Correlation between the mechanical behavior and the ultrasonic velocity of fiber-reinforced concrete

• Ultrasonic velocity with direct, semi-direct and indirect transmission mode.
• Correlation between consolidation level of UPFRC and ultrasonic velocity.
• Effect of metallic fibers on the ultrasonic pulse velocity.
• Correlation between ultrasonic velocity and mechanical behavior of HPFRC.

Ultrasonic velocity technique is one of the most popular non-destructive techniques used in the assessment of concrete properties. The objectives of this study are (1) to test the use of ultrasonic velocities in the non-destructive evaluation of the curing degree of fiber-reinforced concrete and (2) to find a correlation between the compressive strength, flexural strength, modulus of elasticity, and the ultrasonic velocity. This latter is measured by sensors of 50 mm diameter and 54 kHz frequency, and calculated from the phase slope. The ultrasonic velocity measurements were determined with direct, semi-direct and indirect transmission mode. This methodology is based on European standard EN 12504-4. Samples (prismatic: 10 × 10 × 40 cm and cylindrical: 16 × 32 cm) are made with different percentages (varying from 0% to 2.5%) of steel fiber.The results showed that ultrasonic velocity can be very useful to study the homogeneity and the quality of steel fiber-reinforced concrete and it is an effective way for the assessment of the consolidation level during and after the curing period (the measurements are taken at ages of 8 h and from 1 to 28 days).