Non Destructive Testing Laboratory Manual

Non Destructive Testing Laboratory Manual
Department of Civil and Construction Engineering
Non-Destructive Testing
Laboratory Manual
2017 - 2018
Dr. Walid Al-Kutti
Engr. Muhammad Arif Aziz
NDT Lab Manual
S.No
List of Experiments
Page No.
1
SCHMIDT Hammer (Manual)
1–8
2
SCHMIDT Hammer (Digital)
9 – 13
3
Ultrasonic Pulse Velocity
14 – 21
4
Rapid Chloride Permeability Test
22 – 34
5
Moisture Meter
35 – 38
6
Rebar Detector
39 – 42
7
Humidity Measurement
43 – 50
8
COR map II
51 – 57
9
Resipod – Resistivity Test
58 – 62
NDT Lab Manual
Preface to Second Edition
Non-Destructive Test is one of major laboratory tools used to evaluate concrete structure
performance and establish compliance for the quality of concrete.
This Laboratory manual of Non-Destructive Testing for concrete structure will be used in
senior level courses in the BS Program in College of Engineering, and planned to be used in
the Postgraduate Structural Engineering courses.
During the last few years, the College of Engineering in the Imam Abdulrahman Bin Faisal
University developed a state of art, research and professional laboratories in the area of civil
and construction engineering and the main aim of these laboratories is to increase the
engineering skills capabilities in the Kingdom of Saudi Arabia towards improving the
Engineering Practices in Construction industry.
On behalf of College of Engineering, I take this opportunity to thanks Dr.Walid Al Kutti and
Engr. Muhammad Arif Aziz who have taken keen interest in preparation and publication of
this Manual. Without their help it would not have been possible to take this Manual to the
students.
Dr. Othman Subhi Alshamrani
Dean - College of Engineering
Imam Abdulrahman Bin Faisal University
NDT Lab Manual
Chapter 1
Determine Compressive Strength of concrete by using Manual
Rebound Schmidt Hammer
1. Introduction
The rebound hammer test is the most popular method to measure the surface hardness of a
concrete mass. The Swiss engineer Ernst Schmidt first developed a practicable rebound test
hammer.
The basic features of this equipment are shown in Figure – 1 below.
Figure-1: Typical Rebound Hammer
The hammer is very simple, not heavy (about 2 Kg), and has an impact energy of about 2.2 Nm.
It can be operated on vertical, horizontal and inclined surfaces, upwards and downwards, but
it has to be at right angles to the measured surface as indicated in the Figure – 2 below.
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NDT Lab Manual
Figure – 2: Rebound hammer in use
2. Objective
Determine compressive strength of concrete by using Rebound Schmidt Hammer.
3. Applicable standards
ASTM C 805
4. Apparatus
Rebound Schmidt Hammer (Manual)
5. Test procedure
The reading is very sensitive due to local variation in the concrete, especially to aggregate
particles near to the surface. It is better to take numerous readings at each test location, and
then find their mean. Standards vary in their precise requirements, according to ASTM C805
ten reading should be taken.
To take reading the following step should be considered.
Step 1:
Make sure the hammer is calibrated.
Step 2:
The surface must be smooth, clean and dry, and should be preferably formed, but if
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NDT Lab Manual
trowelled surfaces are unavoidable, use a grinding stone to smoothen the test surface as
shown in figure – 3 below.
Figure – 3: Grinding Stone
Step 3:
The plunger is released before use; then it should be pressed strongly and vertically to the
concrete surface and locked in its position.
Step 4:
Take the scale reading on the side window of the hammer, this reading is known as the rebound
number.
Step 5:
Repeat the test at all points and record the rebound numbers, find the mean and check that
each reading didn’t exceed 6 units difference from the mean reading.
Step 6:
Each rebound number will produce a compressive strength from the relationship between the
rebound number and compressive strength on the side of the hammer.
Step 7:
Compressive strength can then be found using a calibration graph of Compressive strength v/s
Rebound (Rebound Hammer conversion chart) as shown in Figure – 4 below.
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NDT Lab Manual
Figure – 4: Rebound Hammer Conversion Chart.
Step 8:
Calculate Mean, standard deviation and coefficient of variation.
6. Observation:
S.No
Rebound
Compressive
Number
Strength (N/mm2)
Mean
Standard
Coefficient of
Deviation
Variance
1.
2.
3.
4.
5.
= _________
6.
7.
8.
9.
10.
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= __________ = __________
NDT Lab Manual
6.1. Mean:
The mean is just the average of a number. It can be easily calculated by adding all the numbers
then divide by how many numbers are there. In other words, it is the sum divided by the count.
It is usually denoted by µ.
𝐌𝐞𝐚𝐧 =
∑ Sum of all numbers
Total Count
Example: What will be the mean of the following numbers?
32, 33,35,29,36
Now we have five reading, thus their mean may have calculated by using the formula
mentioned above,
32 + 33 + 35 + 29 + 36
5
The Mean value (µ) of the reading mentioned above will be 33.
𝐌𝐞𝐚𝐧 =
6.2. Standard Deviation:
The standard deviation is a measure of how spreads out number are. Standard deviation is
denoted by the Greek letter σ. Standard deviation is the square root of variance.
To calculate σ we have to calculate the variance first. The variance can be defined as the
average of squared difference from the mean. To calculate the variance follows these steps.
•
Calculate mean, we have already calculated the mean i.e. 33.
•
Then for each reading, subtract the mean and square the result.
•
Then calculate the average of those squared difference.
Variance =
(32 − 33)² + (33 − 33)² + (35 − 33)² + (29 − 33)² + (36 − 33)²
5
𝐕𝐚𝐫𝐢𝐚𝐧𝐜𝐞 = 6
σ = √𝐕𝐚𝐫𝐢𝐚𝐧𝐜𝐞
So, Standard Deviation σ in our case = 2.449
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NDT Lab Manual
6.3: Coefficient of Variance:
Coefficient of variance can be defined as the ratio of Standard deviation σ to the Mean. The
coefficient of variation (CV) is a normalized measure of dispersion of a probability
distribution.
Coefficient of Variance = Standard Deviation
Mean
𝑪𝒗 =
𝝈
µ
7. Factors influencing the test results:
Results are significantly influenced by all of the following factors
Mix Characteristics:
i.
