This work is part of the DURACON Ibero-American project, which seeks to characterize concrete durability under environmental conditions, based on reinforced concrete sample exposure in at least two different atmospheres (marine and urban), for each of the 11 countries in the project. Specimens were exposed to the environmental conditions of 13 Mexican sites (8 urban and 5 marine atmospheres). Concrete specimens were 15 x 15 x 30 cm, with 6 rebars each, and three concrete covers (15, 20 and 30 cm). Two concrete mixtures were used with water/cement ratios of 0.45 and 0.65, respectively. Six reinforced and six plain concrete specimens were placed on each exposure site. Environmental data was collected on each exposure site, including rainfall, relative humidity, time of wetness, temperature, wind velocity, and carbon dioxide/chloride concentrations. Corrosion rates and potentials, as well as concrete resistivity were measured in the reinforced samples. Carbonation depths were measured on the plain ones. The present work focused on the measurements of environmental parameters during the first two years of exposure to analyze the potentiality and the probability of carbonation-induced corrosion, and the evaluation of the corrosion initiation period for the reinforcing steel on the 13 Mexican exposure sites.
Experimental study on the mechanical behavior of polyphenylene sulfide (PPS)based composite laminates reinforced with carbon and glass fibers subjected to different strain rates under compression load is reported. Quasi-static tests have been carried out using an electromechanical universal testing machine at three different strain rates, while dynamic tests were done using a split-Hopkinson pressure bar (SHPB) apparatus at two pressure setups in the gas chamber. High-speed imaging system was used to monitor failure process during dynamic test, and these images were used to measure strain by digital image correlation (DIC) in order to compare the DIC-based measurements performed with the SPHPB strain gauges and quasi-static results. Fractography analysis was also performed to identify the main failure mechanisms induced at different strain rates.
This work presents the influence of turbulent flow on corrosion kinetics of API X80 steel immersed in synthetic seawater at room temperature and atmospheric pressure. In order to control the turbulent flow conditions, a rotating cylinder electrode (RCE) was used. Different rotation speed were studied: 0 (or static conditions), 1000, 2000, 3000, 4000, 5000 and 7000 rpm. The electrochemical techniques used in the corrosion study were cathodic polarization curves and total polarization curves, using a conventional three electrode cell. The results of cathodic kinetic analysis show that the turbulent flow has influence at all rotation speeds, that is to say, the corrosion process is controlled by a mass transfer process associated with the oxygen diffusion from the bulk electrolyte to metal surface. In addition, the corrosion rate shows a strong increase as the rotation speed of the RCE increases and consequently increasing the Reynolds number.
This work presents the study of the effects that the electrolyte and the turbulent flow have on the electrochemical kinetic of the super duplex stainless steel (SDSS) immersed in synthetic seawater at room temperature, atmospheric pressure under static and turbulent flow conditions. In order to control the hydrodynamic conditions, a rotating cylinder electrode was used (RCE) at four rotation rate (1000, 3000, 5000 y 7000 rpm). A typical three-electrode electrochemical cell was used. Cylindrical working electrodes made of SDSS were used in all experiments as working electrode, sintered graphite bar as auxiliary electrode and a saturated calomel electrode as reference. In order to analysis the corrosion phenomenon, the technique electrochemical impedance spectroscopy was used during 24 hours of the exposure time. According to the impedance technique, the corrosion rate decreased as the exposure time in seawater increased. In addition, the effect of the turbulent flow on corrosion process was really negligible. On the other hand, it is important to point out that the oxygen diffusion was the limiting process in the SDSS corrosion.
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