ULTRASONIC PULSE VELOCITY TEST/ PUNDIT TEST

INTRODUCTION

Ultrasonic Pulse Velocity is a Non-Destructive test of concrete PUNDIT

(Portable Ultrasonic Non – Destructive Digital Indicating Tester) is the instrument

that used in ultrasonic pulse velocity test. The method is based on the propagation of a

high frequency sound wave which passes through the material. The speed of the wave

varies in function of the density of the material, allowing the estimation of the porosity

and the detection of discontinuities. The idea is to project the sound inside a material and

measure the time necessary for the wave to propagate through it. Once the distance is

known, it is possible to determine the average pulse velocity, which will depend on

several factors such as the nature of the material and the presence of water in the pores,

among others.The test is performed by positioning the source and receiver on either side

of the area in question, then the source sends a compressional wave through the region,

and the receiver records the full waveform on the other side. After receiving the pulse,

the instrument can amplify the pulse and also can measure the time taken by the pulse to

travel through the concrete. This test often used to monitor the uniformity of concrete,

degree of compaction, the estimation of in-site strength, the quality and homogeneity of

concrete in relation to specified standard requirement. UPV methods can play an

important role in this area, since they allow us to monitor the density and homogeneity of

the material, providing information about the strength evolution and about the existence

of internal flaws and defects. The UPV methods have been used in inspection operations

and monitoring of concrete structures. This test allows to measure and to control a series

of basic parameters to determine the concrete quality. However, interpreting the result of

this type of test need to be made in a criteriously form and demand a specific knowledge

of the influential factors. In order to collaborate with the development of the models that

consider these factors, it was decided to carry a study aiming to analyze how the cure

process influences the ultrasonic readings. Using the UPV, it was possible to collect

results of concrete specimens, leading to an opportunity to analyze how the cure process

1 | P a g e

of concrete affects the readings. This analysis is important for concrete durability

prognostics and can be useful considering the economic aspect.

PRINCIPLES

The principle that velocity of sound within a solid mass in the test . V is :

Where is a function,

E is the ratio of Modulus of Elasticity,

Ρ is the Density,

is the acceleration due to gravity.

For assessing the quality of materials from ultrasonic pulse velocity measurement, it is

necessary for this measurement to be of a high order of accuracy. This is done using an

apparatus that generates suitable pulses and accurately measures the time of their

transmission (i.e. transit time) through the material tested. The distance which the pulses

travel in the material (i.e. the path length) must also be measured to enable the velocity to

be determined

from:-

Pulse velocity = Path length / Transit time ; expressed in km/s

Path lengths and transit times should each be measured to an accuracy of about ±1%. The

instrument indicates the time taken for the earliest part of the pulse to reach the receiving

transducer measured from the time it leaves the transmitting transducer when these

transducers are placed at suitable points on the surface of the material. Figure 1 shows

how the transducers may be arranged on the surface of the specimen tested, the

transmission being either direct, indirect or semi-direct. The direct transmission

2 | P a g e

arrangement is the most satisfactory one since the longitudinal pulses leaving the

transmitter are propagated mainly in the direction normal to the transducer face. The

indirect arrangement is possible because the ultrasonic beam of energy is scattered by

discontinuities within the material tested but the strength of the pulse detected in this case

is only about 1 or 2% of that detected for the same path length when the direct

transmission arrangement is used. Pulses are not transmitted through large air voids in a

material and, if such a void lies directly in the pulse path, the instrument will indicate the

time taken by the pulse that circumvents the void by the quickest route. It is thus possible

to detect large voids when a grid of pulse velocity measurements is made over a region in

which these voids are located.

There are 3 types of ways to arrange the transducer.

1. Direct transmission

2. Semi-direct transmission

3. Indirection transmission

3 | P a g e

OBJECTIVES

1. Determine the uniformity of concrete within structure

2. Detection of the presence of cracks, and

3. Estimates in-situ strength of existing concrete using the supplied Correlation

Chart

APPARATUS

1. Reference bar

2. Main control unit (42.5µs)

3. Transducer

4. Receiver

4 | P a g e

PROCEDURE

1. The equipment is calibrated by placing the transducer and receiver at either end of

the reference bar.

