PSI - Issue 64

Paula Folino et al. / Procedia Structural Integrity 64 (2024) 1452–1459 Folino et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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displacement transducers (LVDTs) with a range of ±2.5 mm, arranged in support rings. Prior to testing, the end faces of the specimens were polished using a GCTS Model RSG-200 polishing machine to ensure parallelism and flatness of opposite faces. Tests were conducted under axial displacement control at a constant speed of 0.005 mm/sec. Splitting tensile tests were conducted in accordance with ASTM C496-05. The tests were performed under displacement control at a constant speed of 0.002 mm/sec , recording the crack opening (Δ) using an LVDT (range of ±2.5 mm) on one face of the specimen, and the axial load ( P ) using the data acquisition system of the testing equipment. TPB tests on prismatic specimens were performed according to the recommendation RILEM-TC-162-TDF. Prior to testing, a 25mm deep notch was made at the central point using wet cutting. The tests were conducted under CMOD control, with an initial stage at a speed of 0.01 mm/min until 0.25mm, and then at a speed of 0.20 mm/min until the end of the test, measuring the opening of the crack mouth displacement (CMOD) with a clip gauge, Epsilon model 3541-010. In turn, a loading frame Amsler brand with one hydraulic loading jack with a load maximum capacity of 200 kN was used for performing the TPB tests on unjacketed and jacketed beams, with a span between supports of 1000 mm. The tests were conducted under load control, measuring the load using an HBM RTN 0.05 load cell with a maximum capacity of 330 kN while recording deformations at the center of the span using an LVDT Deflection Gauge. Data was recorded by connecting both instruments to an HBM QuantumX MX840B data acquisition system. 3. Experimental results 3.1. Properties in Fresh State Given the use of self-compacting concretes, the consistency was evaluated using the slump flow test and T50 test. The SCHSC exhibited a slump flow diameter of 730 mm and a T50 time of 3 sec, while the SCFRHSC showed values of 650 mm and 4 sec, respectively. 3.2. Small samples mechanical test results UC mean test results are summarized in Table 4, indicating the uniaxial compressive strength ( f' c ), maximum axial strain ( ε 0 ), and Young's modulus ( E ). ST mean test results are presented in Table 5, showing the mean peak stress for the different materials. Tensile stresses were determined using the equation f st = 2P / πDL , where D is the diameter of the specimen and L its length. Table 6 shows the TPB mean test results on notched prismatic specimens. The proportional limit stress ( f t-TPB ), and the residual stresses at CMOD values of 0.50mm, 1.50mm, and 2.50mm, as shown, were determined according to the recommendation RILEM-TC-162-TDF as f t-TPB = 3 P L / 2 b h sp 2 , where P is the axial load, b and h sp are the section width and height at the notch, respectively and L is the distance between supports.

Table 4. Uniaxial compression mean test results.

Table 5. Splitting tensile mean test results.

NSC 45.81

SCFRHSC

NSC 4.82

SCFRHSC

[MPa]

62.48 2.431 36081

[MPa]

9.45

f' c ε 0 E

f st

[‰]

- -

[MPa]

Table 6. TPB mean test results on prismatic specimens. FL

CMOD=0.50mm CMOD=1.50mm CMOD=2.50mm

f t-TPB

[MPa]

3.81

5.25

4.96

4.72

3.3. Jacketed beam tests The results of the obtained peak loads corresponding to TPB tests on unjacketed and jacketed beams are presented in Table 7 while Fig. 2 depicts the mechanical behavior represented by the load-deflection curves for each test. Curves