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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For basalt textile the acrylic coating was sufficient to achieve the tensile strength of the textile using conventional mortar. Using the mortar with synthetic fibres resulted in fewer cracks, and slippage between the textile and the matrix prevented it from reaching the maximum tensile strength of the textile.

Fig. 5. Strain-stress curve of TRM using basalt textile coated with acrylic resin, (a) conventional mortar, and (b) mortar with synthetic fibres.

The stress in the textile when the first crack appears in the mortar was in a range close to half the textile strength. This was identified to have an impact on the number of cracks developed. When the appearance of the first crack happens at a loading level near the maximum strength of the textile, less margin is left for crack developing. Therefore, high resistance mortars should be accompanied with a high resistance textile to develop sufficient deformation capacity of the textile.

Table 3. Tensile tests average results of different TRM configurations.

Specimen

σ 1m (N/mm

2 ) [CoV]

ε 1 (%) [CoV] 0.030 [77.9%] 0.150 [148.4%] 0.031 [81.4%] 0.093 [130.1%] 0.110 [86.5%] 0.012 [44.8%]

σ 1 (N/mm

2 ) [CoV]

ε 2 (%) [CoV] 0.78 [52.2%] 1.24 [92.3%] 1.90 [27.0%] 2.26 [8.0%] 1.58 [41.6%] 1.14 [35.3%]

σ 2 (N/mm

2 ) [CoV] P

max (kN) [CoV] 3.70 [25.9%] 4.04 [39.1%] 9.94 [18.1%]

CL_600_60_C1 CL_600_60_P1 CE_600_60_C2 CE_600_60_Z1 BA_600_60_C3 BA_600_60_Z2

2.20 [29.0%] 2.95 [24.7%] 3.50 [15.4%] 2.35 [48.2%] 2.10 [13.4%] 4.75 [18.6%]

594 [28.1%] 826 [22.9%] 759 [13.5%] 508 [48.2%] 818 [14.5%] 921 [19.7%]

1122 [25.9%] 1224 [39.1%] 3013 [18.1%] 3392 [10.2%] 1513 [1.8%] 1322 [8.7%]

11.19 [10.2%]

3.55 [1.8%] 3.10 [8.6%]

3.2. Bond-slip relationship Average ultimate strength, along with the corresponding global slip and failure mode are reported in Table 4. The global slip is measured at the loaded end of the TRM. All single-lap shear specimens presented either slippage between the fibres and the mortar or a combination between slippage and fibre rupture. During testing, no transversal cracks in the matrix were observed, which was most likely due to the presence of short glass fibres in the mortar. As a result, the slippage measured mainly occurred at the textile to matrix interface. Although shrinkage cracks were present in some specimens at the contact matrix-substrate near the stress transfer zone, no crack propagation or widening was seen during or after testing. The interface between the matrix and the substrate did not play an important role in the selected configuration of textiles and mortar. The specimens with carbon textile coated with latex resin presented complete slippage of the fibres without rupture in all specimens with bonded length less than 200 mm. A residual frictional resistance was observed while the inner filaments of the bundles in the warp direction were extracted. Analysis over the matrix after testing showed that some outer filaments ruptured inside the mortar. The number of filaments and the spacing between yarns may have a substantial impact on the prevalence of total slippage of the textile, since a higher number of filaments in a yarn decreases the ratio between filaments in contact with the matrix and inner filaments. For bonded lengths longer than 300 mm, initial slip occurred followed by a progressive rupture of fibres. Complete and simultaneous failure of the textile outside the TRM strip was obtained using a bonded length of 450 mm. Bond-slip relations for all bonded lengths of carbon TRM are shown in Fig. 6 (a).