Cement type
ii.
Cement content
iii.
Coarse aggregate type
Member Characteristic:
i.
Mass
ii.
Compaction
iii.
Surface type
iv.
Age, rate of hardening and curing type
v.
Surface carbonation
vi.
Moisture content
vii.
Stress state and temperature
viii.
Compaction.
7.1: Mix Characteristics:
The three mix characteristics listed above are now examined in more detail.
i.
Cement Type: High alumina cement content may be up to 100% stronger than Portland
cement.
ii.
Cement Content: Do not exceed 10%.
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NDT Lab Manual
iii.
Coarse aggregate: Aggregate type and proportion is highly considerable, since the
strength is governed by both paste and aggregate characteristics. The rebound number
influenced more by the hardened paste. For example, crushed lime stone may yield a
rebound number significantly lower than for a gravel concrete of similar strength which
may typically be equivalent to a strength difference of 6-7N/mm2.
7.2: Member Characteristics:
The members characteristics are listed above are also to be discussed in details.
i.
Mass: The effective mass of the concrete specimen or member under test must be
sufficiently large to prevent vibration or movement caused by the hammer impact. Any
such movement will result in a reduced rebound number.
ii.
Compaction: Since the smooth, well compacted surface is required for the test,
variations strength due to internal compaction differences cannot be detected with any
reliability.
iii.
All
calibration
must
assume
full
compaction.
Surface type: Hardness methods are not suitable for open textured or exposed
aggregate surfaces.
iv.
Age, rate of hardening and curing type: The rate of gain of structure hardness of
concrete is rapid up to the age of 7 days.
v.
Surface Carbonation: Hard carbonate skin may form over the concrete exposed to the
atmosphere. The thickness of carbonate skin may exceed to 20 mm, which may affect
the value of rebound number. Thickness of carbonated skin depends upon the
exposure condition and age.
vi.
Moisture Content: The hardness of wet concrete surface is lower as compare to the dry,
the surface moisture have significant influence over the rebound value or in other
words over the strength of concrete.
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8. Advantages:
•
Less expensive
•
Produce fast results
•
Simple
•
Well established
•
Direct results
•
Unlikely to damage the concrete structure
9. Limitations:
•
Can be affected by many factors (aggregate type, moisture of concrete, surface
quality)
•
Not suitable for early ages concrete
•
Represent surface strength only
•
Not reliable
•
Calibration is needed to get real reading
•
With the same strength of concrete (15-20%) difference may occur.
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NDT Lab Manual
Chapter 2
Determine Compressive Strength of concrete by using DIGISCHMIDT 2000 Concrete test hammer
1. Introduction
DIGI-SCHMIDT rebound hammer is also a useful tool to determine the surface hardness of
concrete. The DIGI-SCHMIDT concrete test hammer consists of the actual concrete test
hammer and the display unit. Each component fit together and is calibrated as one unit as
shown in the Figure – 1 below.
Figure – 1: Display unit with concrete test hammer (Model ND)
The impact bolt of concrete test hammer hit the surface of specimen with a defined force.
After the impact a metal body or hammer rebound. The rebound distance is measured by a
sensor and transmits to the display unit as an electric signal. Then the rebound value R will be
displayed on display unit after converting electric signals by electronics and also displayed the
compressive strength fck of concrete.
There is a certain relationship between the rebound values R and the hardness and strength
of concrete.
The following factors should be considered to determine the rebound value R.
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Impact direction: Horizontal, vertical (upward or downward)
Age of concrete:
Size and shape of sample: Cube, cylinder
2. OBJECTIVE
Determine the compressive strength of concrete by using DIGI-SCHMIDT 2000 - Concrete test
hammer
3. APPLICABLE STANDARDS
ASTM C 805
4. APPARATUS
DIGI-SCHMIDT 2000 - Concrete test hammer
5. TEST PROCEDURE
The reading is very sensitive due to local variation in the concrete, especially to aggregate
particles near to the surface. It is better to take numerous readings at each test location, and
then find their mean. Standards vary in their precise requirements, according to ASTM C805
ten reading should be taken.
To take reading the following step should be taken into account.
Step 1:
Connect the cable to the concrete test hammer and to the display unit on input B as shown in
figure – 1 above.
Step 2:
Attach the transfer cable to the PC for data transmission, and for the transmission to the
printer connect the printer cable with interface RS232.
Step 3:
The surface must be smooth, clean and dry, and should be preferably formed, but if trowelled
surfaces are unavoidable, use a grinding stone to smoothen the test surface as shown in Figure
– 2 below.
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Figure – 2: Grinding Stone
Step 4:
Press the ON/OFF key.
The following data will be displayed on the screen
Device model (Model ND or LD)
Serial number of the concrete test hammer
Installed Software version
Self-test performed: "Test o.k."
Remaining battery life.
Figure – 3: Initial Display on Screen
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Then the measuring display of the previously measured object appears (but without values) as
shown in Figure – 4 below.
Figure – 4: Measuring Display
Step 5:
Before starting the performance, should calibrate the display unit as per the required
standards. Press the MENU key to display the main menu as shown in Figure – 5 below.
Figure – 5: Main MENU
After finishing all the settings on the display unit, press the END key. Now the device is ready
to continue with the "Measuring Process".
Step 6:
Now place the concrete test hammer perpendicular to or against the test surface.
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Step 7:
Drive the concrete test hammer against the test surface with normal speed till the impact is
triggered (high beep acknowledges reading registration).
Repeat this procedure 10 times as per ASTM C805.
Step 8:
After conducting 10 readings press the END button, the display unit will give you the required
results as shown in the Figure – 6 below.
Figure – 6: Required Results
Step 9:
The data will be saved automatically in the display unit. Connect the display unit to the PC with
transfer cable to transfer data.
Step 10:
Transferred data can be treated easily with the software ProVista, version 2.0
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NDT Lab Manual
Chapter 3
Determine the Pulse Velocity, Crack Depth and Compressive Strength
of concrete by using PUNDIT – lab ultrasonic instrument.
1. INTRODUCTION
The ultrasonic Pulse Velocity test (UPV) is one of the popular methods which are used to obtain
information about the interior of a concrete structure with two accessible surfaces
(transducers). The most known instrument, which we used in the lab, is the PUNDIT (Portable
Ultrasonic Non-destructive Digital Indicating Tester) this comes with two transducers and one
calibration rod to adjust the readings before any test.
