EMERGING TRENDS IN CIVIL

concretecakeUrban and Civil

Nov 29, 2013 (4 years and 1 month ago)

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EMERGING TRENDS IN CIVIL
ENGINEERING








BY : JATIN ARORA,


ANUJ ARORA,


AKSHAY RUHIL


RAHUL CHHOKAR

NDT’S ON

STRUCTURES

NDT
-
N
ON
D
ESTRUCTIVE
T
EST:


Detect Defects , Dimensions etc. without Damaging
Material.





TESTS ON STRUCTRES

NON
DESTRUCTIVE
TEST

DESTRUCTIVE
TEST

NDT Advantages

Access to hidden items


“see through walls”

Better investigations with NDT

Rapid accumulation of data

Generally less expensive than destructive testing

Evaluation and quality assurance

NDT Disadvantages

More than one test method may be required

Environmental conditions may effect or

distort results

Some conditions cannot be determined with

a reasonable degree of accuracy without destructive
testing

Typical Conditions to Verify

Location and spacing of embedded items


Mild reinforcing steel, post
-
tensioning, conduit


Masonry ties and hardware

Locating hidden flaws and defects (voids, trapped moisture, poor consolidation,
etc.)

Corrosion damage assessment

Concrete properties

Reinforcing steel properties

METHODS FOR NDT ON
STRUCTURES:

IMPACT
-
ECHO METHOD

SCHMIDT/REBOUND
HAMMER TEST

COVER METER

Impact
-
Echo Method


It is a technique used for flaw detection in concrete
surface.



Impact
-
Echo


Based upon evaluation of stress waves generated by an
elastic impact on a concrete surface


Originally developed at Cornell University and NIST
by M.
Sansalone

and N.
Carino


P



Compression

waves

R

-

Rayleigh

waves

S

-

Shear

waves

Impact
-
Echo


Propagating P
-
waves

generated by impact

event. Multiply
-
reflected

waves are detected by

surface sensor.

Reflected waves set

up a
resonance

condition having a

characteristic
frequency

Analogous to a bell’s tone

Impact
-
Echo




Effective in determining
thickness of slabs and depth
of flaws in plate structures


Does not work on beams &
columns


2
0.96 for plate
P
C
D
f




IMPACT ECHO


Applications


Thickness of members


d,b


Location of internal defects


Voids /
delaminations


Repair quality assurance


Internal damage


ASR / DEF / ACR


IMPACT ECHO


Summary



Requires

significant

experience



Powerful

method

for

flaw

detection



Applications

to

quality

control



Verification

of

results

is

critical

REBOUND HAMMER TEST


OBJECTIVE : Determine the Compressive


Strength of concrete.






WORKING OF SRH

Rebound value V/S Compressive Strength

Advantages & Disadvantages



Easy to Handle


Quick


Inexpensive



Used only on Smooth
surfaces


Age of Specimen

COVER METER TESTING


OBJECTIVE : Determine Nominal cover.



PRINCIPLE


Works on Electromagnetic Pulse Induction method

HOW IT WORKS???

ADVANTAGES &


DISADVANTAGES


High Accuracy


Economical


Not Influenced by Moisture



Limited Detection Range


Spacing depends on
Cover depth.

Refrences
:


Wikipedia.com

Civil2010.net

NIST
Jounral



THANK


YOU……..