Characterization of FRCM- and FRP-Masonry Bond Behavior

Abstract

Composites made of fibers embedded in organic or inorganic matrices are efficient systems for reinforcing historical masonry structures to provide strength and ductility with a negligible mass increment. As it is well known, the structural performance of the composites mainly relies on their adhesion to the substrate. There are different methods to test the adhesion of the composite to the substrate: in laboratory direct shear test is the most commonly employed, while on-site the bond between the reinforcement and the substrate is checked by the pull-off test. In this paper, the adhesion of different composites to the same substrate made of fired-clay bricks is investigated by both the shear test and the pull-off test to qualitatively assess the difference in the two methods. Additionally, to investigate whether the bond is affected by the presence of water in the pores, half of the specimens were tested in water saturated conditions. Three different types of matrix (based on epoxy resin, natural hydraulic lime and Portland cement) were used for the composite matrix, without changing the geometry, the type of masonry substrate and the fibers (galvanized steel cords).

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References

[1] Babatunde, S.A. Review of strengthening techniques for masonry using fiber reinforced polymers. Compos Struct (2017) 161: 246-255.

[2] Di Tommaso, A., Focacci, F. and Micelli, F. Strengthening historical masonry with FRP or FRCM: Trends in design approach. Key Engineering Materials (2017) 747: 166-173.

[3] Sneed, L.H., D’Antino, T., Carloni, C. and Pellegrino, C. A comparison of the bond behavior of PBO-FRCM composites determined by single-lap and double lap shear tests. Cement Concrete Comp (2015) 64: 37-48.

[4] CNT-DT 215. Istruzioni per la Progettazione, l’Esecuzione ed il Controllo di Interventi di Consolidamento Statico mediante l’utilizzo di Compositi Fibrorinforzati a matrice inorganica, (2018).

[5] Franzoni, E., Gentilini, C., Santandrea, M. and Carloni, C. Effects of rising damp and salt crystallization cycles in FRCM-masonry interfacial debonding: Towards an accelerated laboratory test method. Constr Build Mater (2018) 175: 225-238.

[6] Gentilini, C., Franzoni, E., Santandrea, M. and Carloni, C. Salt-induced deterioration on FRP-Brick masonry bond. In: R. Aguilar et al. (Eds.): Structural Analysis of Historical Constructions, RILEM Bookseries 18 (2019), pp. 1914-1921.

[7] Franzoni, E., Santandrea, M., Gentilini, C., Fregni, A. and Carloni, C. The role of mortar matrix in the bond behavior and salt crystallization resistance of FRCM applied to masonry. Constr Build Mater (2019) 209: 592-605.

[8] Ghaemi Mahdi, Di Tommaso Angelo, Gentilini Cristina. An Experimental Investigation on Pull-Off Tests Conducted on FRP Composites Applied to Brick Units. Key Engineering Materials, 817 KEM, pp. 421-426 (2019).

[9] Technical datasheet of GeoCalce® Fino (Kerakoll S.p.A., Italy).

[10] EN 998-2. Specification for mortar for masonry – Part 2: Masonry mortar (2016).

[11] Technical datasheet of GeoLite® (Kerakoll S.p.A., Italy).

[12] UNI EN 12190. Prodotti e sistemi per la protezione e la riparazione delle strutture di calcestruzzo - Metodi di prova - Determinazione della resistenza a compressione delle malte da riparazione (2000).

[13] UNI EN 1542. Prodotti e sistemi per la protezione e la riparazione delle strutture di calcestruzzo - Metodi di prova - Misurazione dell'aderenza per trazione diretta (2000).

[14] UNI EN 459-1. Calci da costruzione - Parte 1: Definizioni, specifiche e criteri di conformità (2015).

[15] Franzoni, E., Gentilini, C., Santandrea, M., Zanotto, S. and Carloni, C. Durability of steel FRCM-masonry joints: Effect of water and salt crystallization. Mater Struct (2017) 50: Article N. 201.

[16] Technical datasheet of GeoLite® Gel (Kerakoll S.p.A., Italy).