PSI - Issue 29

A. Boostani et al. / Procedia Structural Integrity 29 (2020) 79–86 Boostani et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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4.1. Three-point bending tests on gypsum-basedcomposite rods Using mortar type A2, unreinforced and glass reinforced rod samples were prepared for three bending tests. A PVC mould with a 25 mm interna l diameter was built to make the samples. Four unreinforced samples (UCR-A2) were cast by using only A2 mortar. Twelve glass fibre-reinforced composite specimens were cast using a rounded sheet to form a cylindrica l glass fibre net. Of this group, for six of them (CR1-A2) the cylinder diameter was 15 mm wide, for the remaining 6 specimens (CR2-A2) the cylinder diameter was 20 mm wide. The net was located in the centre of the mould. Three-point bending tests were carried out on these samples. The textile is an unba lanced mesh, (4.15mm in the warp direction and 3.8 mm in the wef t direction) shows a weight on surface unit equa l to 160 gram/m 2 . According to datasheet, the tensile force for length unit is > 35 N/mm. Test apparatus and test implementa tion were the same of previous experimentation. Tests results are summarized in the comparingdiagram, Figure 3, and consist of themaximum load and thedisplacement a t the maximum load. As expected, a first crack appears after loading around 200 N, equa l to the maximum load capacity of the matrix and corresponding to the maximum load of UCR specimen. A second crack occurs for both CR1 (at 500 N) and CR2 (at 600 N) ma inta ining a linear behaviour. CR2-A2 rod exhibits a better mechanica l behaviour (average va lue of load capacity equa l to 830 N). The cylindrica l shaped glass fibre net quadruples the bending capacity of UCR. The CR2-A2 was chosenas thebest composite for thestitching.

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(d) Figure4. (a) The rammed earth block, (b) the test apparatus, (c) crack pattern of the threaded stitching bar after the tes t, (d) The pull-out test, the Load-Displacement diagram 4.2. Pull-out tests on gypsum-based composite rods In order to eva luate the adhesion between the stitching rods and the rammed earth wa ll two different samples were used for the pull-out test: 1) UN-THREAD ROD, a cylindrica l shaped sample, 380 mm in height, 32 mm in