2. Four suitable test locations is chosen for each transducer arrangement. The

surface of test location must be clean, smooth and dry. Preferably mould or

formed surface, but it trowelled surface are unavoidable, rub smooth the surface

using a suitable polish material.

3. The path length is measured using measuring tape or calipers.

4. Grease is applied to the surface of test location to ensure proper contact of the

transducers with the concrete surface.

5. The transducers is positioned at the chosen test location. They are ensured

properly in contact with the concrete surface.

6. Three (3) readings are taken per test location. Four (4) readings will be adequate

to plot the best fit straight line for in-direct transmission.

7. The average reading for each test location is calculated. Plot the best fit straight

line for the in-direct transmission. The average velocity is given by slope of the

best fit line.

8. The compressive strength of the test specimen is estimated by using the chart

provided.

5 | P a g e

RESULT

PUNDIT TEST / ULTRASONIC PULSE VELOCITY

Testing result

Part Reading Path Length, s

(km)

Transit Time, t

(s)

Pulse Velocity, v

(V)

Average

1 1st 2.04x10-4 6.61 x10-5 3.0863.0082nd 2.04x10-4 6.82 x10-5 2.991

3rd 2.04x10-4 6.92 x10-5 2.9482 1st 2.04x10-4 7.28 x10-5 2.802

2.7512nd 2.04x10-4 7.72 x10-5 2.647

3rd 2.04x10-4 7.26 x10-5 2.810

3 1st 2.04x10-4 7.24 x10-5 2.8182.8232nd 2.04x10-4 7.34 x10-5 2.779

3rd 2.04x10-4 7.10 x10-5 2.873

Average =

= 2.861 (Poor quality concrete)

6 | P a g e

Calculation :

V = ; expressed in km/s

PART 1 :

1ST reading : V =

= 3.086 km/s

2nd reading : V =

= 2.991 km/s

3rd reading : V =

= 2.948 km/s

Average =

= 3.008 km/s

PART 2 :

1st reading : V =

= 2.802 km/s

2nd reading : V =

= 2.647 km/s

3rd reading : V =

= 2.810 km/s

7 | P a g e

Average : V =

= 2.751 km/s

PART 3 :

1st reading : V =

= 2.818km/s

2nd reading : V =

= 2.779 km/s

3rd reading : V =

= 2.873 km/s

Average : V =

= 2.823 km/s

8 | P a g e

DISCUSSION

i) From the test result, give your comments on the quality of the test specimen.

From our result, the average reading for the part 1 is 3.008 km/s, part 2 is 2.751 km/s and

part 3 is 2.823 km/s. The average strength for this concrete is 2.861 km/s. This mean that

our test result indicate the quality of the concrete is poor.

The quality result that we obtained by us may be differ from the actual quality as this is

the first time we used the instrument. During measurement , there are also possible

mishandling of instrument such as the transmitter and receiver are not tightly with contact

with the surface of concrete , thand grease is not apply properly on the surface of

transmitter and receiver or change of surface moisture . Besides that, it is also possible

that there’s reinforcement steel, void and crack between the transmitter and receiver , or

instrument failure when taking measurement.

To carried out this test and obtain accurate measurements, the following precautions

should followed:

1. The technique normally assumes that the only volatile component is water and

any significant contamination by other volatile compounds would invalidate the

test.

2. The moisture content of all specimens must be identical and kept constant during

testing.

3. Avoid obstacle in between the transmitter and obstacle except the specimen.

4. Before the experiment is started, make sure the apparatus set base in the standard.

5. There’s no impurities on the surface of the specimen.

6. Calibrate the instrument and make sure the condition of instrument is good.

9 | P a g e

(i) What are advantages and disadvantages of the UPV Test?

ADVANTAGES DISADVANTAGES

I) Non-destructive strength testing

determination and monitoring of concrete

strength

i) Requires skills to provide accurate

reading and measurements.

