PSI - Issue 29

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

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Boostani et al./ Structural Integrity Procedia 00 (2019) 000 – 000

diameter, and 2) THREAD ROD, a cylindrica l shaped sample with a sort of thread to improve the bond with the earth; the dimensions of the rod were, in this case, 200 mm in height and 32 mm in diameter, not including the thread. For the reinforcement, the diameter of the glass fibre hollow cylinders measured 25 mm and the length was the same of the respective rods. For the gypsum matrix, gypsum type A2, previously studied, was used. The studied rods are designed to be built in situ: a rolled-up strip of glass fibre (as hollow cylinder) is inserted into a hole drilled in the wa ll, then a gypsummatrix is injected into the hole. Thus, bar is made of fibre-reinforcedcomposite material. The test apparatus consists of a meta l frame that locks a rammed earth block and the anchoring system of the rod to the test machine, which applies traction force by a 5 Ton Pfaff Silberblau screw jack. The apparatus a lso consists of a 5-ton Luchsinger load cell for load measurement and a displacement transducer fixed on top of the joint between the load cell and the anchoring system of the rod. The rod anchoring system is made with a steel bar glued to the rod using epoxy resin. In order to simula te the rammed wa ll, a 40x40x40 cm rammed earth block was created inside a wooden frame made with 18 mm thick wood planks, Fig. 4a . The earth, with 10 percent wa ter added to the dried soil, was mixed using a mechanica l mixer for 5 minutes and then was rammed in 8 cm layers with a 3 kg rammer. An a ir ventilated oven was used for drying the earth. Since the rods will be implemented in the wa ll with a 45-degree angle, the wooden mould was rotated by 45 degrees and the earth layers rammed horizonta lly. After the mould was removed, the earth blocks were left to dry for 8 weeks. During the pull-out tests, the load-displacement diagrams were recorded. In Figure 4d, it is possible to compare these diagrams. The result emphasizes the effectiveness of the threated system (maximum load is four times grea ter than un-threated), so the threaded composite rodwas chosen for the site intervention. 5. Closing remarks The work dea ls with the consolidation of an ancient, magnificent, building made with different and fragile materia ls. This type of intervention requires an interdisciplinary approach where safety problems must be composed with those related to safeguarding. A methodology of investiga tion that considers the request for compatibility with the origina l materia ls, a lthough centred on the structura l aspects, is proposed. This ba lance is an indispensable condition for a good result both from the safety and the conservation points of view. Here, the experimenta l activity provides a decisive contribution to the identification of the solutions. 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