Ultrasonic-Pulse Velocity
JS Building Diagnostics specializes in the use of the Ultrasonic Pulse Velocity (UPV) nondestructive evaluation technique for existing condition assessment, material property evaluation, and quality assurance testing. Based on the principles of through-transmission ultrasonics, UPV testing of structural materials applies fundamental theories of vibrating elastic mediums to measure changes in material density and elastic modulus.
Methodology
UPV testing introduces pulsed longitudinal stress waves at a surface and measures signals received from opposing or alternate faces of the test element. Stress pulses are transmitted and received using piezoelectric transducers that are acoustically coupled to the testing surfaces. Transit time and signal amplitude of a transmitted pulse are measured using a pulse velocity meter and a digital oscilloscope. Detected changes in arrival time, amplitude, and characteristics of the propagated waves can indicate corresponding differences in the internal condition of the element. Quantitative and qualitative assessments of measured signals are performed by experienced operators.
For the testing of concrete, sound regions exhibit strong signal transmittance, with nominal signal attenuation normally associated with varying path lengths through the member. The presence of internal flaws or areas of deterioration affects stress wave propagation through the member. Poor surface conditions, such as delamintations, laitance, or unsound surfaces, can also result in significant signal attenuation during testing.
Common Applications
Evaluation of the uniformity of concrete within structural members
Detection of internal flaws, such as voids, cracks, delaminations, and honeycombing in concrete members
Assessment of areas of material degradation or low-strength concrete
Estimation of the depth and severity of fire-damaged concrete
Evaluation of the effectiveness of crack repairs
Identification of anomalous regions for invasive sampling with drilled cores
Laboratory assesssment of material samples
ASTM C 597 "Standard Test Method for Pulse Velocity Through Concrete"