Figure - 1: PUNDIT LAB
One of the important things in this test is having a good acoustical coupling between the face
of each transducer and the concrete surface by using a medium such as grease, hand cream or
jelly.
1.1: Transducer Arrangement:
There are three major ways through which the transducers may be arranged, as shown in
Figure – 2 below.
a) Opposite faces (direct method)
b) Adjacent faces (semi - direct method)
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NDT Lab Manual
c) Same faces (indirect method)
(a)
(b)
(c)
Figure – 2: Transducer Arrangements: (a) Direct (b) Semi direct (c) Indirect
While the maximum pulse energy is transmitted at right angle to the face of the transmitter,
the direct method is the most reliable method from this perspective of transit time
measurement. In some cases no opposite surfaces can be accessed, therefore this test can also
be also arranged with adjacent surfaces (semi-direct method) Figure – b, and on the same
surface (indirect method) Figure – c.
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2. OBJECTIVE
To determine the pulse velocity, crack depth and compressive strength of concrete by using
PUNDIT - lab ultrasonic instrument.
3. APPLICABLE STANDARDS
ASTM C597
4. APPARATUS:
PUNDIT Lab - Ultrasonic instrument
5. TEST PROCEDURE
5.1: Basic Measurements:
Step 1:
Switch on the mains and apply little amount of grease to the two transducers faces.
Step 2:
Use the reference bar to check and adjust the time reading on the instrument to be the same
as the calibration number on the bar; in our case it is 25.4 μs, as represents in Figure – 3.
Figure – 3: Calibration rod
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NDT Lab Manual
To calibrate the instrument the following steps should be taken into account.
Select System Settings
Set correction factor to 1.0
Select calibration
If necessary, select to enter the transit time as
marked on the calibration rod.
Variable parameter; set as follows:
Up/down keys - fine adjustment
Left/right keys - coarse adjustment.
Center key - enters the value and returns to the
previous menu.
Cancel key - cancels the input and returns to the
previous menu.
Press “Start” to begin the calibration sequence.
The final display shows the expected transit time and
below it the measured transit time. This should
match the value on the calibration rod.
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5.2: Pulse Velocity:
Step 1:
In order to determine the pulse velocity it is compulsory to measure the path length between
the two transducers.
Step 2:
Press the transducers hardly onto the concrete opposite surfaces, and hold for a while to allow
readings to be taken, wait until a consistent reading appears on the display screen of the
instrument.
Step 3:
Record the stable reading, which is the time (T) in microseconds (μs) for the ultrasonic pulse
to travel the path length and pulse velocity (V) in m/s.
Select
“Basic Measurements
Select parameter setting “path length”
Enter the path length
Start the measurement
The display shows:
- Transmission time
- Measured pulse velocity
Save the result or:
Start a new measurement
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5.3: Crack Depth (m):
Select “Compound Measurements”
Select “Crack Depth”
Select parameter setting “b”.
Measure and enter the distance “b”
Transducers in first position – Start
“t1” is measured. Stable reading indicated by a tick
Transducers in 2nd position - Start
“t2” is measured. Stable reading is indicated by a tick
and result screen is displayed.
The display shows:
- “t1”
- “t2”
- Crack Depth
Save the result or press start to repeat the
measurement.
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NDT Lab Manual
5.4: Compressive Strength (N/mm2):
When the pulse velocity is known it is easy to determine the compressive strength of concrete
by using the graph shown in the Figure – 4 below which indicates the relationship between the
pulse velocity and compressive strength of concrete.
50
45
fc = 31.6V - 105
R2 = 0.90
Compressive Strength, MPa
40
35
30
25
20
15
3.70
3.90
4.10
4.30
4.50
4.70
4.90
V, km/s
Figure – 4: Compressive Strength V/S Pulse Velocity
6. OBSERVATION:
S.No
Distance
(mm)
Time (μs)
Pulse Velocity
Crack Width
Compressive Strength
(Km/s)
(mm)
(N/mm2)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
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NDT Lab Manual
7. ADVANTAGES
Low cost
Fast test
Simple
Well established
No damage to the structure
Represent the quality of the concrete (internal compressive strength)
8. LIMITATIONS
Accessible surfaces are needed
Mains needed
Good contacts needed between concrete surfaces and transmitters
Not reliable
Calibration is needed to get real readings
Indirect results (calculations are needed)
Accurate measurements needed
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NDT Lab Manual
Chapter 4
Determine the concrete ability to resist chloride ion penetration.
1. INTRODUCTION
The PROOVE'it© equipment was designed to develop techniques to non-destructively measure
the chloride permeability of in-place concrete in accordance with the standard ASTM C 120208.
The test calculates the amount of electric current passing across the concrete specimen for a
period of standard 6 hours at a standard voltage of 60VDC.
The current (in milliamps) is measured over 6 hours and the ampere – second is achieved by
integration of the curve in order to obtain the Coulombs. This is done automatically. The
Coulombs are as per ASTM C 1202-08, the ability of concrete to resist chloride ion penetration
at 60 VDC over the time of 6 hours of testing, and for the specimen with a diameter of 95 mm
(3 3/4"), 50 mm long, as shown in the table – 1 below.
Table -1: Chloride ion permeability based on charge passed
Coulombs
Chloride Ion Permeability
Typical of
>4000
High
High w/c ratio
4000 - 2000
Moderate
0.4 - 0.5 w/c ratio
2000 - 1000
Low
w/c - ratio <0.4
1000 - 100
Very Low
Latex modif. concrete
<100
Negligible
Polymer concrete
On the other hand, the PROOVE'it© equipment may also use for testing at 10,20,30,40 and 50
VDC and the testing time may change as required.
2. OBJECTIVE
Determine the concrete ability to resist chloride ion penetration.
3. APPLICABLE STANDARDS
ASTM C 1202 - 08
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4. APPARATUS
PROOVE'it© - GERMANN INSTRUMENT A/S
5. TEST PROCEDURE
5.1: Preparing and producing the concrete specimen:
•
The specimen may be cast with in the laboratory in a 100 mm diameter steel molds,
200mm high as shown in Figure – 1 below.
