PSI - Issue 64

Maher AL-Hawarneh et al. / Procedia Structural Integrity 64 (2024) 1103–1110 Maher AL-Hawarneh,Moustafa Mansour, Ahmad Rteil/ Structural Integrity Procedia 00 (2019) 000 – 000

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fibres (fabric) embedded in a cementitious mortar (matrix). FRCM increases the members’ capacity by transferring the forces from the concrete to the highly resistant fibres through the achieved bond between the FRCM and the surface of the member. The textiles implemented are high performance fabrics and can vary widely in pattern as well as mechanical properties depending on the application. Typical materials considered are carbon, basalt, glass, aramid and polyphenylene benzobisoxazole (PBO) that are known for having high strength-to-weight ratio, reduced manufacturing costs, improved fatigue and applicability due to their composite nature (Yao et al. 2016). Furthermore, the spacing, grid pattern and thickness can change based on application and design (Nanni 2013). The mortar utilized for FRCM is important since it transfers the applied load to the strong textile if it has impregnated and adequately bonded to the substrate. There are some general requirements for the mortar matrix, namely, it should be non shrinkable, highly workable, high viscosity, low rate of workability loss and sufficient shear strength to avoid premature debonding (Williams et al. 2015). FRCM has been proposed as a strengthening system for RC components as it overcomes some of the drawbacks associated with other materials and provides additional benefits such as vapour permeability, enhanced chemical compatibility, and fire protection with concrete and masonry structures (Bencardino et al. 2018, Younis and Ebead 2018, Awani et al. 2015). As FRCM is a new material, there are limited studies reported in the literature about the effectiveness of FRCM in confining concrete. Some studies reported investigated the confinement of concrete with FRCM jackets both for plain (Micelli et al. 2021, Adheem et al. 2021) and reinforced concrete (RC) members (Faleschini et al 2020, Ombres and Verre 2021) under axial and horizontal loading (Zanini et al.2020, Toska et al. 2022). This paper presents the experimental results of compressive strength and ductility of concrete cylindrical specimens wrapped with Carbon FRCM. 2. Experimental program 2.1. Test Matrix Standard concrete cylinders 100 mm in diameter x 200 mm long as per CSA A23.2-9C (CSA A23.1/A23.2-19 2019) were used as test specimens. All specimens were tested under axial monotonic compressive loading. The variables investigated in this study included the unconfined concrete strength (30 MPa or 55 MPa), fibres’ direction (uni-directional or bi-directional), and number of layers (1 layer or 2 layers). Accordingly, the specimens were divided into 8 groups as shown in Table 1. Each configuration had 3 replicates. The specimens were labelled “ X-Y-Z#A ” , where X indicates the nominal unconfined concrete strength (30 MPa and 55 MPa), Y shows the number of FRCM layers (1 or 2 layers), Z indicates the fibre direction used (U = uni-directional and B = bi-directional) and A the specimen repeat number (1, 2 or 3).

Table 1. Specimen’s test matrix Specimen Variant

Concrete Grade

Number of FRCM layers

FRCM System

30-0

30 30 30 30 55 55 55 55

-

-

30-1-U 30-1-B 30-2-U 55-1-U 55-1-B 55-2-U 55-0

1 1 2 1 1 2 -

U B U U B U -

2.2 Materials The two concrete grades were designed to have a compressive strength of 30 MPa and 55 MPa. The 30 MPa and 55 MPa mixes had a water-cement ratio of 0.56 and 0.32 and cement content of 388 kg/m 3 and 413 kg/m 3 , respectively. A commercially available FRCM system (fibre and mortar) was used with two types of fabrics. The uni-directional