In this paper, we present the design and construction of a remote monitoring system for determining the probability and rate of corrosion of rebar embedded in concrete. We use the ASTM standard C876 technique for the probability of corrosion and the Linear Polarization Resistance method to indirectly obtain the rate of corrosion. The system consists of a communication module using GSM and GPRS cellular networks which provide remote measurements. The device was used to evaluate corrosion with reference electrodes of copper/copper sulfate and graphite on Type I Portland cement specimens of 15cm in diameter and 30cm in length. The results of the measurements were compared to a commercial system, revealing similar values to the data obtained in the field and the laboratory.

Introduction Corrosion of concrete rebar has been established as the main factor of the premature deterioration of reinforced concrete structures. The occurrence of such phenomena represents mostly the durability problems of the material, especially when the structure is subjected to the chloride ions presence (in marine or high salinity enviroment) and large amounts of carbon dioxide (CO2 ), processes known as chloride penetration and carbonation respectively[1,2,3]. Once the corrosión process has appeared in rebar, these begin to generate large stresses on the layer of concrete around them (due to the iron oxides that accumulate around the transversal area) which over time can generate microcracks, cracks and failure on the general structure[4]. Given the importance of preserving civil structures, is evident the strong necessity of obtaining a system with great flexibility to perform the estimation in situ of the corrosive state, capable to dispose the information for immediate consultation anywhere with minimum internet access. Therefore, the present work shows the development and implementation of a system for in situ monitoring of corrosion, for any reinforced concrete structure based on ASTM C876-91[5] standard for measuring half-cell potential, with which it is possible to determine the corrosion probability of rebar in reinforced concrete structures. Also, the equipment performance is presented by using different reference electrodes as Copper / Copper Sulfate (Cu -CuSO4 ), silver / silver chloride (Ag / AgCl) and Zinc / Zinc Sulfate (Zn -ZnSO4 ). Experiments and Results It was obtained a system for in situ monitoring of corrosion for reinforced concrete, that allows to estimate the corrosion probability on rebar, where the user send a text message, to start the test in the system and in return, via GPRS (General Packet Radio Service), the equipment disposes the data trend on a graphic trough a web server on an internet domain (figure 1). The system was tested on a building of the University complex, where its performance was evaluated using three different reference electrodes, obtaining an error over the measurement, between the standard and the system, of 6.62% (figure 2). References (1) ROA-RODRIGUEZ, G., APERADOR, W., DELGADO, A. Calculation of Chloride Penetration Profile in Concrete Structures. International Journal of Electrochemical Science. v. 8, p. 5022-5035, Apr. 2013 (2) HA WONG, S., VELI, S. Corrosion Monitoring of Reinforced Concrete Structures - A Review. International Journal of Electrochemistry Science, v. 2, p. 1 – 28, Jan. 2007. (3) SATHIYANARAYANAN, S., PANJALI NATARAJAN, K., SARAVANAN, S., SRINIVASAN, G. Corrosion monitoring of steel in concrete by galvanostatic pulse technique. Cement & Concrete Composites, v. 28, p. 630-637, May. 2006. (4) SHAMSAD, A., Reinforcement corrosion in concrete structures, its monitoring and service life prediction––a review. Cement & Concrete Composites, v. 25, p. 459 – 471, May. 2003 (5) ASTM Standard C876-09, 1991, Standard Test Method for Corrosion Potentials of Uncoated Reinforcing Steel in Concrete. ASTM International, West Conshohocken, PA, 2003, DOI: 10.1520/C0876-09.

En este artículo se presentan los resultados de la caracterización del material obtenido en impresión 3D compuesto por poliuretano termoplástico, en donde se seleccionó este material ya que fue el más adecuado para la fabricación de un dispositivo que absorba y disperse la energía. Adicionalmente, se adecuo a una chaqueta que con el propósito de usarlo en la disciplina de ciclismo. En el diseño se tuvo en cuenta diferentes tallas a medida del usuario y un proporcionado ajuste al codo, en donde se recibe la mayor energía de impacto. Se determinó la resiliencia del material polimérico a los que se les vario la estructura interna de relleno, dejando como variable fija la densidad de rellenado. El tipo de estructura interna del material con mayor energía almacenada antes de la deformación plástica fue el poliuretano termoplástico con rellenado cúbico, con el software ANSYS se determinó el comportamiento a comprensión y a tensión de la estructura

The materials used in the orthopedic surgery present changes in their characteristics due to the human body has an influence by means of the reactions among the implant and the tissue; caused by corrosive phenomena mainly where the material interacts with a biological fluid, and wear processes owing to the fictional forces that must withstand. When corrosive and wear processes occur simultaneously, is produced an acceleration of both processes due to its synergy, which increases the risk that the patient presents health complications and / or catastrophic failure of the implant. [1-3] As a result, it was obained equipment that performs wear and corrosion test simultaneously, which has a sample holder coupled to a lever arm, that rotates on its pivot controlling the applied load on the sample when comes into contact with the abrasive ball. The ball is fixed among two coaxial supported on bearings, where one of them is driven by DC motor with an encoder with the purpose of ensuring the velocity and number of revolutions of the test. To simulated biological conditions, it was adapted a potentiostat which has an electrochemical cell composed by: the reference electrode -RE (Ag/AgCl), the auxiliary electrode-AE (Platinum wire) and the sample-WE. The electrodes are immersed in Hank’s solution which acts as electrolyte and fluid simulated biological fluid. In the figure 2 is obtained the Tafel polarization curves in function of the bilayer number [TiCN / TiNbCN]n. The curves are strongly dependent on the number of bilayers, which indicates the influence of the interfaces present in a multilayer. The films show higher electrochemical potential in comparison with the substrate without coating which confirms the protective effect of the coatings. This behavior is characteristic of the multilayer structures; in consequence of the increase of the bilayer number, the number of pores, the density and the number of interfaces also increases for all the thickness of the system. It leads to the required energy to move the Cl- ions through the interface of coating/substrate with liberty is higher, therefore the ions that get to the substrate are less due to the direction change which experience the Cl- ions when they find a new interface. In general, the tests allowed to determine the decrease in mass loss of the material as a consequence of the synergistic effect of the micro-abrasion wear and the corrosion in a simulated a biological environment. Additionally, it was observed a protection due to the protector layer generated by the interaction among the coating and the simulated biological fluid. References [1] J.B. Park, Biomaterials Science and Engineering. New York: Plenum Press. 1984. Pp. 213-185. [2] J.Breme, R. Thull and C.J.Kirkpatrick. Metallic Bio-material Interfaces. Weinheim: Wiley-VCH, 2007. [3] S. Fukazaki. H. Urano and K. Nagata. Adsorption of Protein Onto Stainless-Steel Surfaces, Journal of Fermentation and Bioengineering, vol1, pp. 6–11, 1995.