•
On the other hand, the specimen may also produce by coring. The CEL-100 corecase
coring rig is endorsed to be used for cored specimen.
Figure 1: Steel mould for the concrete specimen.
5.2: Conditioning the specimen:
•
Distilled water is required for moistening the samples. The samples in the desiccators
must be fully submerged in the water. To make water free of air, boil it for about half
an hour because de-aerated water can percolate to the concrete specimen simply.
Allow the water to cool off. Now pour the water in a separate bucket or container.
•
Put the specimens in the empty vacuum desiccators, if possible positioned on a floor
near to water drainage outlet. Desiccators should remain at the same position
permanently,
during
final
drainage
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of
water
as
well.
NDT Lab Manual
Figure – 2: The PR – 1081 vacuum pump and the PR – 1070 vacuum desiccator.
•
Maximum 20 nos. of specimens can be placed in desiccators (PR 1070).
•
Clean the lid edge and oil it with silicon oil.
•
Check that all the valves should be closed as shown in Figure – 2 above. Now put the
lid over desiccators.
•
Attach the hose from the vacuum pump to one of the valve nipple over the lid. To
create vacuum, open the valve and switch on the pump.
•
Keep vacuum on for about three hours, then close the valve and switch off the vacuum
pump.
•
Connect another hose to the second valve over the lid of desiccators and put the end
of hose in the beaker with the ready boiled water. Now open the second valve and
permit water to flow into the desiccators. The water should totally cover the
specimens. No air must be permit to enter the desiccators.
•
Open the first valve which is connected to the pump, close the second valve and switch
on the pump for another hour.
•
Switch off the vacuum pump and detach the hoses from both the valves, the valves
should be closed while removing the hoses. Now slowly open the valve to allow air to
enter into the desiccators.
•
Soak the specimen in the container for another 18 hours. Remove lid from the
desiccators and take the specimen out.
•
Let the specimen dry.
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5.3: Select the appropriate rubber gasket for the PROOVE’it© cell:
Table – 2 below indicate the suggested gasket type according to the specimen diameter, and
whether or not it is suggested to epoxy the gasket to the specimen.
Table – 2: Specimen diameter related to the required type of gasket dimension and
recommendation for applying epoxy between the gasket and the specimen
Specimen Diameter
Gasket type
PR – 1010A
Gasket dimensions
(inner diameter, outer
diameter and thickness)
99 mm x 127 mm x 10 mm
Epoxy recommended
between gasket and
specimen
No
104 mm – 102 mm
101 mm – 97 mm
PR – 1010B
93 mm x 126 mm x 10 mm
No
96 mm – 93 mm
PR – 1010C
90 mm x 126 mm x 10 mm
No
78 mm – 75 mm
PR – 1010 – 75
75 mm x 127 mm x 10 mm
Yes
Figure – 3: Rubber Gaskets
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5.4: Installing gasket without epoxy between gasket and specimen:
•
Select the gasket type according to the specimen diameter as shown in Table – 2 above.
In our case PR – 1010B will be use. So there is no need of epoxy between the gasket
and specimen.
•
Clean the gasket, the spacer faces and the stainless steel ring.
•
With silicon oil, slightly oil the end faces of the gasket.
•
Pressed the gaskets on the prepared and moistened specimen at one end. Put the
spacer centrally on the gasket and press another gasket on the specimen’s end.
•
Now put the one cell over the table, make sure that the grooves must be upward. Insert
installed gasket in the groove. Place the other part of cell to complete the arrangement.
•
Ensure that both terminal (red and black) should be in the same direction.
•
Insert four tightening bolts along with washers into the cell holes on each corner.
Tighten opposite bolts with the help of wrenches. The bolts should not be excessively
tightening, which may damage the cell.
•
To check the leakage of cell, put it over the piece of paper and filled the de-aerated
water in the cells with the help of funnel. Scrutinize the water level is remain stable or
not and/or check the leakage spots over the piece of paper.
Figure – 4: Assembled Cell
•
If the cell has leakage it should be disassembled in a sink.Before testing begins, remove
water from the cell which has been filled for leakage check and fill the proper liquids
(3.0% Nacl and 0.3 N NaoH) into reservoir of each cell.
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NDT Lab Manual
•
The proper assembly is shown in figure – 5 below.
Figure – 5: The assembled Prooveit cell
5.5: The assembled PROOVE’it© cell:
After completing the above mentioned steps, the sealed, leak-free and surface dry cell is
ready for testing.
5.6: Connecting the cells to the PROOVE’it© Microprocessor Power supply unit:
Maximum 8 cells can be tested at a time. Cell#1 must be connected to the channel#1 of
power supply unit. Cell#2 with channel#2 and cell#3 with channel#3 etc. it is necessary that
each cell is connected only to each channel power supply binding posts.
Figure – 6: PROOVE’it© Microprocessor Power supply unit
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5.7: Installing the PROOVE’it© software:
Install the software into the computer to begin the test.
5.8: Turning on and running the system:
To begin the software, select the PROOVE’it© icon from start- menu. The following screen will
be shown.
The display screen shows 8 channels. Every channel shows the Status, Voltage – Actual,
Current – Actual, Temperature in ºC, Elapsed time, Predicted Coulombs, Testing time,
Coulombs till now and Permeability Class.
The Predicted Coulombs will appear after 5 minutes of test and will be upgraded after each
next 5 minutes.
As soon as the setup has been set the selected values will be default until changed again.
The following steps should be taken into account to start the test. As soon as the selection is
made, it will be default value till changed by the user.
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Menu
Options
Setup
Voltage of Channels:
Screen
We can choose 10, 20,30,40,50
or 60 VDC. When selected each
channel will use the same
voltage.
Setup
Testing Time:
Testing can be set for all
channels. Individual time can be
chosen for each channel or
default 6 hours for every
channel.
Note: Standard 6 hours is set by
the ASTM C 1202 – 08, if any
other time will be set the
permeability class will not be as
per above standard.
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Menu
Options
Setup
Specimen Diameter:
Screen
To permit the software to
estimate the correct
Permeability Class, it is necessary
to enter the diameter for each
sample. The program will
automatically modify the
corrections for ASTM standard’s
95 mm specimen sixe.
