Examination of Corrosion On Steel Structures By Innovative Nano Sol-Gel Sensors

ABSTRACT Corrosion of steel and steel reinforced infrastructures is urgently needed to address, since most of them have been in service for a long time and aging at a rapid pace. This project is exploring a robust sensor system that can accurately determine the corrosion state of steel structures during service; thereby, giving a chance to accurately estimate the durability and prevent catastrophic failure. This paper addresses preliminary work on sol-gel sensors to detect corrosion. As one of the most ubiquitous and mobile ions, chloride contacts and diffuses into the steel and thus leads to corrosion. Sol-gel is an amorphous, mechanically stable, inert, and porous material that has been found to change its conductivity as a function of the amounts of chloride it absorbs. Therefore, sol-gel sensors may be attached to the steel to detect the amounts of available chloride for corrosion. The sensors can be tailored for its sensitivity to chloride concentration, dimension, and compatibility to sensor circuit. We have found that the sol-gel sensors exhibit a systematic trend in detecting the existence and the concentration of chloride ion. The methods of sol-gel preparation, characterization, and responses to chloride concentration are investigated and reported in this study. INTRODUCTION The integrity and health of civil infrastructures are of critical importance to public safety and welfares. Corrosion of steel causes deterioration of infrastructure thus threatening its serviceability and durability. It was reported that corrosion was a leading cause to premature failure of steel and steel-reinforced concrete bridges.¹ The corrosion of infrastructure is needed to address urgently since, at present, most of the steel and steel reinforced structures have been in service for decades and aging at a rapid pace. According to ASCE 2009 Infrastructure Report Card,² America''s infrastructure received an overall grade of D. For example, nationwide bridges have an average life of 43 years old.