II) Check the uniformity of contrete and

deterioration.

ii) Attenuation of signal in order or soft

masonry restricts distance between

transducers for indirect and semi-direct use.

III) Can detect flaws,cracks,or voids. iii) Coupling material needed between

masonry and transducers, which may alter

the appearance of the masonry.

IV) Measurement of layer thickness and

eleastic modulus.

iv) Grinding may be required to prepare a

rough surface.

V) Equipment readily available and only

moderately expensive.

v) No direct correlation with material

properties.

Pulse velocity tests can be carried out on both laboratory-sized specimens and completed

concrete structures, but some factors affect measurement

1. Path-lengths desired to be at least 12 in. (30 cm) in order to avoid any errors

introduced by heterogeneity.

2. There must be smooth contact with the surface under test; a coupling medium

such as a thin film of oil is mandatory.

3. The presence of reinforcing steel in concrete has an appreciable effect on pulse

velocity. It is therefore desirable and often mandatory to choose lse paths that

avoid the influence of reinforcing steel or to make corrections if steel is in the

pulse path

10 | P a g e

(ii) Can we use UPV to monitor the quality of concrete during construction

We can use UPV to monitor the quality of the concrete during construction.

Ultrasonic pulse velocity is an ideal tool and suitable for establishing whether concrete

is uniform. It can be used on both existing structures and those under construction. Usually,

if large differences in pulse velocity are found within a structure for no apparent reason,

there is strong reason to assume that defective or deteriorated concrete is present. High

pulse velocity readings are generally shows sn indicative of good quality concrete. A general

guidelines between concrete quality and pulse velocity based on UPV is given in Table I.

Longitudinal Pulse (km/s) Concrete Quality

>4.5 Excellent

3.5-4.5 Good

3.0-3.5 Doubtful

2.0-3.0 Poor

(Table 1)

Good correlation can be obtained between cube compressive strength and pulse velocity.

These relations enable the strength of structural concrete to be predicted within ±20 per

cent, provided the types of aggregate and mix proportions are constant. The accuracy of

Ultrasonic Pulse Velocity Test does affected by various factor. Such as age of concrete

beam , surface area condition, skills of person who test it and the inside situation of

concrete. For example ,as concrete ages increases, the rate of increase of pulse velocity

slows down much more rapidly than the rate of development of strength, so that beyond a

strength of 2000 to 3000 psi ( 13.6 to 20.4 MPa ) accuracy in determining strength is less

than ±20 per cent. Accuracy depends on careful calibration and use of the same concrete

mix proportions and aggregates in the test samples used for calibration as in the structure.

In summary, ultrasonic pulse velocity tests have a great potential for concrete control

particularly for establishing uniformity and detecting cracks or defects. Its use for

predicting strength is much more limited, owing to the large number of variables

affecting the relation between strength and pulse velocity.

11 | P a g e

CONCLUSION

Ultrasonic Pulse Velocity(UPV) test is one of the non destructive test. It detect cracks,

strength of concrete and other properties of concretes. It is portable and easy for testing.

Since UPV use velocity principle testing method, hence the frequency of the velocity

should be consider too when taking measurement on different material. Higher frequency

is used when the specimen is high density while for the less dense specimen , the lower

frequency is used.

Besides that, except for mishandling of apparatus that affect the actual reading and

environment condition. Composites of concrete also affect the concrete strength. Such as

the water aggregate ratio, size of aggregate and type of cement.

To minimise the error of measuring, transmitter and receiver must tightly in contact with

surface of concrete when taking the measurent. The surface area of concrete should be

smooth and grease should be apply on the surface of transmitter and receiver.

12 | P a g e

REBOUND HAMMER TEST

Introduction

Rebound hammers are used to determine the compressive strength of concrete.

Compressive strength test results are, among other things, used to determine that the

concrete mixture as delivered meets the requirements of the specification. Structural

failures due to weaker than defined concrete mixes can be catastrophic and may lead to

loss of life. Therefore, quality checks are of paramount importance to serious

construction companies. In addition, non-destructive testing is faster and far more

economical than destructive testing on samples.