For all channels the default
diameter is 100mm. on the other
hand actual diameter may
entered for each specimen.
Setup
Maximum Temperature:
This option permits entering of
maximum temperature. If the
temperature raised the selected
temperature, the system will
switch off automatically.
The default value is 90 ºC
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Menu
Options
Setup
Start Channel:
Screen
To start the channel use Shift+ F
–keys. Or the channels may also
start by using cursor.
As soon as channel started the
text will be convert into gray,
The channel Status will be turn
ON from OFF
The clock for Elapsed Time will
start, representing by the black
color of clock
The testing will carry on till the selected duration of time has been reached, the test will stop only if the
technician will stop it or the temperature will exceed the max temperature.
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Menu
Options
Unlock
Unlock Channels:
Screen
The black letter will represent
the active channels. To unlock
the channel use the shift+ F –
keys or else use the cursor for
each channel.
Once the channel in unlocked, it
will be appear below the
channel number with red color
“Unlocked”.
After unlocking the channel may be stopped.
STOP
STOP Channel:
To stop the test channel use
stop option in the bar.
Once the channel will be
stopped it will not be started
again before resetting the
channel.
Once a channel is stopped it is posible to save data and reset channel. The data will be saved in the
database under the name of prooveit.mdb in the directory where the software has been installed.
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Menu
Options
Rest
Reset Channel:
Channel
To reset the channel and/or to
Screen
save data select the Reset
Channel from the selection bar
The testing will proceed for the testing time selected, if the channels are not stopped. The
example of screen picture provided below for 60 VDC and 6 hours of testing for 8 channels.
The channel’s Status FIN (Finish) is shown in the first row, also the Permeability Class
indicated on the bottom row for each channels.
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To save the results follow the instructions at the top bar. As soon as results are saved for a
channel the screen will be appear as shown below.
Results
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Chapter 5
Determine the Dampness in Building Material by using James
Instrument Aquameter.
1. Introduction:
The James Instrument Aquameter is an effective and useful instrument which may use to
determine the dampness in building material. This invention facilitate surveyors and other
practitioners to measure the moisture levels of building components such as walls, floors and
other materials easily by using to different modes of operation.
1. Pin Mode
2. Search/Density mode
The Aquameter will display the percentage (%) of moisture in the testing area. Tri color coded
LED display user the condition of tested surface.
Figure – 1: Aqua meter
2. OBJECTIVE:
Determine the Dampness in Building Material by using James Instrument Aquameter.
3. APPARATUS:
Aquameter T – M – 170
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4. TEST PROCEDURE:
Step 1:
To switch on the Aquameter, put in the batteries and press and release the power button.
Step 2:
Press and release the select key to modify the material code setting. The material code appears
on the screen for about 5 seconds. Within this duration the code setting can be modify by using
Up/Hold or Down/Zero keys, when “cdxx” is on display. Where cd stands for code and xx refers
to material number.
Step 3:
(3a) Code Selection for the Pin Mode:
For pin type mode material codes are enlist in the table attached in appendix – 1. If the required
material code is unavailable use standard code “cd00”.
(3b) Code Selection for Search/Density Mode:
For search/density mode the standard material code is “cd10” which is appropriate for
measuring material whose density is like that of fir, oak, pine etc. The user can define the
material codes between “cd01” to “cd20”. The greater the density of the material to be
measured the higher the material code number to be chosen. For concrete wall the user should
select the material could around “cd18”.
Step 4: Moisture Measurements.
Check the current operational mode of the instrument by seeing the symbol “(.)”. The
instrument in the Search/Density Mode if Symbol “(.)” displayed on the screen. If there is no
symbol appears it means that the instrument is in Pin Mode.
(4a) Moisture Measurement Using Pin Mode.
Attach the pin probe with the external jack on the side of the instrument as shown in the
Figure – 2 below. Take out the cap or pin probe by using your thumbs, care should be taken as
the pins are very sharp. Drive the pins tightly into the surface of the material to be tested,
about 6mm.
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Figure – 2: Pin Probe
(4b) Moisture Measurement Using Search Mode.
Grasp the unit tightly in your hand; by using your thumb remove the top of the test unit to
uncover the white sensor bar. This is search probe of instrument. Position the search probe in
opposition to the surface of material (i.e. wall, floor, etc) as shown in Figure – 3 below.
Figure – 3: Search Mode
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Step 5:
Note down the moisture level value from the display unit, and note the moisture condition of
the material from the tri – colour coded LED.
Tri colour coded LED represents the status of moisture. It is controlled by 2 alarm limits i.e. AL1
and AL2. The default settings are AL1 = 13 and AL2 = 18. In case reading is < AL1, the LED will
display Green colour. If the reading is > AL2, the LED will be Red. If the reading within the range
of AL1 and AL2 the LED is Yellow.
Step 6: Zero Adjustment.
The Zero Adjustment feature permits the user to counteract for the effects of changes in
both temperature and humidity. The zero adjustment should be done individually for
different modes.
(6a) Zero Adjustment for Pin mode.
Turn on the meter and make sure that the unit is in pin mode. Allow the pins of the meter to
touch nothing except the surrounding air. Now press the Down/Zero key to make the meter
display read ‘0’. Now the meter is zeroed.
(6b) Zero Adjustment for Search/Density Mode.
Put the search probe of meter about 15cm away from the surface of any material. Now press
the Down/Zero key to make the meter display read ‘0’. Now the meter is zeroed.
Step 7: Changing the Measurement Modes.
To switch between the modes, firmly press and hold the select key till the letter CH will
appears on screen, release the select key, the mode has now changed to another mode.
5. Advantages:
Lightweight, small and easy to handle
Suitable to use and operate
Digital display provide accurate moisture reading
Alarm values are flexible
To save batteries automatic power off.
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Chapter 6
Determine Location of Rebars, measurement of concrete cover and
bar diameter by using Rebar detector.
1. Introduction
The Profometer 5+ rebar locator is a compact, easy handle and lightweight device which is used
to determine the location of rebars, measurement of concrete cover and bar diameter without
damaging the structure. The measuring method is based on the eddy-current principle with
pulse-induction.
