The document provides information on conducting condition surveys and non-destructive evaluation of concrete structures. It discusses examining concrete to identify distress, collecting a structure's history, and assessing causes of issues like corrosion or cracking. Non-destructive tests mentioned include rebound hammer, ultrasonic pulse velocity, pullout tests, and cover meter readings to evaluate concrete strength, cracking, and rebar location without damaging the structure. The document provides detailed procedures for performing these assessments and tests.

1. CONDITION SURVEY AND NON
DESTRUCTIVE EVALUTION
AVINASH KUMAR GUPTA
CCW TRAINING INSTITUTE
NEW DELHI
07/04/2017

2. CONDITION SURVEY
• Examination of concrete
• For identifying and defining areas of distress.
• Recording history from inception to
completion and subsequent life.

3. Objective
• Identify cause of distress and sources
• Assess: extent of distress due to corrosion,
fire, earthquake, any other reason
• Asses residual strength of structure and its
rehabilitability
• Prioritize the distressed elements as per
seriousness.
• To select and plan the effective remedy.

4. Stages of condition survey
• Prioritize distressed elements according to
seriousness for repairs.
• a) Preliminary inspection
• b) Planning
• c)Visual Inspection
• d) Field and laboratory testing.

5. Preliminary inspection
• History of structure from client, owner,
occupants, General public in building,
• Note records, previous repairs history and
expenses done for the same.
• All possible data and information.
• Practical restriction in survey and safety
requirements for survey team.
• Extent and quantum of survey work
• Time required ( survey and execution )
• Advise immediate safety measures

6. Information gathering
• . Period of construction
• Construction details (drg,arch,structural )
• Exposure conditions
• Designed and present use of structure.
• Previous changes in use
• Record of structural changes if done.
• Record of 1st
occurrence of defect.
• Details of repairs carried out previously.
• Previous reports etc.
• Details from owner, photographs

7. Planning survey
• Field documents
• Plans and actual observations each room-
wise.
• Previous report , advise if any and
implementation done as per report,
• Grouping of structural elements ( external,
interior etc )
• Exposure conditions

8. Classification of damage
• Class O : No distress but cosmetic repairs
• Class 1 : Minor repairs ( superficial repairs )
• Class 2 : Medium repairs ( patch repairs )
(minor structure cracks)
• Class 3 : Principal repairs (spalling of cover
concrete,structural cracks,cracks along bars)
• Class O : Major repairs(replacement of
structural Members)

9. Grade for Assessment of the building
• Based on the inspection and observation the distress level of the
selected buildings may be categorizedas mentioned below:
• G1 – No distress observed
• G1 – Minor distress observed in few structural members, which can
be repaired under the advice of a structural engineer.
• G2 – Medium distress observed in few structural members, which
can be repaired / rehabilitated including strengthening with the
advice of a structural engineer
• G3 – Severe distress observed in some of the structural members,
which can be rehabilitated including strengthening with the advice
of a structural engineer.
• G4 – Severe distress is observed which could prove dangerous,
hence evacuation at an early date is required.

10. Visual Inspection
• Workmanship, structural serviceability, material
deterioration mechanism
• General health( structural and non structural elements)
• Preparation of estimate / bill of quantities.
• Quantify extent of distress
• Photographic record.
• Obstructions for visual inspection to be noted.
• Understanding structural system / deviations
• Leakage , seepage due to inadequate drainage system
• Types of cracks and its pattern
• Color and texture of concrete surface (chemical attack or
disintegration by way of leaching

11. Record
• Areas of high distress
• Cracks and their locations
• Excessive deflections
• Exposure conditions of various distressed areas.
• Moisture / seepage / leakages / dampness
locations.
• Abnormal vibrations in structure.
• Algae, fungus growth, trees on structure.
• Photographic record.
• Areas of immediate concern

