Evaluation of Corrosion Rate of Steel Rebars Embedded in Mortar Mixed with Triturated Tire Particles
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Evaluation of Corrosion Rate of Steel Rebars Embedded in Mortar Mixed with Triturated Tire Particles Claudia Berenice Flores Valdez1, Francisco G. Pérez-Gutiérrez2, Imelda Esparza Álvarez1, Orlando Guarneros García2, Sandra Luz Rodríguez Reyna2 1 Instituto de Metalurgia e Ingeniería de Materiales, Facultad de Ingeniería, Universidad Autónoma de San Luis Potosí (UASLP), México. 2 Centro de Investigación y Estudios de Posgrado, Facultad de Ingeniería, Universidad Autónoma de San Luis Potosí (UASLP), México.
ABSTRACT Different materials, such as triturated waste tire (WT) particles, have been proposed as aggregate to improve mortar properties and reduce its cost in recent years. Using WT as aggregate implies material recycling, providing an environmental benefit. Previous studies show controversy on the chloride ion diffusion coefficient in mortar test specimens as a function of the WT content. The objective of this investigation is to evaluate the corrosion rate of steel reinforcement embedded in mortar specimens using WT as aggregate when exposed to chlorides. Electrochemical techniques, mercury intrusion porosimetry and scanning electron microscope were used to measure corrosion rate, porosity and microstructure of mortar matrix, respectively. Corrosion rate and porosimetry results were found to directly correlate for test pieces with 7.5% of WT compared with control samples and test pieces containing 5%, 10% of WT; such results are supported by visual inspection of steel reinforcements. Our results show that substituting 7.5% of sand with WT when preparing mortar provides the optimum protection.
INTRODUCTION Corrosion of steel rebars is one of the main reasons for reinforced concrete deterioration, which increases the cost in construction industry. There are two main mechanisms of steel reinforcement’s corrosion: (1) Concrete carbonation and (2) diffusion of chlorides coming from the environment through the concrete or because of the use of additives containing calcium chloride (CaCl2)[1][2]. It is important to point out that for corrosion onset, it is necessary to overcome a critical concentration of chlorides in the region nearby the steel rebar [3]. Several materials have been proposed for fabrication of concrete in order increase the durability, improve its mechanical properties and reduce its cost [4][5]. One of these materials is waste tire (WT) used as aggregate for concrete. An advantage of using WT is to reuse the large amount of waste tires that are not biodegradable. Taiwan developed a recycling program for waste tires to make asphalt concrete. As a result, paving techniques were improved and most of the ASTM specifications were fulfilled[6]; therefore researchers became interested on studying its properties in order to find new applications and moreover find a useful destination for waste tires. In a recent study to evaluate concrete durability, specimens substituting sand with WT were made, it was found that the chlorides diffusion coefficient resulted 20% and 34% lower for specimens containing 5% an
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