Mechanical rebound hammer measure the mechanical travel of the hammer mass on the

rebound. It is affected by its friction on the guide rod, the friction of the drag pointer on

the scale, the influence of gravity during its travel and the relative velocity between unit

and mechanical parts.

Electronic rebound hammers, on the other hand, use the true rebound coefficient that

represents the physical rebound coefficient: Q = 100*((Energy Restored)/(Energy Input))

These rebound hammers measure the velocity of impact and of rebound, immediately

before and after the impact, computing the fraction of energy loss to the specimen under

test. The true rebound coefficient is virtually free of error sources inherent in traditional

concrete test hammers. It is measured optically making the use of a drag and drop pointer

redundant. Thus the true rebound coefficient is less dependent on friction on the guide

rod, the influence of gravity during the travel of the drag pointer and the relative velocity

between unit and specimen. Rebound hammers that measure with the true rebound

coefficient do not need correction for the impact direction. Consequently, impact

direction conversion curves as required with mechanical hammers, are also redundant.

13 | P a g e

Objective

1. To check the uniformity of concrete, and

2. To estimate in-situ strength of existing concrete using the supplied Correlation

Chart.

Apparatus

1. Rebound hammer

2. Reference bar

3. Testing Anvil

14 | P a g e

Procedure

1. The hammer’s reading was calibrated and verified using testing anvil.

2. The abrasive stone (beam specimen) is divided into three span for reading.

3. Appropriate tools are used to clean the surface. Basically, rebound hammer would

prefer mould or formed surface.

4. About 12 readings are taken within the area on each span.

5. The plunger was pressed onto the impact point with horizontally direction to its

surface until the spring loaded mass is release from its locked position.

6. The lock button is used to retain the rebound hammer index readingwhile is still in

the test position.

7. The procedure above are repeated for the next two span.

8. The average readings are estimated.

9. The compressive strength of the beam specimen can be obtained by using the cor-

relation and compressive strength chart.

15 | P a g e

Results

Location : Part 1

Test Date : 20.01.2011 Estimated strength : 30 KN/mᶟ

Concrete Type: RC Beam Hammer Orientation : 90°

Rebound Numbers Reading

Reading 1 36

Reading 2 34

Reading 3 30

Reading 4 34

Reading 5 30

Reading 6 30

Reading 7 42

Reading 8 36

Reading 9 44

Reading 10 32

Reading 11 38

Reading 12 36

Average Rebound Reading 35

16 | P a g e

Location : Part 2

Test Date : 20.01.2011 Estimated strength : 30 KN/mᶟ

Concrete Type: RC Beam Hammer Orientation : 90°

Rebound Numbers Reading

Reading 138

Reading 242

Reading 332

Reading 434

Reading 536

Reading 632

Reading 730

Reading 842

Reading 942

Reading 1046

Reading 1140

Reading 1240

Average Rebound Reading 38

17 | P a g e

Location : Part 3

Test Date : 20.01.2011 Estimated strength : 30 KN/mᶟ

Concrete Type: RC Beam Hammer Orientation : 90°

Rebound Numbers Reading

Reading 1 34

Reading 2 34

Reading 3 34

Reading 4 34

Reading 5 32

Reading 6 36

Reading 7 34

Reading 8 34

Reading 9 44

Reading 10 40

Reading 11 40

Reading 12 40

Average Rebound Reading 36

18 | P a g e

Calculation

Part 1

Average Rebound Reading:

= 36 + 34 + 30 + 34 + 30 + 30 + 42 + 36 + 44 + 32 + 38 + 36

12

= 35

Part 2

Average Rebound Reading:

= 38 + 42 + 32 + 34 + 36 + 32 + 30 + 42 + 42 + 46 + 40 + 40

12

= 38

Part 3

Average Rebound Reading:

= 34 + 34 + 34 + 34 + 32 + 36 + 34 + 34 + 44 + 40 + 40 + 40

12

= 36

19 | P a g e

Average Value

= 3 5 + 38 + 3 6

3

= 36

Compressive Strength (Based On The Correlation Chart)

= 33 N/mm2

20 | P a g e

21 | P a g e

Discussion

(i) Why does non destructive test is carried out?

