A Methodology Based on Pulse-Velocity Measurements to Quantify the Chemical Degradation Levels in Thin Mortar Specimens

Abstract

In this research, ultrasonic pulse echo measurements are used to quantify through thickness chemical degradation in thin mortar specimens. The degradation level is predicted using the time of travel of the acoustic wave through the thickness of the structure. The front and back wall interaction reflections are used to obtain additional information from very early stage degradation. The pulse-velocity of sound waves as a function of the thickness of the layers within the structure is described. With knowledge of the pulse-velocity in pristine and fully degraded conditions, it is possible to determine the complete range of degradation length over the layer thickness. The method is applicable for leaching of calcium and acidic attack. The acoustic measurements were verified with destructive testing. The correlation between the acoustic and non-acoustic experiments agree with the described pulse-velocity and degraded depth function. The method based on ultrasonic measurements can be implemented in other thin-layered structures.

CT Scans of Asbestos Cement Pipes as a Reference for Condition Assessment of Water Mains

“…As such, CT is able to map degradation throughout AC pipes with a level of detail that is unmatched not only in terms of the accuracy with which it differentiates between degraded and undegraded materials, but also in terms of the large amount of information that is gained from scanning the complete pipe, as was previously shown in [15]. Especially the latter point adds an additional dimension to the measured degradation as compared to the line profiles that are typically obtained with staining techniques and more sophisticated sensors that are used in the field [1,[5][6][7][8]16].…”

“…Internationally, several promising avenues of measurement based on either acoustic or electromagnetic wave reflection have been developed [1,2], some of which have the potential for defect detection in metallic pipes as well [3,4]. Specific implementations have been piloted in The Netherlands since the early 2000s, such as a repurposing of ground penetrating radar [5][6][7] and pulse echo ultrasound [8]. Validation of these non-destructive techniques has so far mainly depended on cost-intensive and destructive experiments, such as phenolphthalein staining of core drilled samples on a lab scale.…”

Neural-Network-Based Ultrasonic Inspection of Offshore Coated Concrete Specimens

“…Until now, there have been few studies on the detection of the debonded section of the coating layer applied to the concrete structure in water immersion tests. Recent research has been based on the following methods: high-frequency wave echo decomposition [39], reflection coefficient theory [40,41], pulse-velocity-based methods [42,43], wave attenuation [44,45], the data fusion technique [46], the multifrequency method [47], and time-based parameters [48].…”