Acoustic Emission Historic Index and Frequency Spectrum of Reinforced Concrete under Accelerated Corrosion

Abstract

The main cause of degradation for reinforced concrete (RC) structures is the corrosion of the steel reinforcement. Laboratory tests aimed at studying durability are typically accelerated to provide usable results within a reasonable period of time, and well-established electrochemical techniques are used for the assessment of corrosion. However, because these techniques are not suitable for continuous monitoring and are often intrusive, nondestructive testing (NDT) techniques are also suitable for monitoring. Acoustic emission (AE) is one of the NDT techniques used to detect the onset and progression of corrosion. This paper presents an accelerated corrosion test setup and AE monitoring methodology based on the historic index, H(t), for laboratory experiments on RC specimens. Accelerated corrosion is attained by increasing the capillarity suction of RC exposed to chlorides. The frequency spectrum of the AE signals before and after the initiation of corrosion is investigated to isolate the frequency components associated with corrosion. It is shown that the AE signals generated by early corrosion excite a well-defined narrow band of the frequency spectrum

Acoustic Emissions analysis of a four-point bending test on a Reinforced Concrete beam

“…In the final stages of the test CMA and LMA reach similar values, meaning that the historic index is approaching unity. This trend was also observed in [19] in a corrosion test.…”

“…Generally, it is assumed that 1-C 3 =C 1 /C 2 . In [19,31] the values C 3 =0.8 and C 1 =200 are suggested (thus implying C 2 =1000), with the rationale that the numerator should be the average signal strength of the last 20% or 200 hits, whichever is smaller. Given the low number of events recorded for the test setup described in this work, it was chosen to evaluate K considering C 3 =0.8 and C 1 =65, hence C 2 =325.…”

“…The approach of linking AE experimental data to numerical simulations seems interesting, and quite unexplored at this stage; 3. Historic and severity indices [19,20]; 4. The use of relaxation ratio, which measure the release of AE energy during unloading [21]; 5.…”

Acoustic emission monitoring of early corrosion in prestressed concrete piles

“…Extensive research on the feasibility of using AE to monitor corrosion in RC has been reported in the literature (e.g., Refs. [14][15][16][17][18]). However, corrosion of multiwire steel strands in PC may accrue from fundamentally different mechanisms such as stress corrosion cracking and crevice corrosion [8] at the wire impingement sites, potentially leading to more rapid deterioration.…”

Identification of Reinforcement Corrosion in Large-Scale RC Beams with Acoustic Emission Sensing

“…Nonetheless, this method is based on assuming uniform corrosion of the reinforcing steel, which may contradict with the actual corrosion process in existing structures [13]. It should also be mentioned that, the previously mentioned NDT methods are both not suitable for real-time monitoring and are typically intrusive [14].…”