Nondestructive testing (NDT) is a wide group of analysis techniques used in

science and industry to evaluate the properties of a material, component or

system without causing damage. Because NDT does not permanently alter the

article being inspected, it is a highly-valuable technique that can save both

money and time in product evaluation, troubleshooting, and research.

(ii) State the factors that could be affect the value obtained from the Rebound

Hammer Test? Expain.

a) LIMITED DISTANCE

Can be used to determine the in-place compressive strength of concrete within

a range of 1500 – 8000 psi (10-55MPa)

b) SURFACE SMOOTHNESS

The surface texture significantly affects the R-number obtained. Tests

performed on a rough-textured finish will typically result in crushing of the

surface paste,resulting in a lower number. Alternately, tests performed on the

same concrete that has a hard, smooth texture will typically result in a higher

R-number. Therefore, it is recommended that test areas with a rough surface

be ground to a uniform smoothness. This can be achieved easily with a

Carborundum stone or similar abrasive stone. The FHWA Guide states that

22 | P a g e

research has shown that troweled surfaces and surfaces formed by metal forms

yield rebound numbers 5% - 25% higher than surfaces cast against wooden

forms. It also states that troweled surfaces give a higher scatter of results,

which lower confidence in the estimated strengths. ASTM C 805 states that

where formed surfaces were ground, increases in rebound number of 2.1 for

plywood formed surfaces and 0.4 for high-density plywood formed surfaces

have been noted. The majority of concrete surface hardness is developed in

the first 7 days. However, the concrete will typically continue to gain

significant strength with cement hydration. Testing of concrete less than 3

days old or concrete with expected strengths less than 1000 psi is not

recommended because the R-numbers will be too low for an accurate reading

and will be more destructive to the concrete surface. Concrete continuing to

develop strength with age is again reason for the development of data relating

rebound numbers and the compressive strength of the concrete mixture or

cores from the structure.

c) MOISTURE CONTENT

This has a profound effect on the test results. Dry concrete surfaces result in

higher rebound numbers than wet surfaces. The FHWA Guide references a

study where saturated surface-dry (SSD) specimens were left in a room at

70ºF and air-dried. The specimens gained 3 points in 3 days and 5 points in 7

days. It is recommended that to achieve the most accurate results where the

actual moisture condition is unknown, the surface should be pre-saturated

with water several hours prior to testing and use the correlation developed for

SSD specimens

23 | P a g e

d) SURFACE CARBONATION

With greater amounts of surface carbonation, higher rebound numbers will be

obtained. Rebound numbers on a carbonated surface can be as much as 50

higher than non-carbonated surfaces. Older concrete surfaces may have much

deeper amounts of surface carbonation than younger concrete. ASTM states

that the effects of moisture content and carbonation can be reduced by

thoroughly wetting the surface for 24 hours before testing, and that where a

thick layer of carbonation is present, it may be necessary to use a power

grinder to remove the carbonated concrete and obtain more accurate data.

e) AGGREGATE, AIR VOIDS, AND STEEL REINFORCEMENT

The presence of materials in the immediate area where the plunger comes into

contact with the concrete will have an obviously profound effect as well. If the

test is performed over a hard aggregate particle or a section of steel

reinforcement, the result may be an unusually high rebound number. ASTM C

805 states that tests directly over reinforcing bars with cover less than 0.75

inches should not be conducted. The use of a pachometer or similar device is

recommended for determining the location and cover in structurally reinforced

concrete. Likewise, if the test is performed over a very soft aggregate particle

or an air void, an unusually low rebound number may result. The FHWA

guide reported that for equal compressive strengths, concrete made with

crushed limestone resulted in rebound numbers approximately 7 points higher

than concrete made with gravel, representing a difference of approximately

1000 psi compressive strength estimation. Because of the factors mentioned

above, ASTM C 805 requires that for each test area, ten readings be obtained

with no two tests being closer to one another than one inch. Readings differing

from the average of the ten readings by more than six units should be

discarded. Also, if two readings differ from the average by six units or more,

24 | P a g e

the operator should discard the entire set of readings and take ten new

readings within the test area.

