No abstract

Reinforced concrete is one of the most used materials in the construction industry, in which the quality specifications necessary for its acceptance must be met. In the present work, the main focus is on studying the correlation that exists between the tests of resistance to compression and bending with the electrochemical test of corrosion potentials, electrical resistivity and ultrasonic pulse velocity. Specimens of hydraulic concrete with a water/ cement ratio, (w/c) = 0.50, were made according to the ACI 211.1 design method, which is based on the physical characteristics of the aggregates and is the most used in the premix plants. The study was carried out during the hydraulic concrete curing stage in which very favorable results were obtained in the correlation that exists between conventional tests and non-destructive and electrochemical tests.

This study analyzes the electrochemical behavior of AISI 1018 steel as reinforcement in concrete exposed to the Xalapa city (urban environment) and seawater (marine environment). Two concrete mixtures were made, with ratio w/c of 0.45 and 0.65, according to the method of ACI 211.1. The specimens underwent three types of curing, the first was submerged in water for 27 days as indicated by the ONNCCE regulations, the second was cured as it is done on oeuvre (moisturizing the elements in the morning and in the afternoon) and the third one exposing to the environment (without applying water), before placing them in the exposition environment. The results of more than 340 days of monitoring of Ecorr and Icorr demonstrate that the marine environment is the most aggressive in the corrosion of reinforced concrete, with a better performance of the concrete of ratio w/c=0.45 and with a curing according to normative.

This research evaluates of the electrochemical behavior of steel bars of the AISI 316 and AISI 1018 embedded in sustainable concrete with partial replacement of CPC 30R by Sugar Cane Bagasse Ash (SCBA) and Silica Fume (SF). The electrochemical techniques used to evaluate the corrosion were half-cell potential or Ecorr -ASTM C-876-15- and the Linear Polarization Resistance Technique (LPR) - ASTM G59-. Ecorr and Icorr results indicate after more than 300 days of exposure to the marine environment (3.5% NaCl solution), a high resistance of AISI 316 steel, with Ecorr values lower than -200 mV indicating a 10% probability of corrosion, and a level of negligible corrosion, with values less than 0.1 µA/cm2 in the three mixtures, with sustainable concrete values slightly lower. The results indicate a resistance of more of almost 100 times greater than AISI 316 steel compared to the results obtained in AISI 1018 steel.

This research evaluates the behavior corrosion of galvanized steel (GS) and AISI 1018 carbon steel (CS) embedded in conventional concrete (CC) made with 100% CPC 30R and two binary sustainable concretes (BSC1 and BSC2) made with sugar cane bagasse ash (SCBA) and silica fume (SF), respectively, after 300 days of exposure to 3.5 wt.% MgSO4 solution as aggressive medium. Electrochemical techniques were applied to monitor corrosion potential (Ecorr) according to ASTM C-876-15 and linear polarization resistance (LPR) according to ASTM G59 for determining corrosion current density (icorr). Ecorr and icorr results indicate after more than 300 days of exposure to the sulfate environment (3.5 wt.% MgSO4 solution), that the CS specimens embedded in BSC1 and BSC2 presented greater protection against corrosion in 3.5 wt.% MgSO4 than the specimens embedded in CC. It was also shown that this protection against sulfates is significantly increased when using GS reinforcements. The results indicate a higher resistance to corrosion by exposure to 3.5 wt.% magnesium sulfate two times greater for BSC1 and BSC2 specimens reinforced with GS than the specimens embedding CS. In summary, the combination of binary sustainable concrete with galvanized steel improves durability and lifetime in service, in addition to reducing the environmental impact of the civil engineering structures.