An ultrasonic pulse velocity test is an in-situ, nondestructive test to check the quality of concrete and natural rocks. In this test, the strength and quality of concrete or rock is assessed by measuring the velocity of an ultrasonic pulse passing through a concrete structure or natural rock formation. This test is conducted by passing a pulse of ultrasonic wave through concrete to be tested and measuring the time taken by pulse to get through the structure. Higher velocities indicate good quality and continuity of the material, while slower velocities may indicate concrete with many cracks or voids.
Contents
Testing procedure
Ultrasonic testing equipment includes a pulse generation circuit, consisting of electronic circuit for generating pulses and a transducer for transforming electronic pulse into mechanical pulse having an oscillation frequency in range of 40 kHz to 50 kHz, and a pulse reception circuit that receives the signal.
The transducer, clock, oscillation circuit, and power source are assembled for use. After calibration to a standard sample of material with known properties, the transducers are placed on opposite sides of the material. Pulse velocity is measured by a simple formula:
Interpretation of results
Quality of concrete in terms of strength, homogeneity, trapped air, internal flaws, cracks, segregation, honeycombing, compaction, workmanship, and durability can be concluded from this test. The test can also be used to evaluation the effectiveness of crack repair. Ultrasonic testing is an indicative and other tests such as destructive testing must be conducted to find the structural and mechanical properties of the material.
Regulation and standards
A procedure for ultrasonic testing is outlined in ASTM C597 - 09.
In India, ultrasonic testing is conducted according to IS 13311-1992. This test indicates the quality of workmanship and to find the cracks and defects in concrete.
Usage
This test is recommended in some of testing done by the Indian government to certify and check construction of residential buildings. http://tbk.vcp.ir/page-Ultrasonic-26407.html