Figure – 1: Indicating device with universal probe
The basic unit can perform the following functions:
- Locating rebars
- Measuring concrete covers
- Storing individual cover values and statistical evaluation
- Determining the bar diameters
The Profometer 5+ consists of indicating device and universal probe as shown in the Figure –
1 above. The universal probe is proposed to function in a relation to the direction. So it
responds more sensitively to the rebars parallel to its longitudinal axis, and less sensitive to the
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bars which are perpendicular to its longitudinal axis. That’s why the probe should be placed
parallel to the bars to be tested and moved over them sideward for scanning.
The probe has each small and large measuring range. Use the ← and → keys to change over
between both measuring ranges. The active measuring range is shown in the measuring display
(see Figure – 2) below.
Figure – 2: Measuring Display
If the concrete cover is larger than is shown in the intersection point of the curves in Figure –
3 below the large measuring range had to be used. When the diameter of bar is 16mm, this
applies for a cover of approx.60mm.
Figure – 3: Large and Small Measuring Ranges.
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2. Objective
Determine Location of Rebars, measurement of concrete cover and bar diameter by using
Rebar detector.
3. Applicable standards
BS 1881: Part 204
4. Apparatus
Profometer 5+ - Rebar Detection System
5. Test procedure
Step 1:
•
Connect the universal probe to input A.
•
If you want to use headset, connect it to the socket available on the side showing
headset symbol.
Step 2:
Press the ON/OFF key.
The following data will appear on screen shortly:
Instrument model (model S or SCANLOG)
Instrument serial number
Installed software version
Whether automatic self-test is O.K.
The more or less black battery symbol indicates the battery status
Figure – 4: Initial Display
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Then the measuring display of the previously measured object appears (but without values) as
shown in Figure – 5 below.
Figure – 5: Measuring Display
Step 3:
Before starting the performance, should calibrate the display unit as per the required
standards. Press the MENU key to display the main menu as shown in Figure – 6 below.
Figure – 6: Main MENU
Step 4:
Set all the parameters in the MENU bar. Then take reading by using universal probe.
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Chapter 7
Determine the Humidity of Concrete and other structure by using
Vaisala Structural Humidity Measurement Kit SHM40.
1. Introduction
Vaisala Structural Humidity Measurement Kit SHM40 is a useful tool to determine the humidity
measurement of concrete and any other structure. This equipment has been designed to
determine humidity by using borehole method.
SHM40 kit consists of two main components HM40 indicator and Interchangeable HMP40S
humidity and temperature probe as shown in the Figure – 1 below.
Figure – 1: Vaisala Humidity Measurement Kit SHM40
1. HM40 Indicator.
The main features of HM40 Indicator are,
- HM40 indicator contains connection adapter for HMP40S probe
- Large Graphical Display
- Provide wide range of quantities such as, RH,Td,Tw,a,x,h,T. Quantities describe
in the Table – 1 below.
- 2 nos. AA size batteries are used to power.
- Belt Clip.
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The main functions of HM40 Indicator are,
Where
1 = Quick connection adapter for HMP40S.
2 = Display.
3 = Right function button.
4 = Up arrow button.
5 = Power button
6 = Left function button.
7 = Down arrow button.
8 = Menu Button.
Figure – 2: HM40 Indicator
1.2. Interchangeable HMP40S Humidity and Temperature Probe.
The main features of Interchangeable HMP40S Humidity and Temperature Probe are,
- HMP110 probe and cable with integrated rubber plug.
- May calibrate by Vaisala Service centre.
The main functions of Interchangeable HMP40S Humidity and Temperature Probe are,
Where
1 = HMP110 probe
2 = 30 cm cable
3 = Integrated Rubber Plug.
4 = Quick connection adapter for HM40
Figure – 3: HMP40S Probe
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1.3. Quantities Description.
The quantities calculated by the HM40 indicator with the HMP40S probe are shown in the
Table – 1 below.
Table – 1: Quantities Output by HM40
Quantity
Symbol
Unit(s)
Description
Relative
RH
%
Relative humidity can be defined as the ration of water
Humidity
vapour in the air to the saturation vapour pressure of air
at current temperature.
Dewpoint
Td
˚C
Temperatures at which the water vapour presents in the
˚F
air condense into water at current pressure.
When Td (dewpoint) is below 0 ˚C, the HM40 indicator
display Tf (frost point) rather dewpoint.
Wet
bulb Tw
temperature
Absolute
A
humidity
Mixing ratio
˚C
The minimum temperature which may reach by
˚F
evaporative cooling in the current condition.
g/mᶟ
Quantity of water in Cubic meter (or cubic foot) of air.
gr/ftᶟ
X
g/kg
Ratio of water Vapour mass per kg (or lb) of dry air
gr/lb
Enthalpy
Temperature
H
T
kJ/kg
Summation of the internal energy of a thermodynamics
btu/lb
system.
˚C
Temperature in Celsius or Fahrenheit scale
˚F
2. Humidity Measurement In concrete
Under this heading we will describe the borehole method of concrete humidity measurement.
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2.1. Humidity Measurement in a Borehole.
SHM40 kit is meant for measuring humidity in concrete by using Borehole Method. In this
method, the hole is drilled to the concrete structure over the suitable depth to measure the
humidity. Once drilling has been finished, the hole should be cleaned and covered, and allowed
the air humidity in the air to balance with the humidity in the concrete structure. It will take
around three days to maintain the equilibrium between the airspace humidity and concrete
humidity. After this period of time humidity measurement can be made.
While preparing the hole to measure the humidity by using SHM40 kit, the following points
should be keep in mind,
- The hole should be ϕ 16mm and should achieve the proper depth (see successive
heading Measurement depth for further detail).
- After drilling the hole must be free from the remains material.
- Leave the hole to be cool down after drilling, and allow the humidity of concrete to
equalize with the air.
- Hole should be sealed within equalization time. Use plastic tube and rubber plug to
seal the hole provided in the SHM40 kit.
2.2. Measurement Depth.
The depth of borehole is depending upon the drying condition of the concrete structure.
- When the drying take place only from one side, the measurement depth should be
40% of the overall depth of slab as shown in the Figure – 4a below.
Figure – 4(a): Drying in one direction (Ref)
- If the slab of concrete exposed to air from both the sides, the measurement depth
should be 20% of the overall depth of slab as shown in the Figure – 4b below.
