1 Non Destructive Evaluation of Concrete Structures
Non Destructive Testing/Evaluation (NDE) are means or techniques to gain the required structural and other evaluation properties of the structure without inducing damage to the structure/structural component under consideration.
Concrete is, because of its versatility, comparative cheapness and energy efficiency, of great and increasing importance for all types of construction throughout the world. Concrete structures can be durable and long lasting but to be so, due consideration needs to be given at the design stage to the effect that the environment to which the structure will be exposed will have on the concrete.
Initially, concrete was regarded as having an inherently high durability, but more recent experiences have shown that this is not necessarily the case unless durability design forms an integral part of the design and construction process. To ensure this Non-destructive evaluation of concrete is becoming popular nowadays so as to determine acceptance criteria for given requirement.
2 Importance of Non Destructive Testing (NDT)
Importance of Non Destructing Testing is as follows :-
- The important reason for popularity of NDT methods is that they offer a way to investigate structures and materials without causing them damage. In simple words, whatever is being tested/evaluated can remain intact, allowing it to preserve its structural integrity and function.
- NDT gives a way to determine whether or not the structure is capable of transferring/carrying the intended loads safely. Also they provide a measure of wear and tear of existing structure for proper strength evaluation.
- Similar to improvements on safety, NDT can also be used to improve reliability, allowing structures to be tested while they are being put through their paces, highlighting areas of weaknesses that would benefit from retrofitting/strengthening.
3 Non Destructive Testing Methods
A number of non-destructive evaluation (NDE) tests for concrete members are available to determine in-situ strength and quality of concrete. Some of these tests are very useful in assessment of damage to RCC structures subjected to corrosion, chemical attack, and fire and due to other reasons.
The term ‘non destructive’ is used to indicate that it does not impair the intended performance of the structural member being tested/investigated. The non destructive evaluation have been broadly classified under two broad categories viz ‘in-situ field test’ and ‘laboratory test’.
As per CPWD Repair & Rehab Hanbook the Non Destructive Methods for Concrete Structures can be broadly classified into following categories depending on the purpose of test-
3.1 InSitu Concrete Strength
- Rebound Hammer Test – It is a qualitative field test method to measure surface hardness of concrete.
- Ultrasonic Pulse Velocity Test – A qualitative field test by measurement of Ultrasonic Pulse Velocity (UPV).
- Windsor Probe – A qualitative field test for assessment of near surface strength of concrete.
- Capo/Pull Out Test – A qualitative field test for assessment of near surface strength of concrete.
- Core Cutting Test – It is a partial destructive test to determine the strength of concrete.
- Load Test – A field test for assessing the load carrying capacity within the limits of elastic deformations.
3.2 Chemical Attack
- Carbonation Test – A field/lab test for assessment of pH of concrete and depth of carbonation.
- Chloride Test – A field/lab Test for assessment of total water/acid soluble chloride contents.
- Sulphate Test – A Lab Test for assessment of total acid/water soluble sulphate contents of concrete.
3.3 Corrosion Potential Assessment
- Cover-Meter / Profo-meter – A field method for measuring thickness of cover concrete, reinforcement diameter & spacing.
- Half Cell Method – A field method for Measuring/ plotting corrosion potential for assessing probability of corrosion
- Resistivity Meter – A field method for assessing electrical resistivity of concrete to determine its corrosion resistance
- Permeability Test (Water & Air) – A field/Lab method for assessment of in-situ permeability of concrete due to water and air.
3.4 Fire Damage Assessment
- Thermo-Gravimetric Analysis (TGA) – A laboratory test for assessment of temperature range to which concrete was subjected to during fire hazard.
- Differential Thermal Analysis (DTA) – A laboratory Test for assessment of qualitative & quantitative composition of sample of concrete.
- X-ray Diffraction (XRD) – To determine the extent of deterioration in concrete subjected to fire.
3.5 Structural Integrity/Soundness Assessment
- Ultrasonic Pulse Velocity Test – A field method for determination of discontinuities, cracks and depth of cracks
- Radiography – For taking photographs showing details of inside of a concrete member, where other NDE methods are not suitable
- Impact Echo Test – A field/laboratory test method to detect hidden damage and its extent.
4 References
- CPWD Repair & Rehab Hanbook
- ‘Non-Destructive Evaluation of Reinforced Concrete Structures‘ by Christiane Maierhofer, Hans-Wolf Reinhardt, Gerd Dobmann, Woodheah Publishing Limited
Related Posts
Selection of Mortar
It is a well known fact 'A Chain is As Strong As The Weakest Link'....
Read More
Non Destructive Evaluation of Concrete Structures
Non Destructive Testing/Evaluation (NDE) are means or techniques to gain the required structural and other...
Read More
Qᥙalitу articles or revіews is the secret to interest the users to pay a
visit the wеb site, that’s what this sitｅ is providing.
I got thiѕ web site from my pal who told me on the topic of this
ѡeb site and at the moment this time I am browsing this site and reading very informаtive articles at thіs place.