Currently, electromagnetic and radar methods are the most common non-destructive tests for non-destructive rebar location in structures.. Both methods have some advantages, disadvantages and limitations. This article is an attempt to describe possibilities of particular methods with emphasizing their advantages and limitations. The first stage of tests included results from tests conducted on a lintel beam made of autoclaved aerated concrete (AAC) and reinforced with small-diameter rebars and rebars placed close to each other. The second stage consisted in testing nine lightweight concrete specimens, each with three bars having a diameter of 10, 16 and 20 mm at three different space arrangements, to determine the effect of bar diameter and spacing on the measurement accuracy. The reinforcement of lintels and specimens was tested with two different electromagnetic scanners and a ground-penetrating radar (GPR) device. Received results from direct tests were compared with results from non-destructive tests (NDT). NDT tests conducted in such an element were found to perform the correct assessment of the concrete cover, and at the same time to give ambiguous results with reference to shape and number of rebars.

An increasing use of non-metallic reinforcement is problematic as it has to be detected at the stage of accepting construction works, or later when expert opinions are prepared for the building. In contrast to metallic reinforcement, location of this type of reinforcement is difficult using non-destructive techniques. Small diameters of rebars and their location in a tested element were troublesome. This article describes an attempt to locate non-metallic reinforcement in a concrete element and the masonry. Tests were performed using an ultrasonic tomograph and GPR with a broad range of frequencies.

Semi-destructive and non-destructive techniques are not commonly used for masonry as they are complex and difficult to perform. This paper describes validation of the following methods: semi-destructive and non-destructive, ultrasonic technique for autoclaved aerated concrete (AAC). The research subject was the compressive strength of AAC test elements with declared various density classes of: 400, 500, 600 and 700 (kg/m3) and various moisture levels. Empirical data including the shape and size of specimens, were established from tests on 494 cylindrical and cuboid specimens, and standard cube specimens 100×100×100 mm using the general relationship for standard concrete (Neville’s curve). The effect of moisture on AAC was taken into account while determining the strength fBw for 127 standard specimens tested at different levels of water content (w = 100%, 67%, 33% 23% and 10%). Defined empirical relations can be used to correct the compressive strength of dry specimens. For 91 specimens 100×100×100 mm, the P-wave velocity cp was tested with the transmission method using using the ultrasonic pulse velocity method with exponential transducers. The curve (fBw – cp) for determining the compressive strength of AAC elements with any moisture level (fBw) was established.