PSI - Issue 70

R. Ashwathi et al. / Procedia Structural Integrity 70 (2025) 183–190

188

Fig. 3. Flexural Strength of concrete The percentage increase tends to range between 6.87% and 19.85% and 3.05 and 21.87% for PFRC and SFRC showing that addition of fibres enhances tensile strength of concrete. The percentage increase tends to range between 59.54% and 70.23% emphasises the combined effect of PFRC and SFRC as shown in Fig. 3. The steel and polyester fibres incorporated in the ratio of 0.5-0.5 exhibits the highest performance among various mixes. The hybrid mix of 0.5-0.5 PFRC - SFRC of the fibre provides an enhancement in mechanical performance of the structure. Ultrasonic Pulse Velocity (UPV) Test, nondestructive testing become essential in determining the quality and structural performance of concrete without causing damage to the structure (Shi et al., 2023). The fibres in the FRC, influences the mechanical and durability properties, thereby necessitating the demand for evaluation of NDT techniques (Najm et al., 2022). It modifies the surface hardness, resistivity and wave propagation and the insights are helpful in improving the density and homogeneity of the structure (de la Cruz et al., 2022). The UPV method is one of the majorly adopted techniques in evaluating the uniformity for the quality assurance of the concrete. It evaluates the time taken for the ultrasonic pulse to travel through the concrete (Najm et al., 2022; Nematzadeh Morteza; Samadvand, Hojjat, 2021). The outcomes attained with various fibre reinforced concrete with varying proportions at different curing ages is given in Table 7 and Fig.4. 3.4 Ultrasonic Pulse Velocity Test:

Table 7. Flexural Strength of concrete

Pulse Velocity Test (m/s)

Pulse Velocity Test (m/s)

Specimen

% added

Specimen

% added

CC

0

4236.37

SFRC

0.5

4874.09

PFRC

0.25

4481.20

SFRC

0.75

4525.91

PFRC

0.5

4719.23

HFRC

0.25 - 0.75

4814.85

PFRC

0.75

4520.84

HFRC

0.50 - 0.50

5105.07

SFRC

0.25

4600.03

HFRC

0.75 - 0.25

4773.79