Browsing by Autor "Rosa Vera"

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Atmospheric Corrosion
(Hindawi Publishing Corporation, 2012) B.M. Rosales; Rosa Vera; Oladis Troconis de Rincón; A. Di Sarli; Jaime Alberto Rocha Valenzuela; Johan Tidblad
Impacto del ambiente tropical en la durabilidad de las estructuras de concreto armado
(2011) Oladis M. Troconis de Rincón; Miguel Sánchez; Valentina Millano; Rafaél Caballero Fernández; Emilia Arzola de Partidas; Isabel Martínez; Nuria Rebolledo; Mirta Barboza; J.C. Montenegro; Rosa Vera
Para demostrar el impacto que tienen los paises tropicales en el comportamiento de las estructuras de concreto armado, se expondran los resultados de mas de cinco anos del proyecto Iberoamericano: “Efecto del Ambiente sobre la Durabilidad de la Armadura” (DURACON). A tal efecto, se prepararon especimenes con y sin refuerzos (relacion a/c 0,45 y 0,65), para las pruebas quimicas, fisico-mecanicas y electroquimicas, utilizando los materiales existentes en cada uno de los diez paises participantes (Argentina, Bolivia, Chile, Colombia, Costa Rica, Mexico, Espana, Uruguay, Portugal y Venezuela), exponiendolos en 46 estaciones. Este proyecto correlaciona la influencia de los parametros meteoroquimicos de ambientes urbanos y marinos sobre el comportamiento de las estructuras de concreto armado. Todos los resultados demuestran la alta agresividad de los ambientes tropicales, siendo Venezuela uno de los primeros, particularmente en zonas donde la temperatura anual promedio es mayor a 25°C. Esto indudablemente amerita mayores exigencias para la calidad del concreto en estos paises
Reinforced Concrete Durability in Marine Environments DURACON Project: Long-Term Exposure
(2016) Oladis Troconis de Rincón; J.C. Montenegro; Rosa Vera; A.M. Carvajal; Ruby Mejía de Gutiérrez; S. Del Vasto; E. Saborio; Andrés A. Torres-Acosta; J. T. Pérez-Quiroz; M Martinez Madrid
This paper presents the results, after a long-term evaluation in marine environments, from an Ibero-American project called “Effect of the environment on reinforcement durability” (DURACON). This project correlates the influence of urban and marine meteorochemical parameters on the performance of reinforced concrete structures in nine countries (Bolivia, Chile, Colombia, Costa Rica, Mexico, Spain, Uruguay, Portugal, and Venezuela). The environment was evaluated using ISO Standard 9223 and the concrete was characterized physically by measuring compressive strength, elastic modulus, total and effective porosity, as well as the effective porosity and resistance to water absorption using the Fagerlund method. To that effect, concrete specimens (with and without reinforcement) were prepared for electrochemical and physical/mechanical/chemical tests using the existing materials in each participating country, following strict procedures that enabled the preparation of similar concrete specimens. Two water/cement (w/c) ratios (0.45 and 0.65) were selected, where 0.45 w/c ratio concrete had a minimum cement content of 400 kg/m3 and the one with 0.65 w/c ratio had a minimum 28-d compressive strength of 210 kg/cm2. Type I Portland cement, siliceous sand, and crushed rock as coarse aggregates (13-mm maximum nominal size) were used. The results showed that the atmospheric aggressiveness was higher in tropical countries, especially when temperature rises above 25°C, with La Voz station (marine) in Venezuela being the most aggressive. Also, the chloride concentration threshold for rebar depassivation onset was much lower (≈0.42%) in a marine tropical environment, such as La Voz in Venezuela, compared to a nontropical one, such as Cabo Raso in Portugal (≈0.89%), with this concentration dependent on rebar depth and influenced by environmental factors such as time of wetness and ambient temperature, and not only from physical concrete properties.