PSI - Issue 64

Kevin Isaac Escobar et al. / Procedia Structural Integrity 64 (2024) 1476–1483 Kevin Isaac Escobar / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Nowadays, numerous infrastructures and buildings are reaching the end of their service life. Climate change can contribute to intensify this situation by increasing certain types of loads and corrosion risks. Fibre reinforced polymers (FRP) have been a popular material for retrofitting and strengthening damaged structures during the past few decades. However, poor performance at elevated temperatures and possible premature debonding are some of the disadvantages observed in this technique, primarily due to the use of organic matrices (Ferrier et al. 2016; Raoof and Bournas 2017; Tetta and Bournas 2016). As a result, researchers have proposed to replace polymeric matrices with inorganic materials like cementitious or lime-based mortars. Additionally, the continuous fibre sheets are substituted by an open mesh arrangement to facilitate the penetration of the mortar grains. This new composite is commonly known as textile reinforced mortar (TRM), but it is also identified as fabric reinforced cementitious matric (FRCM) or textile reinforced concrete (TRC) (Donnini and Corinaldesi 2017; Koutas et al. 2019; Rawat et al. 2022). Tensile testing of TRM is crucial to characterize the characteristic axial stress-strain behaviour of this composite material. The strain-stress curve of TRM is typically be divided into three main phases. Phase I is characterized by an elastic linear behaviour until the first crack within the matrix occurs, marking the end of this phase. Phase II is distinguished by the appearance of new cracks across the matrix as the applied load increases and stresses are distributed along the length of the specimen. Phase III begins when no more cracks form and pre-existing cracks widen until textile rupture. Uniaxial tensile tests are typically performed using two different methods to attach TRM coupons: a clevis grip (AC434 2016) or a clamping configuration (RILEM Technical Committee 232-TDT et al. 2016). Previous studies have shown that the testing setup may have a strong influence on the post cracking behaviour of the composite (D’Antino et al. 2023) . Coating the textile has shown to improve the performance of the TRM systems by helping the textile to reach its full potential and enhance its bond to the matrix (Signorini et al. 2018). Another important mechanical characteristic of TRM is the bond behaviour between the composite and the underlying substrate. The bond between TRM and concrete is usually analysed by conducting single-lap or double lap shear tests (Sneed et al. 2015). Common failure modes identified in bond tests include textile rupture, debonding with cohesive failure in the substrate, debonding of the TRM at the substrate-mortar interface, debonding at the textile mortar interface, and fibre slipping through the matrix. Experimental results on concrete and brick masonry substrates have shown that the predominant failure mode in TRM composites is debonding at the interface between the textile and matrix (D’Ambrisi et al. 2012) . This paper presents an experimental study on the tensile and bond responses of different TRM systems made of carbon or basalt fibres, along with different types of cementitious mortars. In this work, direct tensile tests were carried out considering both the clevis and clamping gripping methods. Bond behaviour was investigated by means of single lap shear tests.

Nomenclature A f

cross sectional area of the fibers elasticity modulus of the fibers maximum load attained in the test

E f

P max

s fu ε 1 ε 2

slippage of the fibers at the maximum load strain of TRM when first crack occurs during tensile test

maximum strain of the TRM composites

ε f

maximum strain of the fibers

σ 1

stress in the textile when first crack occurs during tensile test

σ 1m

cracking stress of the mortar in tensile test maximum stress of the textile in TRM maximum tensile strength of the fibers flexural strength of the TRM matrix ultimate stress of the fibers during bond test compressive strength of mortar or concrete

σ 2 σ f

σ flm σ fu

σ c