Development of non-destructive testing method to evaluate bond condition of reinforced concrete beam

A non-destructive ultrasonic testing method of a bond condition of a concrete beam reinforced by steel rods, comprising:

• applying, by a transmitting transducer of an ultrasonic tester, ultrasonic pulses to a concrete beam;
• receiving, by a receiving transducer, vibrational waves reflected from the steel rods at a plurality of reading locations along the concrete beam;
• measuring a transit time of the vibrational waves received at each reading location;
• determining a pulse velocity of each vibrational wave received at each reading location;
• determining a highest pulse velocity of the vibrational waves at each reading location, the highest pulse velocity at each reading location defining a first reference pulse velocity at the reading location;
• determining a peak load carrying capacity (Ppeak) of the concrete beam by
• applying a force perpendicular to a center of a length of the concrete beam;
• applying a second set of ultrasonic pulses to the concrete beam;
• measuring the highest pulse velocity at each reading location received from the second set of ultrasonic pulses;
• increasing a magnitude of the force by increments;
• measuring the highest pulse velocity at each reading location for each incremental increase in the magnitude of the force;
• and
• determining the peak load carrying capacity (Ppeak) of the concrete beam when the highest pulse velocity at one of the reading locations is less than a second reference pulse velocity, wherein the second reference pulse velocity is less than the first reference pulse velocity.

A system for non-destructive testing of a bond condition of concrete beams reinforced by steel rods, comprising:

• a transducing transmitter;
• a transducing receiver;
• an ultrasonic pulse generator configured to generate drive signals for the transducing transmitter and receive a plurality vibrational waves at the transducing receiver;
• a computing device including:
• a measurement circuit configured to record a transit time for each vibrational wave and divide a distance between the transducing transmitter and the transducing receiver by the transit time to determine a pulse velocity of each vibrational wave;
• a comparison circuit configured to identify a highest pulse velocity of the vibrational waves and compare each highest pulse velocity to a first reference pulse velocity;
• and
• a decision circuit configured to identify a compromised bond condition around a steel rod when the highest pulse velocity is less than the first reference pulse velocity;
• and
• a peak load testing device including:
• a first support configured to support a first bottom end of the concrete beam;
• a second support configured to support a second bottom end of the concrete beam;
• a force applicator configured to provide a variable force to a top center of the concrete beam;
• and
• wherein the computing device is further configured to record measurements of the pulse velocities at a plurality of reading locations for each change in the variable force and identify an amplitude of the variable force at which the highest pulse velocity is less than a second reference pulse velocity, wherein the second reference pulse velocity indicates a bond condition of cracking of the concrete around a steel rod.