Tensile Behavior of FRCM Coupons under Thermal Stresses

Abstract:

Fiber Reinforced Cementitious Matrices (FRCM) represent a very efficient strengthening solution for the improvement of the structural behavior of existing masonry constructions. However, the mechanical performances of these materials could be significantly affected by different environmental conditions, such as the exposure to thermal stresses. This aspect should be properly assessed for a correct design of the strengthening interventions. The Italian Guidelines for the identification, qualification and acceptance control of FRCM systems to be used for the structural strengthening of existing constructions prescribe the execution of direct tensile tests on FRCM coupons to evaluate the behavior of these composite systems subject to thermal stress. Within this framework, the objective of the present research is to evaluate the effect of a thermal stress on the tensile behavior of three different FRCM systems, composed by steel or basalt fibers and lime-based or cement-based mortar matrix. Tensile tests are performed, for each system, on samples at ambient temperature (22°C) and on samples conditioned at 80°C for six hours, according to the indications provided by the Guidelines. The test results show that the effect of the thermal stresses is more evident in the first phases of the tests, i.e. during the elastic phase and the mortar matrix cracking phase, while it is less significant in the last phase, which is related to the fibers behavior. The tensile strength of the investigated FRCM systems is, indeed, within the limits provided by the Italian Guidelines, while the curves of the conditioned samples may deviate from the reference ones at the beginning of the tests. These findings are critically discussed within the paper.

• Periodical: Key Engineering Materials (Volume 916)
• Pages: 50-57
• DOI: https://doi.org/10.4028/p-rki9n6
• Online since: April 2022
• Authors: Francesca Ferretti*, Anna Rosa Tilocca, Andrea Incerti, Claudio Mazzotti, Marco Savoia
• Keywords: Experimental Tests, FRCM, Tensile Behaviour, Thermal Stress

References

[1] C. Papanicolaou, T. Triantafillou, M. Lekka, Externally bonded grids as strengthening and seismic retrofitting materials of masonry panels, Construction and Building Materials 25 (2011) 504–514.

DOI: 10.1016/j.conbuildmat.2010.07.018

[2] F. Parisi, I. Iovinella, A. Balsamo, N. Augenti, A. Prota, In-plane behaviour of tuff masonry strengthened with inorganic matrix–grid composites, Composites Part B: Engineering 45 (2013) 1657–1666.

DOI: 10.1016/j.compositesb.2012.09.068

[3] A. Bellini, A. Incerti, M. Bovo, C. Mazzotti, Effectiveness of FRCM Reinforcement Applied to Masonry Walls Subject to Axial Force and Out-Of-Plane Loads Evaluated by Experimental and Numerical Studies, International Journal of Architectural Heritage 12(3) (2018) 376-394.

DOI: 10.1080/15583058.2017.1323246

[4] M. Del Zoppo, M. Di Ludovico, A. Prota, Analysis of FRCM and CRM parameters for the in-plane shear strengthening of different URM types, Composites Part B: Engineering 171 (2019) 20–33.

DOI: 10.1016/j.compositesb.2019.04.020

[5] F. Ferretti, C. Mazzotti C, FRCM/SRG strengthened masonry in diagonal compression: experimental results and analytical approach proposal, Construction and Building Materials (2021) 283-122766.

DOI: 10.1016/j.conbuildmat.2021.122766

[6] F. Ceroni, G. de Felice, E. Grande, M. Malena, C. Mazzotti, F.S. Murgo, E. Sacco, M.R. Valluzzi, Analytical and numerical modeling of composite-to-brick bond, Materials and Structures 47(12) (2014) 1987-2003.

DOI: 10.1617/s11527-014-0382-8

[7] A. Bellini, M. Bovo, C. Mazzotti, Experimental and numerical evaluation of fiber-matrix interface behaviour of different FRCM systems, Composites Part B: Engineering 161 (2019) 411-426.

DOI: 10.1016/j.compositesb.2018.12.115

[8] A. Bellini, S. K. Shahreza, C. Mazzotti, Cyclic bond behavior of FRCM composites applied on masonry substrate, Composites Part B: Engineering 169 (2019) 189-199.

DOI: 10.1016/j.compositesb.2019.04.009

[9] F. Ferretti, A. Incerti, A.R. Tilocca, C. Mazzotti, In-plane shear behavior of stone masonry panels strengthened through grout injection and fiber reinforced cementitious matrices, International Journal of Architectural Heritage (2019).

DOI: 10.1080/15583058.2019.1675803

[10] A. Incerti A., F. Ferretti, C. Mazzotti, FRCM strengthening systems efficiency on the shear behavior of pre-damaged masonry panels: an experimental study, Journal of Building Pathology and Rehabilitation 4:14 (2019).

DOI: 10.1007/s41024-019-0053-9

[11] F.S. Murgo, F. Ferretti, C. Mazzotti, A discrete-cracking numerical model for the in-plane behavior of FRCM strengthened masonry panels, Bulletin of Earthquake Engineering 19 (2021), 19, 4471–4502.

DOI: 10.1007/s10518-021-01129-6

[12] J. Donnini, Durability of glass FRCM systems: Effects of different environments on mechanical properties, Composites Part B: Engineering 174 (2019) 107047.

DOI: 10.1016/j.compositesb.2019.107047

[13] F. Micelli, M.A. Aiello, Residual tensile strength of dry and impregnated reinforcement fibres after exposure to alkaline environments, Composites Part B: Engineering 159 (2019) 490-501.

DOI: 10.1016/j.compositesb.2017.03.005

[14] A. Bellini, A.R. Tilocca, I. Frana, M. Savoia, C. Mazzotti, Environmental durability of FRCM strengthening systems and comparison with dry fabrics, Proceedings of 17th IB2MaC 2020 – 17th International Brick and Block Masonry Conference, Krakow, Poland, 5-8 July (2020).

DOI: 10.1201/9781003098508-50

[15] A. Dalalbashi, B. Ghiassi, D.V. Oliveira, Aging of lime-based TRM composites under natural environmental conditions, Constr. Build. Mater. 270 (2021).

DOI: 10.1016/j.conbuildmat.2020.121853

[16] L. Ombres, A. Iorfida, S. Mazzuca, S. Verre, Bond analysis of thermally conditioned FRCM-masonry joints, Measurement 125 (2018) 509-515.

DOI: 10.1016/j.measurement.2018.05.021

[17] S.R. Maroudas, C.G. Papanicolaou, Effect of High Temperatures on the TRM-to-Masonry Bond, Key Engineering Materials 747 (2017) 533-541.

DOI: 10.4028/www.scientific.net/kem.747.533

[18] A. Iorfida, S. Candamano, F. Crea, L. Ombres, S. Verre, P. De Fazio, Bond Behaviour of FRCM Composites: Effects of High Temperature, Key Engineering Materials 817 (2019) 161-166.

DOI: 10.4028/www.scientific.net/kem.817.161

[19] Consiglio Superiore dei Lavori Pubblici, Linea Guida per la identificazione, la qualificazione ed il controllo di accettazione di compositi fibrorinforzati a matrice inorganica (FRCM) da utilizzarsi per il consolidamento strutturale di costruzioni esistenti (in italian), (2018).

DOI: 10.3221/igf-esis.12.04

[20] EN 1015-11:1999/A1:2006. Methods of test for mortar for masonry - Part 11:Determination of flexural and compressive strength of hardened mortar (2006).

DOI: 10.3403/01905442u