PSI - Issue 64

A. Alecci et al. / Procedia Structural Integrity 64 (2024) 1951–1958 Alecci et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Note: F max = maximum load, δ max = displacement referred to the maximum load, s max = slip referred to the maximum load, σ r = maximum stress, ε max = deformation referred to the maximum stress, K= tangential stiffness, μ c = kinematic ductility, μ cd = available kinematic ductility. The three FRLM systems showed a global slip behaviour characterized by four phases. The first phase showed an approximately linear-elastic behaviour (uncracked FRLM). Then the specimen stiffness decreased due to microcracks formation at the textile-matrix interface. As soon as the specimen reached the debonding load, the textile began to slip into the matrix. This phenomenon was highlighted by a sudden change in the curve slope. After the peak load was reached, a fourth phase (softening) was observed and the failure mode due to textile-matrix slip occurred. All the mortar matrices of the FRLM systems showed good bond capacity to the substrate. In fact, debonding at the matrix substrate interface never occurred. Comparing the results of the three tested FRLM systems, it can be observed that specimens assembled with Int_01 and Int_06 matrices showed maximum load and ductility higher than the Int_05 matrix. For this reason, to evaluate the effect of longer anchorage length six masonry pillars of size 55x55x315 mm 3 reinforced with FRLM systems composed of basalt mesh embedded into Int_01 and Int_06 matrices were tested subject to tensile test to ascertain the composites with the best mechanical properties. The anchorage length of 290 mm was adopted. In Figure 4, the diagrams obtained from the tests conducted on the reinforced specimens with longer anchorage lengths are overlaid on those found in the literature. The diagram highlights that the results obtained from the tests conducted on the specimens assembled with Int_01 and Int_06 matrices and basalt fibre exhibited behavior consistent with single shear tests conducted on specimens reinforced with uncoated glass fiber and cement-based matrix as seen in D'Antino et al. (2015), with coated glass fiber and cement-based matrix and with basalt fiber and cement-based matrix as ascertained by Alecci et al. (2021). On the other hand, the mechanical behavior is not very comparable, in terms of load, with the values obtained from the reinforcement systems consisting of PBO fabric combined with the cement-based matrix as seen in Focacci et al. (2017) and specimens reinforced with uncoated carbon fabric and cement-based matrix as highlighted by Raoof et al. (2016). Therefore, the obtained values are promising and need further development.

Fig. 4. Comparisons with diagrams found in the literature.

Conclusion The aim of this research is to propose a strengthening system that combines seismic improvement with energy efficiency applicable to historic buildings belonging to the historic building heritage. With a view to meeting compatibility, sustainability and reversibility requirements, the proposed composite material is characterized by an inorganic matrix based on natural hydraulic lime and reinforced with basalt fabric. The results reported in this article show that the Int_01, Int_06 and Int_10 mortars have good mechanical behavior in terms of compressive strength, flexural strength and Young's modulus values. The FRLM strengthening system with Int_06 matrix showed better behavior both in terms of energy and mechanical performance. In fact, the walls redeveloped with this reinforcement system exhibited the lowest thermal transmittance and better mechanical behavior in terms of adhesion as the anchoring length increased from 220 to 290 mm. With the exception of the reinforcement systems with cement matrix and carbon fiber and PBO, the composite proposed in this work showed good mechanical capabilities comparable to those of other commercially available composites. Therefore, this composite appears to be a promising solution to improve the thermohygrometric performance of historic envelopes, without altering their mechanical characteristics.