12. Considerations for repairs strategy
• Identification of cause of problem.
• Assessment and extent of damage.
• Availability space and accessibility w.r.t.
ongoing activities in building.
• propping structural members in case of major
repairs , severely damaged elements (columns
etc ).
• Safety measures to avoid mishaps

13. Non destructive Evaluation tests
• These tests do not impair performance of the
member, They are field or laboratory tests.
• Put under five categories based on purpose,
In-situ-Concrete strength
Chemical attack
Corrosion activity
Fire damage
Structural integrity and soundness

14. Non Destructive Testing
• Nondestructive testing in the broad sense
refers to methods whereby internal
characteristics of solid structures can be
examined without permanently affecting the
structure. Thus, parts that prove to be
satisfactory under specified test conditions
are not degraded by the test procedures

15. NDT , Introduction
• Nondestructive testing (NDT) is the process of
inspecting, testing, or evaluating materials,
components or assemblies for discontinuities,
or differences in characteristics without
destroying the serviceability of the part or
system. In other words, when the inspection
or test is completed the part can still be used

16. NDT- Purpose
•-Assessment of Existing Structures in the
Absence of Drawings.
•-Quick assessment of the structure

17. NDT -Advantages
• Access to hidden items – “see through
walls”
• Better investigations with NDT
• Rapid accumulation of data
• Generally less expensive than destructive
testing.

18. NDT - Disadvantages
1. More than one test method may be required
2. Environmental conditions may effect or
distort results
3. Construction details & building components
may effect results
4. Some conditions cannot be determined with
a reasonable degree of accuracy without
destructive testing

19. Non destructive Testing
• A : In- situ-concrete test
• - rebound hammer
• - Ultrasonic pulse velocity
• - Windsor probe
• - Pull out test :
• Core cutting / sampling, lab testing of cores
• - Load test

20. Non destructive Testing
• B : Chemical attack
• Carbonation test
• Chloride test
• Sulphate test
• C: Corrosion potential assessment
• Cover meter ( checking cover)
• Half cell potential
• Resistivity meter
• Permeability ( air and water )

21. Non destructive Testing.
• D: Fire damage assessment
• Thermo gravimetric analysis (TGA)
• Differential Thermal analysis (DTA)
• X-ray diffraction (XRD)
• E: Structural Integrity/ soundness
• Ultrasonic pulse velocity ( discontinuities, cracks
and depth of cracks)
• Radiography
• Impact echo test

22. • The rebound hammer can provide a fairly
accurate estimate of concrete compressive
strength.
• The concrete should be 14 to 56 days old.
• Surface Condition:
• The surface of the concrete at the point tested
must be smooth, dry, and free of honeycombing.
Otherwise, rebound readings will be low
Indicating a weaker concrete than is actually the
case. The rubbing stone provided can be used to
grind the surface smooth, if necessary

23. Location of Test PointsLocation of Test Points
• The concrete to be tested must be at least
four inches thick: It is also recommended that
readings be taken only where the concrete
has been in contact with the form. These
conditions are most easily satisfied if the
readings are taken along the edge of the tank
on the sides and ends where the adjoining
concrete face (i.e., wall, top, or bottom) can
support the point of contact.

25. PROCEDURE
• Remove hammer from case and press the
plunger end against a hard surface to release the
plunger from the locked position. (Do not press
lock button while doing this.)
• Position hammer horizontally with plunger end
against wall at a point.
• Slowly apply pressure until hammer fires. This
will occur when only approximately 1/2 inch of
the plunger is still visible. Do not press the lock
button during this step.