f) TEMPERATURE

Tests should not be performed on frozen concrete surfaces. Wet concrete at

temperatures of 32ºF or less may result in higher rebound numbers. Also, the

temperature of the Swiss Hammer itself in extreme cold (0ºF) may result in

rebound numbers reduced by as much as two or three units.

g) CALIBRATION OF THE SWISS HAMMER

The device itself should be serviced and verified annually or whenever there is

a reason to doubt proper performance. Verification of proper performance of

the device includes the use of a test anvil. The required dimensions and steel

hardness is listed in ASTM C 805. Impacting the proper test anvil with a

properly functioning device will typically result in rebound numbers of 80 ±

2. If the device is believed to not be functioning properly, it is recommended

to send it back to the manufacturer or experienced facility for repairs and re-

verification.

(iii) What does the Rebound Hammer indicate?

25 | P a g e

This test method may be used to assess the in-place uniformity of concrete, to

delineate regions in a structure of poor quality or deteriorated concrete, and to

estimate in-place strength development. To use this method to estimate strength

development requires establishment of a relationship between strength and rebound

number for a given concrete mixture. This simple to use gauge consists of a spring

loaded plunger which, when released, strikes the surface with fixed and constant

impact energy. During the rebound stroke, the mass moves a pointer that indicates the

maximum point of return and at the same time indicates a reference value called

Rebound Number.

The strength of concrete is generally governed by the strength of the cement

paste. Measurement of the strength of the paste can therefore provide a reasonable

indication of the strength of the concrete and the strength can be determined by

inference from the elasticity of the concrete. A practical assessment of elasticity can

be made on site by measuring the rebound of a sprung hammer.

26 | P a g e

Conclusion

From this experiment, we will know Rebound hammer test is a method may be used to

assess the in-place uniformity of concrete. From the results that we obtained, we could

not obtain the uniform data of the quality.

This test also can estimate the in-place strength development by estimating the strength

development which establishes a relationship between strength and rebound number for a

given concrete mixture.

The estimated strength for the RC beam is G30. By referring to the Compressive Strength

Estimation Chart, the compressive strength is 52N/mm². It proves the test specimen is

good in compressive strength

There are many factors other than concrete strength that influences rebound hammer test

results which includes surface smoothness and finish, moisture content, coarse aggregate

type, and the presence of carbonation.

Although rebound hammers can be used to estimate concrete strength, the rebound

numbers must be correlated with the compressive strength of molded specimens or cores

taken from the structure.

27 | P a g e

REBAR LOCATOR TEST (COVERMETER SURVEY)

INTRODUCTION

It maybe necessary to locate the exact position of reinforcement in concrete

members such as beams, columns and slabs during the course of detailed investigation,

especially when core sample is to be extracted from members. Rebar locator or

covermeter can be used to detect the presence of steel in concrete. This test is non-

destructive in nature as it relies on the magnetic field for detecting embedded steel. The

covermeter can also be used to measure the thickness of concrete cover to the reinforcing

bars.

To allow certain constructions and to strengthen the concrete rebars are cast into it.

Drilling through those reinforcing bars is a costly business that can be dangerous: Hitting

a rebar while boring into the reinforced concrete can destroy the drilling instrument and

can severely weaken the concrete structure. An instrument for rebar detection that

quickly and accurately determines the location of the reinforcing bars in the concrete will

significantly decrease construction time and costs.

Principles

An electromagnetic field is generated by a search head. When reinforcing bar or other

metal object lies within the field, the lines of force become distorted. The disturbance

caused by the presence of the metal object in turn produces a local change in the field

strength as detected by the search head and indicated by the meter.

