Accuracy of Eddy-Current and Radar Methods Used in Reinforcement Detection

Abstract

This article presents results from non-destructive testing (NDT) that referred to the location and diameter or rebars in beam and slab members. The aim of paper was to demonstrate that the accuracy and deviations of the NDT methods could be higher than the allowable execution or standard deviations. Tests were conducted on autoclaved aerated concrete beam and nine specimens that were specially prepared from lightweight concrete. The most advanced instruments that were available on the market were used to perform tests. They included two electromagnetic scanners and one ground penetrating radar (GPR). The testing equipment was used to analyse how the rebar (cover) location affected the detection of their diameters and how their mutual spacing influenced the detected quantity of rebars. The considerations included the impact of rebar depth on cover measurements and the spread of obtained results. Tests indicated that the measurement error was clearly greater when the rebars were located at very low or high depths. It could lead to the improper interpretation of test results, and consequently to the incorrect estimation of the structure safety based on the design resistance analysis. Electromagnetic and radar devices were unreliable while detecting the reinforcement of small (8 and 10 mm) diameters at close spacing (up to 20 mm) and of large (20 mm) diameters at a close spacing and greater depths. Recommendations for practical applications were developed to facilitate the evaluation of a structure.

Use of TLS (LiDAR) for Building Diagnostics with the Example of a Historic Building in Karlino

“…The majority of analyses of existing structures are based on visual inspection, searching for visible cracks on the walls or slabs and others [1][2][3][4]. In some cases, special equipment is used, including sclerometers, ultrasonic emitter, radar or other non-destructing material testing methods [5][6][7][8]. Less popular are high-precision measuring techniques used only in case of uneven settling or extreme cases (excessive deflections of slabs).…”

Ultrasonic Pulse Velocity—Compressive Strength Relationship for Portland Cement Mortars Cured at Different Conditions

“…It is increasingly being used to estimate some microstructural [4][5][6][7][8] and mechanical [9,10] properties of cement-based materials. Non-destructive testing using ultrasound (NDT-UPV) has been also used in monitoring of setting and strength development of ultra-high-performance concrete [11], monitoring of mortar and concrete hardening [12,13], and detection of rebars in concrete [14,15].…”

Non-Destructive Testing of Materials in Civil Engineering

“…Article [23] presents results from non-destructive testing (NDT) that referred to the location and diameter or rebars in beam and slab members. The aim of this paper was to demonstrate that the accuracy and deviations of the NDT methods could be higher than the allowable execution or standard deviations.…”