Nondestructive testing or Non-destructive testing (NDT) is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage. Because NDT does not permanently alter the article being inspected, it is a highly valuable technique that can save both money and time in product evaluation, troubleshooting, and research. Although there can be no direct measurement of the strength properties of structural concrete for the simple reason that strength determination involves destructive stresses, these depend on the fact that certain physical properties of concrete can be related to strength and can be measured by non-destructive methods. Such properties include hardness, resistance to penetration by projectiles, rebound capacity and ability to transmit ultrasonic pulses and X- and Y-rays. The NDT methods are cost effective.

1. Non Destructive Testing
ABDUL AZEEM, 1603-147-41-007
DECCAN COLLEGE OF ENGINEERING AND TECHNOLOGY

2. Introduction
 Nondestructive testing or Non-destructive testing (NDT) is a wide group of analysis
techniques used in science and industry to evaluate the properties of a material,
component or system without causing damage.
 Because NDT does not permanently alter the article being inspected, it is a highly
valuable technique that can save both money and time in product evaluation,
troubleshooting, and research.
 Although there can be no direct measurement of the strength properties of structural
concrete for the simple reason that strength determination involves destructive stresses,
these depend on the fact that certain physical properties of concrete can be related to
strength and can be measured by non-destructive methods.
 Such properties include hardness, resistance to penetration by projectiles, rebound
capacity and ability to transmit ultrasonic pulses and X- and Y-rays.
 The NDT methods are cost effective.

3. Various non-destructive methods of
testing
 Rebound test: To estimate strength and hardness of the concrete in the
cover region (IS: 13311 Part II)
 Penetration and pull out techniques: These include the use of the Simbi
hammer, Split pins. The Windsor probe, and pullout test. These measure the
penetration and pullout resistance of concrete and for strength
estimations.
 Dynamic or vibration tests: These include resonant frequency and
mechanical sonic and ultrasonic pulse velocity methods. These are used
to evaluate durability and uniformity of concrete and to estimate its
strength and elastic properties.

4. Various non-destructive methods of
testing
 Radioactive and nuclear methods: These include the X-ray and Gamma-
ray penetration tests for measurement of density and thickness of
concrete. Also, the neutron scattering and neutron activation methods
are used for moisture and cement content determination.
 Magnetic and electrical methods: Magnetic methods are used to
determine the reinforcement in concrete, whereas the electrical methods
are used to measure moisture content and thickness of concrete.
 Acoustic emission techniques: These are used to study the initiation and
growth of cracks in concrete.
 Surface hardness methods

5. Rebound Hammer
 OBJECTIVES
― To assess quality of the concrete in relation to the standard requirements
― To estimate compressive strength of concrete with the help of suitable
correlations between rebound index & compressive strength
― To delineate regions of poor quality or deteriorated concrete in a structure
― To assess quality of one element of the concrete in relation to another

9. Factors affecting test results
 Type of cement
 Type of aggregate
 Surface and internal moisture condition
 Carbonation of concrete surface
 Age of concrete

10. Ultrasonic Pulse Velocity test
 OBJECTIVES
― To assess uniformity and homogeneity of concrete
― To assess quality of concrete in relation to standard requirements
― Detection of the presence & approximate extent of cracks, voids & other
imperfection in concrete
― Measurement of changes occurring with time in the properties of the
concrete
― Correlation of pulse velocity & strength as a measure of concrete quality

11. Techniques for measuring pulse
velocity through concrete
 Direct transmission
 Semi direct transmission
 Surface transmission

12. Estimation of strength of concrete

14. Factors affecting test results
 Smoothness of contact surface under test
 Influence of path length on pulse velocity
 Temperature of concrete
 Moisture condition of concrete
 Presence of reinforcing steel

15. Accuracy of measurement
 The ultrasonic concrete tester measures the transit time through small
specimens with the accuracy of 0.1 microseconds
 The accuracy of measurement for the soniscope is of the order of 0.5
microseconds
 Thus, the former instrument is suited for laboratory conditions, whereas the
latter is best suited for field investigations where path lengths are longer.

16. Applications
 Establishing uniformity of concrete
 Establishing acceptance criteria
 Determination of pulse modulus of Elasticity
 Estimation of strength of concrete
 Determination of setting characteristics of concrete
 Studies on durability of concrete
 Pulse velocity techniques
 Measurement of deterioration of concrete due to fire exposure

17. Dye Penetrant Inspection
 Penetrant may be applied to the test component by dipping, spraying, or
brushing
 After adequate penetration time, the excess penetrant is removed, a
developer is applied.
 Developer helps to draw penetrant out of the flaw where an invisible
indication becomes visible to the inspector

18.  Section of material with a surface-
breaking crack that is not visible to the
naked eye.
 Penetrant is applied to the surface.
 Excess penetrant is removed.
 Developer is applied, rendering the
crack visible.

19. Thank you