Abstract
Adoption of periodic or continuous monitoring strategies to assess condition state of infrastructure elements is a vital part of service life management (SLM). NDT methods are increasingly seen as an attractive and viable strategy to support condition monitoring. Over the last 15 years, the LEME research group at UFRGS has investigated several aspects related to the use of the ultrasonic pulse velocity (UPV) method and its potential for real field applications. One of the main advances involved the development of artificial neural network (ANN) models for correlating compressive strength and UPV measurements. Another examined problem was how to deal with the large amount of raw data derived from inspection of large structures. Several studies were carried out to check different mapping techniques, as reported by Lorenzi et al. 2011. This paper relates one investigation where UPV and rebound hammer (RH) measurements were collected from a beam containing several induced defects, simulated using different materials. The results were processed using a mapping strategy, which indicated suspicious points where core extraction was undertaken. All cores taken from points derived from UPV results were found to have flaws providing evidence that this may be a suitable tool to assess concrete structures, when data is properly interpreted.
Highlights
Concrete is the most widely used construction material in the world
The present study proposes a surface mapping technique of ultrasonic pulse velocity (UPV) and rebound hammer (RH) data which may be very useful in concrete analysis
Indirect UPV measurements were taken at the four points that made up each grid cell, resulting in 6 UPV values for each face
Summary
Concrete is the most widely used construction material in the world. Preserving its integrity is paramount to achieve the desired service life. When concrete is not properly designed or when the production process is inadequately controlled, flaws and defects can be introduced very early in the material. Concrete damage may arise as scattered microcracks, due to freeze-thaw or other expansive actions or in the form of localized large cracks due to mechanical or thermal effects, which may extend for significant distances within the structure. All these flaws can affect performance and reduce strength or durability. It is important to detect and assess their importance as early as possible. That is one of the main reasons why nondestructive testing (NDT) techniques, which are capable of detecting, locating, and characterizing most types of damage, have called the attention of practicing structural engineers, as discussed by Shah et al [1]
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