This document presents information about using non-destructive testing methods to evaluate the structural condition of buildings in Aurangabad City, India. It notes that most buildings in the city are over 30 years old and structural audits are needed. Various non-destructive testing devices are described, including the rebound hammer to assess concrete strength, ultrasonic pulse velocity testing for uniformity, half-cell potential testing for corrosion, core cutting, and the profometer. Test results from these methods can help identify cracks, voids, damage, and determine if repair or retrofitting is required to improve building safety and performance.

1. Presented by,
Ms. Varsha G. Jadhav
M.E.- Structural Engineering,
Civil Engineering Department
Jawaharlal Nehru Engineering College
Aurangabad

2.  Nondestructive testing (NDT) is the process of
inspecting, testing, or evaluating components
without or partial damage
 It analyses and suggests appropriate repairs
and retrofitting measures required for the
buildings to perform better in its service life.
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3.  The issue of Structural Audit has been a
growing interest across all sectors.
 Most buildings in Aurangabad City are over 30
years old.
 The National Crime Records Bureau, in a data-
report states that in the last 10 years, up to year
2012, there has been 448 building collapses, in
Maharashtra, killing over 425 people
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4.  Structural Auditing for all types of R.C.C. Structures
(Residential, Commercial and Industrial)
 Conduction of various workshops for training for
students and consultants in the area of structural
auditing.
 Useful for Projects of B. Tech. and M. Tech. students
 Research and development in the domain of
structural engineering
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5.  Test on actual structure at several location
 Assessment of uniformity of concrete
 Location of cracks, voids & honey combs
 Detection of location damaged due to
overloading or other impacts
 Quality in relation to the IS requirement
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6. 1. Rebound Hammer
2. Ultrasonic Pulse Velocity Meter
3. Half Cell Potential Meter
4. Core cutter
5. Profometer
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7.  To asses quality of concrete in relation to the
standard results
 To estimate compressive strength of concrete
with correlation between rebound index and
compressive strength
 To delineate regions of poor quality concrete
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8.  Calibration:
 The calibration factor is
obtained by testing the
hammer against Steel
having Brinell
Hardness of about 5000
N/mm2
 Co-relation:
 Data is analyzed for 3
positions of Rebound
Hammer (i.e. -90⁰, 0⁰
and 90⁰) to derive
equation of co-relation
between the Rebound
number and
Compressive Strength
 Eg
For 0 deg
Y = 0.013x2 + 0.723x – 5.642
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9.  Consider the following example
 The following 6 values are obtained in a Rebound
Hammer Test for 0⁰ position of Hammer
 29, 31,29,28,28,29 (After considering outliers as per IS
8900)
 Average = 29
 Calibration Factor = 1.036
 Average x Calibration Factor = 29 x 1.036 = 30.044
 Substituting in the co-relation equation
 Y= 0.013(30.0442)+ 0.723(30.044) – 5.642
 = 27.82 N/mm2
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10.  To assess homogeneity & uniformity of
concrete
 To assess quality of concrete in relation to IS
requirement
 Detection of the presence and approximate
extent of cracks, voids
 Measurement of changes occurring with time
in the property of concrete
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11.  Working Principle: The
equipment consist of
transmitter and receiver
probe (20 kHz to 150 kHz)
and time measuring device.
 The transmitter and receiver
probes are pressed against
the concrete surface.
 The physical distance (L)
between the probes are
measured in mm
 The Time (T) required to
traverse the ultrasonic pulse
from transmitter to receiver
is recorded in microsecond
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12.  Less Time required to
traverse through
uniform concrete
 More Time required
to traverse through
damaged/uneven
section
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13.  Velocity (V) is determined by dividing the Length (L) by Time (T)
 V = L/T
 Quality Parameter as per IS 13311-Part 1
Velocity (km/s) Grade
V > 4.5 Excellent
3.5 to 4.5 Good
3.0 to 3.5 Medium
Below 3.0 Doubtful
 Uniformity Parameter (empirical)
Range (Diff between Max and Min) Quality
Less than 0.5 km/sec Uniform
Greater than 0.5 km/sec Doubtful
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14.  This is electrochemical process to detect
corrosion in the reinforcement bar.
 This instrument measures the potential and the
electrical resisistance between the reinforcement
and the surface to evaluate the corrosion activity
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16.  Core Cutting: Core should be cut from
hardened concrete having ends reasonably
even and perpendicular. A core which, before
capping has a maximum height of less than
95% of dia or after capping height less than its
diameter shall not be used.
 Capping: The cut core shall be capped with
suitable material (compressive strength greater
than the compressive strength of concrete and
shall not depart by more than 0.05 mm)
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17.  Correction Factor: For specimen of
height/diameter ratio other than 2. Correction
factor shall be applied as per (Fig 1) of IS 516
 Equivalent Cube Strength of the concrete shall
be determined by multiplying the corrected
cylinder by 5/4
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18.  Dia: 68mm
 Height: 136mm
 Height/Dia: 2:1 (Correction factor 1)
 Failure Load: 45.8 kN
 Area of Core: 3631.68 mm2
 Equivalent Cube Strength: = (5/4) x Load/Area
= (5/4) x 45.8x1000
3631.68
= 15.76 N/mm2
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19.  To assess diameter
 Location of reinforcement
 To asses cover
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20. THANK YOU
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