# The Use of Non-Destructive Testing (NDT) to Detect Bed Joint Reinforcement in AAC Masonry
## 3 Experimental Campaign  
### Test Specimens  
Two masonry specimens were prepared to detect the reinforcement. Each of them contained four masonry units made of AAC, with the strength \(f_{\text{b}}\) = 4.04 N/mm\({}^{2}\) and nominal density of 600 kg/m\({}^{3}\), which were placed on thin-layer mortar of class M5. Test results for masonry units of the mortar and the masonry itself are described in the papers [10]. The specimens had a width equal to a width of a single masonry unit, a height of 970 mm and a thickness of 180 mm. The thickness of the bed joints was 3 mm in accordance with the standard EN 1996-1-1 [39]. Different types of reinforcement (Figure 1) were laid in individual joints of both specimens. The applied reinforcement included two metallic meshes, two meshes from fibreglass and two meshes from basalt fibre.  
The steel mesh with wires having a diameter of 1.2 mm and mesh size of \(12\times 12\) mm (Figure 2a) was laid in the top joint in the first test sample. The mesh wires were protected against corrosion by hot dip galvanization. The fibreglass mesh with latex protective coat and a window size \(10\times 12\) mm was used in the central joint. Its weft section was \(0.42\times 2\) mm, and a warp was composed of three fibres with the smallest section of \(2\times 0.2\times 0.4\) mm (Figure 2b). The mesh density was 2500 kg/m\({}^{3}\). A basalt mesh with a window size \(30\times 30\) mm was in the bottom joint. The weft section was \(0.8\times 3.2\) mm, and the warp was composed of four fibres with the smallest section of \(0.3\times 0.9\) mm (Figure 2c). The mesh density was 1800 kg/m\({}^{3}\).  
Additional tests were performed on the unreinforced masonry wall for comparative purposes. That wall is shown in Figure 1, behind specimens No. 1 and 2.  
Figure 1: Masonry specimens used in tests: 1—steel mesh reinforcement (size \(12\times 12\) mm), 2—fibreglass mesh reinforcement (size \(10\times 12\) mm), 3—basalt mesh reinforcement (size \(30\times 30\) mm), 4—truss-type reinforcement, 5—fibreglass mesh reinforcement (size \(5\times 5\) mm), 6—basalt mesh reinforcement (size \(8\times 8\) mm).  
The top joint in the second specimen had a truss reinforcement of EFZ 140/Z 140 type intended for masonry walls built on thin joints. That reinforcement was composed of two flat bars with a section of 1.6 \(\times\) 8 mm (design strength of strip steel/\(f_{y}\) = 685 N/mm\({}^{2}\) acc. to the code [40]) and trussing from a wire having a diameter of 1.6 mm (Figure 2d). The spacing of flat bars was 140 mm, and the reinforcement was protected against corrosion by hot dip galvanization. The fibreglass mesh (size 5 \(\times\) 5 mm) was  
Figure 2: Microscopic view of reinforcement used in tests: (**a**) steel mesh reinforcement with a diameter of 1.2 mm, (**b**) fibreglass mesh (size 10 \(\times\) 12 mm), (**c**) basalt fibre mesh (size 30 \(\times\) 30 mm), (**d**) truss-type reinforcement, (**e**) fibreglass mesh (size 5 \(\times\) 5 mm), (**f**) basalt fibre mesh (size 10 \(\times\) 10 mm).  
in the central joint. The weft section was \(0.22\times 1.5\) mm, and the warp was composed of two fibres with a smallest diameter of 0.3 mm (Figure 2e). The mesh density was 2550 kg/m\({}^{3}\). Basalt mesh size of \(10\times 10\) mm TBM Reinforcement Fiberglass Geogrid (maximum strength of 1 m of mesh determined acc. to [41], method A--testing a weft -38.7 kN/m, testing a warp--22.7 kN/m) was laid in the bottom joint in the second test sample. The mesh had a weft section of \(0.5\times 1.5\) mm, and a warp with the smallest section of \(2\times 0.3\times 0.6\) mm (Figure 2f). The basalt mesh density was 1800 kg/m\({}^{3}\).