensity of the current on the concrete surface. In this paper, to simulate the corrosion process, a current is externally applied to the studied structure reinforcement and then crack widths and vibration natural frequencies are measured. Based on these measurements a mathematical model is proposed to predict structure remaining life. ª 2014 Production and hosting by Elsevier B.V. on behalf of Housing and Building National Research Center.

No abstract

Over their lifetime, concrete structures can suffer from different pathologies, one of them is exposure to high temperatures, which diminishes their load‐bearing capacity. This study describes how different concrete types were exposed to high temperatures. To simulate fire extinction, where the temperature of the overheated concrete descends suddenly, different cooling systems were applied: slowly cooling in the open air and fast cooling by spraying different water volumes. Several physical–mechanical characteristics were analyzed such as compressive strength, splitting tensile strength, porosity, capillary suction, and carbonation depth. Ultrasound nondestructive tests were conducted to quantify deterioration. A petrographic study using a stereomicroscope and microscopy of polarization was performed on thin sections to evaluate aggregate composition and concrete characteristics, focusing on interface areas. Physical and mechanical properties were affected by the increase in temperature, with damage worsening through the appearance of cracks and microcracks when water is used as a cooling system.

No abstract