Issue 46

L. Sorrentino et alii, Frattura ed Integrità Strutturale, 46 (2018) 285-294; DOI: 10.3221/IGF-ESIS.46.26 293 C ONCLUSIONS n order to increase load-carrying capacity of natural stone, an external sandwich structural laminate in composite material can be efficiently glued to a stone tile. Among the samples with core DIAB P60 and adhesive AF163-2k that with the highest value of the average maximum stress has a marble or granite thickness of 6 mm; it presents a load to bend of about 3.9 KN or 4.8 KN for marble and granite respectively that is 150% or 60% more than the corresponding sample in marble or granite only. The lightest sample, that has a marble tile of 3 mm thickness and a Hexcel Fibrelam ® core, has a weight of 11.12 Kg/m 2 that is about 3 times lower than that of the same sample of marble. The heaviest panel, that has a granite tile of 6 mm thickness and a DIAB P60 core, weights 28.14 Kg/m 2 compared to 54.54 Kg/m 2 of the same sample in granite only. Therefore, considering the load/weight ratio, that is called Performance Index PI, it can be seen that the sandwich structures have a PI from 2 to 5 times higher than that of the stone sample with the same thickness; in particular, the sandwich structure with Hexcel Fibrelam ® panel and a marble tile of 3 mm thickness has a PI equal to 138.35 N*m 2 / Kg compared to 30.64 N*m 2 / Kg of marble sample with the same thickness. Finally, it is possible to conclude that it is convenient to substitute tiles of natural stone of 20 mm or 30 mm thickness with thin stone tiles reinforced with a sandwich structural laminate in composite material. In this way it is possible to resolve some problems that are typical of stone, such as the difficulty of carriage and of assembly, the impossibility to obtain large tile (i.e. 3000 mm x 1500 mm), the excessive brittleness and so on. Moreover, it will be possible to apply the natural stone reinforced with composite sandwich panels to nautical and aerospace field, due to the significant reduction in weight, and, therefore, it will be possible to make precious the rooms of yacht and luxurious airplanes. Further testing should be done to determine the optimal number of composite fiber plies required to provide adequate mechanical proprieties. Such a determination could result in cost savings and increased ductility of the reinforced stone. In addition, the use of smaller thickness of stone should be investigated. Finally, an investigation of the effect of external composite reinforcement of stones that have curved shape should be conducted. A CKNOWLEDGEMENTS he authors are grateful to eng. Adriano for his valuable research that has given rice for this work. Special thanks to Tecnavan Interiors s.r.l. (AIDA project to bring innovation in small and medium firms of Frosinone district, Italy) for providing materials and in particular to Mr M. Fiorini and Mr S. Fini. R EFERENCES [1] Winkler, E.M (1994). Stone in architecture: properties, durability, New York, Springer-Verlag Inc. [2] Cohen, J.M. and Monteiro, P.J.M. (1991). Durability and integrity of marble cladding: a state-of-the-art review, J. Perf Constr Fac. ASCE, 5(2), pp. 113-124. DOI: 10.1061/(ASCE)0887-3828(1991)5:2(113). [3] Mays, G.C. (1985). Structural applications of adhesives in civil engineering, Mat. Sc. Techn., 1, pp. 937-943. DOI: 10.1179/mst.1985.1.11.937. [4] Neale, K.W. (2000). FRPs for structural rehabilitation: a survey of recent progress, Progress in Struc. Engin. Mat., 2(2), pp. 133-138 DOI: 10.1002/1528-2716(200004/06)2:2<133::AID-PSE16 >3.0.CO ;2-C. [5] Iyer, S., Silvaramakrishnan, C and Atmaram, S. (1989). Testing of reinforced concrete bridges for external reinforcement. In: ASCE (Eds), Structural Material: Proceedings of 7th Annual Structural Congress, New York, USA; pp. 116-122. [6] Saadatmanesh, H. and Ehsani, M.R. (1989). Application of fiber-composites in civil engineering. In: ASCE (Eds), Structural Material: Proceedings of 7th Annual Structural Congress, New York, USA, pp. 526-535. [7] Sisti R., Corradi M. and Borri A. (2016). An experimental study on the influence of composite materials used to reinforce masonry ring beams, Con. Build. Mat., 122, pp. 231-241. DOI: 10.1016/j.conbuildmat.2016.06.120. [8] Aiello, M., Micelli, F. and Valente, L. (2007). Structural Upgrading of Masonry Columns by Using Composite Reinforcements. J. Compos. Constr., 11(6), pp. 650-658. DOI: 10.1061/(ASCE)1090-0268(2007)11:6(650). [9] Kurtis, K.E. and Dharan, C.K.H. (1997). Composite fibers for external reinforcement of natural stone, J Comp. Constr., 1(3), pp. 116-119. DOI: 10.1061/(ASCE)1090-0268(1997)1:3(116) I T