28 | P a g e

OBJECTIVES

I. Determine the location of reinforcement bars in reinforced concrete members.

II. Determine the thickness of concrete cover .

APPARATUS

I. Covermeter

II. Calibration block

29 | P a g e

PROCEDURE

I. Locating reinforcement bars.

a. The measuring head was connected to covermeter.

b. On ‘‘DIAM’’knob, required bar diameter was selected.

c. ‘‘ZERO’’ knob is switched to ON position.

d. “MODE’’ knob is switched to LOCATE position .

e. The sensing head is held away from any metallic object and turn “ZERO”

knob until the red line on the analogue meter is in the center of the two red

arrows and the sound output is at low frequency (at this point the LCD

should be at 0.000v)

f. The sensing head is placed in direct contact with concrete surface and

move over surface until peak signal is obtained.

g. Position on concrete surface is marked.

II. Depth of concrete cover measurement.

a. The measuring head is connected to the covermeter.

b. The “DIAM” knob is turned to known bar diameter (or estimated)

c. The “ZERO” knob is switched to ON position.

d. “MODE” is turned to “CAL”

e. The sensing head is held away from any metallic object and turn “ZERO”

knob until the red line on the analogue meter is in the center of the two red ar-

rows and the sound output is at low frequency(at this point the LCD should be

at 0.000v)

f. The “MODE” knob is turned to “DEPTH”.

g. Black face of head is placed against concrete surface centrally over bar posi-

tion and orientate it parallel to the direction of reinforcement bars to obtain

minimum indication.

h. The depth is read off directly in mm.

30 | P a g e

DISCUSSION

i. The first test specimen is done to obtain the depth of the reinforcement bar (Y20)

and to identify the location of the reinforcement bar (Y20) in the concrete. The

second test specimen is done to determine the depth of the concrete cover mea-

surement and the number of (R10) bar in the concrete.

ii. Advantages of Covermeter test

The sensor design allows the end user to quickly and accurately locate and

determine concrete cover in corners or hard to reach areas.

The exact position and orientation of rebar can be measured quickly and

accurately. Rebar-free areas can be identified forcoring, grinding, resurfac-

ing, or insertion of new machinery mountings.

Disadvantages of Covermeter test

It can easily affected by surrounding metallic particularly ferrous materi-

als.

It cannot detect the second layer of rebar without drill.

iii. No, covermeter cannot be used to monitor the quality of concrete during

construction because it can only be used to detect the location of reinforcement

bars in the concrete and the thickness of concrete cover.

31 | P a g e

32 | P a g e

CONCLUSION

Location of reinforcement bars in the concrete is obtained and the thickness of concrete

cover is determined.

33 | P a g e

REFERENCES

Ultrasonic Pulse Velocity test/ Pundit Test

1.)J. Hola and K. Schabowicz, New technique of nondestructive assessment of concrete

strength using artificial intelligence, NDT&E International 38 (2005), pp. 251–259

2.) http://www.engineeringcivil.com/ultrasonic-pulse-velocity-method.html

3.)ultrasonicpulsevelocity

http://www.tpub.com/content/UFC1/ufc_3_310_05a/ufc_3_310_05a0107.htm

4.)ultrasonic pulse velocity test

http://theconstructor.org/concrete/ultrasonic-pulse-velocity-upv-test/2847/

Rebound Hammer Test

1. Bray, D.E. and R.K. Stanley, 1997, Nondestructive Evaluation: A Tool for De-

sign, Manufacturing and Service; CRC Press, 1996.

2. Chuck Hellier, Handbook of Nondestructive Evaluation, McGraw-Hill Profes-

sional; 2001

3. Peter J. Shull, Nondestructive Evaluation: Theory, Techniques, and Applications,

Marcel Dekker Inc., 2002.

4. Concrete Impact Test, Rebound Hammer.mht

Rebar Locator Test

1. http://www.timeinstrument.com/PDF/ConcreteTestingGauge

2. http://www.paintteststore.com/pages/Concrete-inspection-Covermeter,-Rebar-

locator-Pachometer.html

34 | P a g e

APPENDIX

35 | P a g e

36 | P a g e

37 | P a g e