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

1482

7

Fig. 6. Representative bond-slip curves of TRM using mortar with glass fibres, (a) carbon, and (b) basalt textile.

The TRM strips comprising basalt fibres coated with acrylic resin showed similar behaviour in all different bonded lengths, with textile rupture out of the matrix portion. As the bonded length increased, there was a progressive increase in the maximum load and its corresponding slip, indicating that stress transfer to the matrix was improved (see Fig. 6(b)). Prior to reaching the maximum load, the stress-slip curve exhibited a hardening behaviour. Subsequently, the load dropped to zero while the slip continues to slightly increase. When fibre rupture did not happen concurrently in all yarns after attaining the maximum strength, fluctuations in the load with a tendency to decrease were observed as individual yarns fail. Similar fluctuations, but in smaller numbers and with a tendency to increase, were produced in some specimens before reaching the maximum load if slippage did not occur simultaneously in all bundles.

Table 4. Bond tests average results of different TRM configurations

Specimen

Concrete batch

s fu (mm) [CoV] 0.70 [147.5%] 0.80 [123.0%] 0.46[121.4%] 1.00[117.5%] 0.40 [96.1%] 1.30 [75.0%] 0.70 [47.7%] 0.58 [65.8%]

σ fu (N/mm

2 ) [CoV]

P max (kN) [CoV]

Failure mode

CR1 CR1 CR1 CR1 CR1 CR2 CR2 CR2

CL_150_60_P3 CL_200_60_P2 CL_300_60_P2 CL_400_60_P2 CL_450_60_P3 BA_200_60_P4 BA_300_60_P4 BA_400_60_P4

1293 [10.6%] 1103 [6.9%] 1184 [7.7%] 1183 [8.8%] 1935 [9.2%] 866 [1.2%] 980 [18.5%] 1272 [22.3%]

4.27 [10.6%] 3.64 [6.9%] 3.91 [7.7%] 3.90 [8.8%] 6.39 [9.2%] 2.02 [1.2%] 2.29 [18.5%] 2.97 [22.3%]

S S

S/FR S/FR S/FR S/FR S/FR S/FR

Note: S = slippage between the textile and the mortar, FR = fibers rupture

4. Conclusions The behaviour of TRM composites with carbon and basalt fibre along with three types of mortar was studied. Coating with latex and epoxy resins was investigated with carbon textile, while a single type of coating with acrylic resin was considered for basalt fibres. A conventional cementitious mortar, a mortar with short glass fibres in its composition, and a mortar with synthetic fibres were employed. Uniaxial tensile tests were conducted using clevis grip and clamping methods. Bond performance was studied using a single-lap shear configuration. The following conclusions could be drawn based on the tests results: - The way to attach the specimens in the tensile tests influenced the crack pattern in the TRM. More cracks were discovered utilizing the clevis grip setup, allowing the coupons to attain more strain. Nevertheless, the maximum strength of the composites was not affected by the method selected for basalt fibres. For carbon textile impregnated with epoxy resin, the clamping method showed a similar response to the clevis grip method, however, the fibre tensile strength was not achieved due to slippage between the textile and the matrix. - Carbon textile impregnated with epoxy resin exhibited superior performance over carbon coated with latex resin, showing higher maximum strength and strain capabilities. The ability of the latex resin to bond the carbon filaments and distribute stresses decrease with increasing load, leading to slippage between the textile and the matrix, as well as telescopic failure. Acrylic resin in the case of basalt fibres was shown to be sufficient to promote bonding between filaments as well as between the matrix and textile. - A bonded length of 300 mm was found to be sufficient to prevent full slippage of the textile in the matrix, employing