Effective strain in composites as well as potential rupture and debonding of composite materials play a crucial role in predicting the strength of retrofitted reinforced concrete (RC) beams.However, only limited experimental data on these phenomena is available, mainly due to the inadequacy of traditional monitoring systems. This paper presents a comparative analysis of different instrumentation for monitoring retrofitted RC elements. In particular, the paper addresses beams retrofitted with composite materials (FRP and FRCM) and considers strain gauges (SG), fibre-optic Bragg grating (FBG) sensors, linear variable differential transformer (LVDT), digital image correlation (DIC) and acoustic emission (AE) sensors for monitoring strain, displacement, cracking and debonding. Experiments on six beams were carried out and the measured data from the monitoring devices was compared. The accuracy of DIC for strain and displacement monitoring, as well as the ability of using AE for detecting cracks and debonding, were shown to match the performance of traditional methods, with the added benefit of providing full-field and depth monitoring. This is of particular interest for compositestrengthened concrete elements in which the accurate measurements of effective strain and debonding of the composite material can lead to developing more precise design formulae.
This is the accepted version of the paper.This version of the publication may differ from the final published version. A cascaded fibre optic acoustic sensor system, using optical filter signal demodulation has been developed and its performance extensively evaluated. To undertake this under standardized conditions, the optical sensor system was evaluated using a glass plate to detect the acoustic signal, followed by an evaluation using a metal plate to identify the location of acoustic sources, when subjected to sonotrode excitation, mimicking acoustic detection in cavitation detection. Under these circumstances, a very good agreement has been reached between the outputs of the optical acoustic sensors and of the co-located PZT acoustic sensors. This work confirms the utility of these sensors -they can detect not only weak AE signals, but also enable multipoint simultaneous measurement, showing their potential for condition monitoring applications, especially in the marine sector.
Permanent repository link
The low pH of magnesium potassium phosphate (MKPC) has raised concerns over its capability to protect reinforcing steel. The passivation of mild steel in MKPC pore solutions was investigated in this study via electrochemical measurements, XPS and Raman spectroscopy. Results show that the passivity of mild steel in MKPC was comparable or even better than that in Portland cement. Although the passivity was dominated by the pH of MKPC, 2 it also increases with increasing magnesium-to-phosphate (M/P) ratios. The formation of iron phosphate in the low pH MKPC (such as M/P 7) also made additional contributions to the passivity of steel.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.