Acoustic Emission Monitoring of Reinforced Concrete under Accelerated Corrosion

Abstract

The development of techniques capable of evaluating the deterioration of reinforced concrete structures is instrumental to the advancement of structural health monitoring (SHM) techniques and service life estimate methodologies for constructed facilities. One of the main causes of degradation is the corrosion of steel reinforcement. This process can be modeled phenomenologically, whereas laboratory tests aimed at studying durability responses are typically accelerated to provide usable results within a realistic period of time. Numerous nondestructive methods have been recently studied. Acoustic emission (AE) is emerging as a nondestructive tool to detect the onset and progression of deterioration mechanisms associated with concrete cracking. In this paper, an accelerated corrosion and continuous AE monitoring test setup is presented, providing relevant information on the characteristics of the corrosion circuit, continuous measurement procedure, selection of AE sensors, and AE parameter setting for data acquisition. The effectiveness of AE in detecting and characterizing the initiation of the corrosion process is discussed on the basis of results from small-scale, precracked RC specimens that are representative of areas near the clear cover in typical RC members. The main outcome is a new approach of AE data interpretation based on time-driven parameters

Acoustic emission-based mathematical procedure for quantification of rebar corrosion in reinforced concrete

“…REINFORCED concrete (RC) structures have the potential to be durable and capable of withstanding a variety of adverse environmental conditions 1,2 . However, failures in the RC structures still occur due to adverse effects of external or environmental agencies.…”

“…However, failures in the RC structures still occur due to adverse effects of external or environmental agencies. One of the main causes leading to degradation of RC structures is the corrosion of steel reinforcement [1][2][3] . Rebar corrosion is an electrochemical process which involves the transfer of electrically charged ions between two locations on the reinforcing bar with different potentials (anode and cathode) through the electrolyte solution provided by the pore fluid of concrete surrounding the steel 1,3 .…”

“…AE is not an electrochemical method, but by utilizing the sensitivity of the technique to the growth and initiation of micro-cracks as a consequence of corrosion reaction, the phenomenon of corrosion can be identified 6 . Studies have demonstrated that the technique can give an early warning of corrosion compared to well-established electrochemical techniques 1,[7][8][9] . Idrissi and Limam 10 showed a perfect correlation between the evolution of acoustic activity and corrosion current density.…”

“…Some of the commonly used parameters are hit-driven data (amplitude, duration, and signal strength) or time-driven data (average signal level and absolute energy) 1 . In the present study, signal strength parameter of AE was acquired and analysed to quantify corrosion.…”

“…The signal strength is often referred to as relative energy which is a measure of the amount of energy released by a specimen 11 . Research has shown that when cumulative signal strength (CSS) is plotted versus time, it will generally increase sharply at a certain time which can be correlated to damage and corrosion 1,12 . In addition, research has identified that CSS of the AE technique is a promising parameter for corrosion monitoring studies under accelerated corrosion conditions as it has a specific trend indicating active corrosion, which is similar to the curve of typical corrosion loss of steel due to sea-water immersion 13 .…”