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.

In the present investigation, the physical, mechanical and durability properties of six concrete mixtures were evaluated, one of conventional concrete (CC) with 100% Portland cement (PC) and five mixtures of Ecofriendly Ternary Concrete (ETC) made with partial replacement of Portland Cement by combinations of sugar cane bagasse ash (SCBA) and silica fume (SF) at percentages of 10, 20, 30, 40 and 50%. The physical properties of slump, temperature, and unit weight were determined, as well as compressive strength, rebound number, and electrical resistivity as a durability parameter. All tests were carried out according to the ASTM and ONNCCE standards. The obtained results show that the physical properties of ETC concretes are very similar to those of conventional concrete, complying with the corresponding regulations. Compressive strength results of all ETC mixtures showed favorable performances, increasing with aging, presenting values similar to CC at 90 days and greater values at 180 days in the ETC-20 and ETC-30 mixtures. Electrical resistivity results indicated that the five ETC mixtures performed better than conventional concrete throughout the entire monitoring period, increasing in durability almost proportionally to the percentage of substitution of Portland cement by the SCBA–SF combination; the ETC mixture made with 40% replacement had the highest resistivity value, which represents the longest durability. The present electrical resistivity indicates that the durability of the five ETC concretes was greater than conventional concrete. The results show that it is feasible to use ETC, because it meets the standards of quality, mechanical resistance and durability, and offers a very significant and beneficial contribution to the environment due to the use of agro-industrial and industrial waste as partial substitutes up to 50% of CPC, which contributes to reduction in CO2 emissions due to the production of Portland cement, responsible for 8% of total emissions worldwide.

In the present research a corrosion assessment with electrochemical techniques of linear polarized resistance (LPR) and electrochemical impedance spectroscopy (EIS) was made in reinforced concrete that were treated superficially in the curing stage by silicon-based nanoparticles (SN). The concrete was designed with a water/cement ratio of 0.45 and the steels used were AISI 1018 steel and galvanized steel. The SN were obtained through sol – gel synthesis at a temperature 70 °C in a basic medium. After curing, the concrete developed a decrease in pores, due to the reaction of the SN with calcium hydroxide (CH) surface densification of the cementitious matrix was generated by the formation of secondary hydration products. The overprotection against corrosion in both steels was checked with electrochemical techniques.

In the present research the corrosion behavior of AISI 316 Stainless Steel was analyzed, as reinforcement in Green Concrete made with Low Volume of Sugar Cane Bagasse Ash (SCBA) and Silica Fume (SF), compared to AISI 1018 steel. Four concrete mixtures were made, all with a ratio w / c = 0.65, the percentages of substitution were 0%, 10%, 20% and 30%. The specimens were exposed in seawater as an aggressive medium, corrosion was evaluated by monitoring the corrosion potential Ecorr (ASTM C-876-15) and corrosion rate icorr (ASTM G59). The results of Ecorr and icorr after 150 days of exposure show a better performance of AISI 316 steel, with a 10% of probability corrosion and a negligible level of corrosion respectively, the Green Concrete with 30% partial replacement of the CPC by the combination of SCBA-SF presented the best protection against corrosion.

In the present research the corrosion behavior of AISI 316 Stainless Steel was analyzed, as reinforcement in Green Concrete made with Low Volume of Sugar Cane Bagasse Ash (SCBA) and Silica Fume (SF), compared to AISI 1018 steel. Four concrete mixtures were made, all with a ratio w / c = 0.65, the percentages of substitution were 0%, 10%, 20% and 30%. The specimens were exposed in seawater as an aggressive medium, corrosion was evaluated by monitoring the corrosion potential Ecorr (ASTM C-876-15) and corrosion rate icorr (ASTM G59). The results of Ecorr and icorr after 150 days of exposure show a better performance of AISI 316 steel, with a 10% of probability corrosion and a negligible level of corrosion respectively, the Green Concrete with 30% partial replacement of the CPC by the combination of SCBA-SF presented the best protection against corrosion.