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Figure – 4(a): Drying in Two Direction (Ref)
3. Objective
Determine the Humidity of Concrete and other structure by using Vaisala Structural Humidity
Measurement Kit SHM40.
4. Apparatus
Vaisala Humidity Measurement Kit SHM40
5. Test Procedure
Step 1: Performing a Humidity Measurement in Concrete.
To determine the humidity of concrete by using borehole method, prepare the borehole and
wait for humidity to stabilize.
Step 2: Preparation for Solid Concrete.
To determine the humidity in solid concrete, prepare the borehole 3 days before
measurement, so the equilibrium will be maintained between the humidity of concrete and
the plastic tube.
2.1. Prepare the borehole with the diameter of ϕ16 mm and appropriate depth as
discuss earlier.
2.2. Clean the hole properly using air compressor or vacuum cleaner.
2.3. Push plastic tube (19266HM) into the whole. To press it firmly uses protective cover
as shown in the Figure – 5 below.
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Figure – 5: Inserting the tube into the hole
2.4. Now you have clean borehole with appropriate measuring depth and with the tube
inside. For better results, you can seal the crack around the tube by any suitable
material.
Step 3: Insert probe and seal the hole.
3.1. Now force the protective cover over the plastic tube and twist it so that it slides
down easily, as shown in the Figure – 6 below.
Figure – 6: Locking the cover in place
3.2. Place the probe into the tube and its cable till the probe touches the bottom.
3.3. Seal the plastic tube with rubber cork on the cable. See Figure – 7 below.
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Figure – 7: Sealing the Tube with a Rubber Plug
3.4. Bend the cable inside the protective cover and close the lid. Before starting the
measurement leave probe to be stabilize.
Figure – 8: Cable Folded in the Protective Cover
3.5. Just in case you are not leaving the probe inside the tube, then close the tube using
rubber cork. While starting the measurement you have to insert the probe now, after
having probe wait for 30 minutes for stabilization. As per recommendation it is better
to leave the probe inside the tube to get the reliable results. Recommended setup
during stabilization is shown in the Figure – 9 below.
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Figure – 9: Recommended Setting during Stabilization
Where,
1= Lid
2= Protective Cover
3= Probe Cable
4= Probe
6= Plastic tube
Step 4: Performing the measurement.
4.1. As discuss earlier the equilibrium between the humidity of concrete and hole will
be reach in three days. Before this you will not get the appropriate results.
4.2. Now connect the probe to the HM$) indicator.
4.3. Switch on the HM40 indicator
4.4. Switch to the RH (Relative Humidity) quantity.
4.5. Switch to graph view and make sure the reading is stable
4.6. Note down the required value of relative humidity RH.
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Chapter 8
Determine the Rate of Corrosion in concrete structure by using COR
MAP II.
1. INTRODUCTION
The chemical or electrochemical reaction between a material, usually a metal, and its
environment that produces a deterioration of the material and its properties.
Corrosion of steel reinforcement in concrete is the problem of prime concern facing civil
engineers nowadays because of its increasing occurrence in various structures and high cost
involves in repairing of these structures. An explanation of the corrosion of steel in concrete
starts with the understanding of why steel does not corrode in concrete. The combination of
steel and concrete is feasible construction material of proven durability. A thin layer of oxide
will be formed in the ordinary alkaline environment. Due to this oxide layer steel does not has
expose to the environment and remain prevent as long as remain intact.
The encasement of steel in concrete provides the steel with a more protective environment
and allows it to function effectively as reinforcement. Theoretically, this combination is highly
durable, as the concrete over the steel provides a chemical and physical barrier to the steel,
and can potentially eliminate steel corrosion problems. However, sometimes, it does not
perform accordingly as a result of false design, bad construction techniques or inadequate
construction material used. Beside other factors, corrosion of steel in concrete structures is
the major factor which leads to the deterioration of the concrete structures.
The deterioration of concrete is due to the fact that when steel corrodes, the resulting rust
occupies greater volume than the original steel and exerts greater tensile stresses on the
surrounding concrete, which results in cracking, delamination and spalling of the concrete.
The better understanding of corrosion in concrete is therefore necessary for civil engineers in
order to understand the problem and provide technical solutions of the problem and increases
the life of existing and newly built concrete structures.
To determining the corrosion of steel in concrete is possible through the use of half – cell
measurement, using James COR MAP II.
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Figure – 1: COR MAP II
2. OBJECTIVE
To determine the rate of corrosion in concrete structures by using COR MAP II.
3. APPLICABLE STANDARDS
ASTM Standard C876
4. APPARATUS:
COR – MAP II
5. TEST PROCEDURE
Step 1: Preparation of a New Reference Electrode
Loosen the top of the new electrode and fill about 1/3 with Cu/CuSO4 crystals. Now pour
distilled water and antifreeze solution and screw the top tightly. Now shake the electrodes for
few minutes and ensure that there are some undissolved copper sulphate crystals in the tube.
If it is not, open the electrode again and add some more crystals.
It is suggested to not remove the plastic protective cap from the porous plug assembly on the
bottom of the electrode until it is ready to use. Prepare the Cu/CuSO4 solution a day before of
testing schedule. This will permit ceramic porous plug to become completely saturated with
copper sulphate solutiuon.
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Figure – 2: Cu/CuSO4 Probe
Step 2: Wet bottom Sponge.
Unscrew the bottom reservoir from COR MAP II test probe. Pour approximately ¾ electric
contact solution in the container.
Figure – 3: Bottom Sponge
Step 3:
Now turn on the logger unit by using the power key on the unit. To turn it off press the same
button again.
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Figure – 4: Logger Unit
Step 4: Install a New Map.
The James instrument COR MAP II will allow user to review or install a new map. Turn on the
unit; the menu screen will appear different options, by using up down arrow keys highlight the
option “INSTALL A NEW MAP” as shown in the figure below.
Figure – 5: Install a new map
Press enter; the new map menu sub screen will appear. Choose the desired values by using up
or down arrow keys. Each column has a minimum and maximum value to choose.
•
New Columns = min 20, max 4740
•
New Rows = min 10, max 1180
•
New Frames = up to 250
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Figure – 6: New Frame
Up to 250 frames can be stored in COR MAP II data logger unit. One frame contains 20 columns
and 10 rows; if 20 x 10 is enough for the test being conducted, map no.1 will use only one
frame, 249 maps remain available for the future maps.
