Advances in test and measurement of the interface adhesion and bond strengths in coating-substrate systems, emphasising blister and bulk techniques

In this paper, recent advances in the minimum-destructive testing of the adhesion of coating-substrate systems are reviewed, focusing on key techniques such as micro- and nano-scale levels of indentation, scratching, laser-induced wave shock, as well as the blister and buckle approach. Along with adhesion failure tests, the latest and most extensive applications of the adhesion test methods in nano-, micro- and bulk-coating technology and the associated techniques to determine the minimum damage defects left on the coatings are discussed and their use reviewed

Monitoring Fracture of Steel Corroded Reinforced Concrete Members under Flexure by Acoustic Emission Technique

Acoustic emission (AE) technique is used for monitoring and evaluating the influence of corrosion on the structural behaviour of steel reinforced concrete (RC) beams under three-point flexure test. In this study, steel corrosion was accelerated by electro-chemical method utilising a direct current (DC) power supply and 5% sodium chloride (NaCl) solution. The steel corrosion that was induced into beam specimens casting were estimated at 0%, 4.55% and 32.37%, respectively, according to mass loss of steel reinforcement. Based on observations during static load test, the damage developed in the specimens could be classified into four different stages, namely, micro-cracking, first visible cracks, cracks distribution, as well as damage localization and yielding. Analysis of the AE data reveals distinguishable trends for RA value and average frequency (AF) registered for different corrosion levels, respectively. Moreover, the index of damage (ID) derived from the AE energy parameters obtained during the first stage of damage was found to be useful as an indicator for evaluating the extent of corrosion damage of RC beam specimens at initial loadings. In addition, to provide a practical application of AE toward life span estimation of corroded beam specimen, a Weibull damage function was introduced to estimate the remaining flexural capacity of the beam specimens. Based on analysis as well, it is noted that tensile fracture became more dominant with an increase in corrosion level

Influence of Material Properties of Reinforced Concrete Element on Acoustic Emission due to Corrosion

The material properties of reinforce concrete (RC) influence the corrosion process of steel rebar and subsequent cracking of concrete. This paper investigates the influence of material properties on acoustic emission (AE) due to corrosion of rebar in concrete. RC cylinders with various cover thickness to rebar diameter ratios (C/D), cement types and steel types were studied to identify their influence on cumulative signal strength (CSS) of AE technique. The result of analysis of variance (ANOVA) indicated significant effect of steel type on CSS values due to corrosion followed by cement type, whereas C/D has no significant effect

Characterisation of Al corrosion and its impact on the mechanical performance of composite cement wasteforms by the acoustic emission technique

In this study acoustic emission (AE) non-destructive method was used to evaluate the mechanical performance of cementitious wasteforms with encapsulated Al waste. AE waves generated as a result of Al corrosion in small-size blast furnace slag/ordinary Portland cement wasteforms were recorded and analysed. The basic principles of the conventional parameter-based AE approach and signal-based analysis were combined to establish a relationship between recorded AE signals and different interactions between the Al and the encapsulating cement matrix. The AE technique was shown as a potential and valuable tool for a new area of application related to monitoring and inspection of the mechanical stability of cementitious wasteforms with encapsulated metallic wastes such as Al

Use of acoustic emission signals through steel reinforcement to detect the onset of corrosion

Corrosion processes produce elastic energy waves in the form of acoustic emission (AE). For corrosion in reinforced concrete structures, AE waves are emitted beginning with the depassivation of oxide layers of reinforcing steel, the initial stage of corrosion processes. This study examines the feasibility of using AE technique to detect corrosion through steel reinforcement, which has relatively lower attenuation than concrete. Comparison of coupling AE sensors on steel and on concrete was made. Accelerated corrosion regime and two-channel multifunctional AE equipment with piezoelectric sensors were employed for laboratory experiments. The detectable distance from corrosion source to sensor was estimated via the calculation of attenuation coefficient and particle surface displacement. The analysis of source location demonstrates that surface wave is the predominant AE wave propagating in rebars with one-inch diameter. Furthermore, an important experiment was performed to compare AE measurement with half-cell potential measurement. As a result, AE was proved to be a promising tool for corrosion detection in reinforced concrete structures.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .C443. Source: Masters Abstracts International, Volume: 44-03, page: 1435. Thesis (M.A.Sc.)--University of Windsor (Canada), 2005