26. • A). Remove hammer from case and press the
plunger end against a hard surface to release
the plunger from the locked position. (Do not
press lock button while doing this.)
• B). Position hammer horizontally with plunger
end against wall at a point.
• C). Slowly apply pressure until hammer fires.
This will occur when only approximately 1/2
inch of the plunger is still visible. Do not press
the lock button during this step

27. Procedure Contd.
• With the hammer still pressed against the
wall, read the rebound number off the scale
provided on the hammer. If it is necessary to
move the hammer before reading, press the
lock button. The rebound number should be
read to two significant figures.
• Repeat the above procedure at different
points around the wall until a total of ten
readings has been taken

29. This is based on the principle that the velocity
of an ultrasonic pulse through any material
depends upon the density. Comparatively
higher velocity is obtained when concrete
quality is good in terms of density, uniformity
etc.
Pulse Velocity measurements can be used to
assess the presence of cracks, voids etc.,
quality of concrete relative to standards
requirements.

30. UPV Test contd.
There are three possible ways of measuring
pulse velocity.
 i) Direct transmission
ii) Semi direct transmission
iii) Indirect transmission (surface probing)
Out of the three methods, the direct
transmission method is considered to be the
best

34. condition of concrete based on
pulse velocity are given below
S.No. Pulse Velocity Condition of concrete
I in(Km/Sec.)
•1. Above 4.5 Excellent
•2. 3.5 to 4.5 Good
•3. 3.0 to 3.5 Medium
•4. Below 3.0 Poor

35. PULLOUT TESTPULLOUT TEST
• The fundamental principle behind pull out testing
with LOK-test and CAPO test is that the test
equipment designed to a specific geometry will
produce results (pull-out forces) that closely
correlate to the compressive strength of concrete.
The first method ,using the cast steel disc is called LOK
test. The second method shown in fig.2 using
expandable ring is called CAPO test (i.e. Cut and Pull
out Test). The diameter of both the disc and ring is
25mm. the distance to the concrete surface is also
25mm. the inner diameter of the counter-pressure is
55mm.

38. The relationship between the pullout force Fu
in kN and compressive strength Fc in MPa
The relationship between the pullout force Fu in kN and compressive strength Fc in MPa is given in fig
04/14/17 38

39. Pull out tests are used toPull out tests are used to
 Determine in-situ compressive strength of the
concrete
 Ascertain the strength of concrete for
carrying out post tensioning operations.
 Determine the time of removal of forms and
shores based on actual in-situ strength of the
structure.
 Terminate curing based on in-situ strength
of the structure

40. 4.Core cutter4.Core cutter
The test should be taken at points where
minimum strength and maximum stress are
likely to coincide. But, at the same time, the
core cutting causes some damage to the
member and may impair the future
performance of the member. Therefore, in
slender members, the core should be taken
away from the critical section. For
compression testing, the diameter of the core
should be at least three times the nominal
maximum aggregate size

41. Core Cutter is used to cut the core from the
existing concrete structure for testing the
physical properties of the concrete like
compressive strength, density, water
absorption, crack depth and chemical test like
depth of carbonation and chloride content
etc. It can also be used to inspect the interior
region of the structural members.

42. Core Cutter Set UP

45. • Cover meters are electromagnetic in
operation. Electric currents in a coil winding in
the search head generate a magnetic field
which propagates through the concrete and
will interact with any buried metal present,
such as reinforcing steel.It is the generic term
for equipment used to locate steel reinforcing
bar in concrete and to estimate the thickness
of the concrete cover over the reinforcement

46. 04/14/17 46

47. Tomography means imaging an object by
taking measurements from “slices” of its cross-
section.
Tomography means imaging an object by taking
measurements from “slices” of its cross-section.
04/14/17 47

48. 4/14/17 4

49. 04/14/17 49

50. This test is carried out to assess the quality / uniformity of concrete
at various depths. The instrument consists of a four probe device.
Electrical current is passed through the outer probes & the potential
drop is measured by the inner probes. From the current & voltage
drop measurements, the resistivity of concrete can be measured.
Electrical resistivity = 2(pi)aE/i (in kilo-ohm cm)
where a = distance between probes
= 5 cm in the 1st set of readings
= 10 cm in the 2nd set of readings
E = potential difference between inner two probes in mV
Most useful test in tunnel structure