Now press enter, a graph screen will appear you are now ready to take reading.
Figure – 7: Graph
Step 5:
Connect the Cu/CuSO4 probe to the 6-pin connector located on the data logger. Using the
provide reel and alligator clip make connection between the exposed rebar, reel and ground
plug on the COR MAP II as shown in the figure below.
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Figure – 8: Measuring Current
Step 6:
Use Cu/CuSO4 probe to take reading as shown in the figure above . The data logger unit will
display the voltage and convert them into 7 letter categories as shown in the table below. Using
the arrow keys on the data logger, move the display cursor to the next grid point. Press the
enter key to store the value into the COR MAP II data logging unit.
The COR MAP II has been designed the readings from the internal high impedance voltmeter
into 7 categories. These 7 categories are permitted for detailed analysis of voltages. The
categories are divided into different categories from A to G. Category A is being the highest
risk of corrosion. The categories and their voltages are mentioned below in Table – 1.
Table – 1: Voltage and risk of corrosion as per category
Category
Voltage
A
-0.420
B
-0.350
C
-0.280
D
-0.210
E
-0.140
F
-0.070
G
-0.000
Risk of Corrosion
90% Chance corrosion is occurring in this area
Corrosion activity over this area is uncertain
90% chance that no corrosion activity is present over this area
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6. ADVANTAGES
Simple
Easy to use
Non-destructive test
High corrosion risk areas can be determined in the concrete.
7. LIMITATIONS
It cannot be used in rock formations.
Not suitable for temperature below 0 C.
An experience operator is required for the correct interpretation of the results.
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Chapter 9
Determine Resistivity of Concrete by using Resipod.
1. Introduction
Assessment of a structure is very important in order to determine its reliability and safety. In
a way, monitoring a structure is same as monitoring human health. Concrete structures are
generally exposed to numerous environmental and dynamic loads, which tend to decrease the
effective performance and durability of the structure. These may result in overall strength
reduction and eventual failure of the structure. Periodic inspections are therefore necessary
to assess the implications, current scenario and the deterioration progress of the structure.
Inspections not only help in preventing the structure failure but also lead to better
management and understanding of the structure.
Currently the structures are generally assessed by visual inspections along with several
destructive and non-destructive tests. Non-destructive assessments/tests have gained
interests among researchers in assessing the structural capability of the structures. Despite
their various advantages, non-destructive testing is not always reliable especially under the
supervision of inexperienced inspectors.
It is often advisable to carry out feasibility study of the structure in order to understand the
nature of Non-destructive tests that should be carried out to assess the problem. Also, the
most important aspect of these tests involves accurate and correct interpretation of the
results, requiring experienced personals and good modern instruments, which make the task
a bit easier.
The resistivity of concrete varies over a complete structure due to a variety of changing site
conditions from day to day so that other methods, like half-cell potential or impact testing,
should be combined to ensure the data. Generally, the probability of the steel corrosion
increases, the concrete resistivity deceases.
Electrical resistivity is one of the practical problems of concrete resistivity testing is to ensure
the good electrical contact between the electrodes and concrete surface. In this method 4
electrodes are located in a straight line on, or just below, the concrete surface at same spacing
as shown in the figure below. A low frequency alternating current is flow between the two
outer electrodes and the voltage drop between the inner electrodes has recorded.
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2. Objective
Determine the Resistivity of concrete structure by using Non destructive test equipment
resipod.
3. Applicable Standard
AASHTO TP 95 – 11
4. Apparatus
Resipod – Concrete resistivity test
5. Test procedure
Step 1:
Press and hold the top button for about 3 sec to turn on the resipod. Once the resipod is on
the following display will be appear (see also Figure – 1 below).
1. Measured Resistivity
2. Battery status
3. Range indication
4. Current indication 20%,40%,60%,80%,100%
5. Indication of scaled reading.
Figure – 1: Resipod’s Display
Step 2: Preparing the concrete surface.
The concrete surface should be clean, and it shouldn’t be coated with any electrically insulating
material. By using rebar locator determines the rebar grid under the concrete surface and
marked grid over the surface. In case the concrete is completely dry it will difficult to take
measurement as the current is carried by ions in pore liquid. Thus, it is compulsory to make
surface wet.
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Figure – 2: Concrete Surface
Step 3:
An appropriate connection should be maintained between the instrument and concrete
surface to get reliable and accurate results. Therefore, before taking reading dip the resipod in
water several times to get accurate reading as shown in the Figure – 3 below
Figure – 3: Water filling in Resipod’s Reservoir
Step 4:
Once the resipod’s reservoirs are filled water it is ready to use. Now place the resipod on the
already prepared wet concrete surface and push it over the surface. The resipod start
measuring the flow of current and the screen will start blinking.
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Figure – 4: Measuring flow of Current
Step 5:
Once the stable reading has been achieved, Press the HOLD button (present over the top) for
3 sec to freeze actual measurements on screen, then press the SAVE (present in the bottom)
to save the reading as shown in the Figure – 5 below.
Figure – 5: Press Hold Button
In this case the fourth reading is saved in memory object 5 as shown in Figure – 6
Figure – 6: Measurement Record
To change the memory location, object number or reading number, just turn off the
instrument and turn on. Now the reading will be safe under the different object no.
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6. Observation
S.No
Sides
Reading ((kΩ.cm)
1
2
3
4
Estimation of the Likelihood of corrosion
Resistivity measurements can be used to estimate the likelihood of corrosion. When the
electric resistivity of the concrete is low, the likelihood of corrosion increase.
When ≥ 100KΩ.cm
Negligible Risk of Corrosion
When = 50 to 100KΩ.cm
Low risk of corrosion
When = 10 to 50KΩ.cm
Moderate risk of corrosion
When ≤ 10KΩ.cm
High risk of corrosion
6. Advantages
1. Determine the risk of early corrosion damage.
2. Simple and accurate testing by sponge insert type sensor
3. No breaking out or drilling of concrete required, as it is a surface test
7. Limitations
1. Only tells the ability of concrete to corrode.
2. Readings can only be taken alongside other measurements.
3. Requiring experienced personals to handle instrument accurately
8.Result
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