Proceq DIGI-SCHMIDT 2000 ND, DIGI-SCHMIDT 2000 LD Operating Instructions Manual

Bedienungsanleitung

Operating Instructions

Mode d’emploi

Betonprüfhammer DIGI-SCHMIDT 2000

Concrete Test Hammer Modell ND/LD

Scléromètre à béton

Bedienungsanleitung DIGI-SCHMIDT 2000.qxd 12.12.2002 16:23 Seite 2

English

© 2001 PROCEQ SA Contents 1

Contents

1 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

General Information . . . . . . . . . . . . . . . . . . . . . . 2

Liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Safety Regulations . . . . . . . . . . . . . . . . . . . . . . 2

Standards and Regulations Applied . . . . . . . . . . 3

2 Product Description . . . . . . . . . . . . . . . . . . . . 4

3 Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Connecting the Components . . . . . . . . . . . . . . . 5

Putting the Display Unit into Operation . . . . . . . . 5

4 Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Impact Direction . . . . . . . . . . . . . . . . . . . . . . . . . 6

Mean Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Measure Series Number . . . . . . . . . . . . . . . . . . 6

Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Corrections . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Display Range . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Limit Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Date / Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Data Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

5 Measuring Process . . . . . . . . . . . . . . . . . . . . . 10

Measuring Procedure . . . . . . . . . . . . . . . . . . . . 10

Data Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

6 Maintenance and Care . . . . . . . . . . . . . . . . . . . 13

Cleaning After Use . . . . . . . . . . . . . . . . . . . . . . . 13

Performance Check . . . . . . . . . . . . . . . . . . . . . . 13

Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Form of Delivery . . . . . . . . . . . . . . . . . . . . . . . . 17

Accessories / Spare Parts . . . . . . . . . . . . . . . . . 18

Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . 18

8 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Derivation of the PROCEQ Standard

Conversion Curves . . . . . . . . . . . . . . . . . . . . . . 19

Standard Conversion Curves . . . . . . . . . . . . . . . 19

Creating New Conversion Curve . . . . . . . . . . . . 20

Determining Time Coefficient . . . . . . . . . . . . . . . 21

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2 Safety © 2001 PROCEQ SA

1 Safety

1.1 General Information

1.1.1 Basic Information

The concrete test hammer is designed according to
state-of-the-art technology and the recognized safety
regulations.
Please read through these operating instructions careful­ly before initial startup. They contain important informa­tion about safety, use and maintenance of the DIGI­SCHMIDT 2000 concrete test hammer.

1.1.2 Designated Use

The concrete test hammer is a mechanical device used
for performing rapid, non-destructive quality testing on
materials in accordance with the customer's specifications;
in most cases, however, the material involved is concrete.
The device is to be used exclusively on the surfaces to be
tested and on the testing anvil.

1.2 Liability

Our ”General Terms and Conditions of Sale and
Delivery” apply in all cases. Warranty and liability claims
arising from personal injury and damage to property can­not be upheld if they are due to one or more of the follo­wing causes:

- Failure to use the concrete test hammer in accordance
with its designated use

- Incorrect performance check, operation and mainte­nance of the concrete test hammer

- Failure to adhere to the sections of the operating
instructions dealing with the performance check, ope­ration and maintenance of the concrete test hammer

- Unauthorized structural modifications to the concrete
test hammer

- Serious damage resulting from the effects of foreign
bodies, accidents, vandalism and force majeure

1.3 Safety Regulations

1.3.1 General Information

- Perform the prescribed maintenance work on schedule.

- Carry out a performance check once the maintenance
work has been completed.

- Handle and dispose of lubricants and cleaning agents
responsibly.

1.3.2 Unauthorized Operators

The concrete test hammer is not allowed to be operated
by children and anyone under the influence of alcohol,
drugs or pharmaceutical preparations.
Anyone who is not familiar with the operating instructions
must be supervised when using the concrete test hammer.

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© 2001 PROCEQ SA Safety 3

1.3.3 Safety Icons

The following icons are used in conjunction with all
important safety notes in these operating instructions.

Danger!
This note indicates a risk of serious or
fatal injury in the event that certain rules of
behavior are disregarded.

Warning!

This note warns you about the risk of material
damage, financial loss and legal penalties
(e.g. loss of warranty rights, liability cases, etc.)

This denotes important information.

1.4 Standards and Regulations Applied

- DIN 1048, part 2

- ASTM C 805

- B 15-225

- NEN 3880 A 607

- PN-74B 06262

- C 30-67 BDS 3816-72

- HS 201/1-72

- ISO/DIS 8045

- EN 12398

- ENV 206

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4 Product Description © 2001 PROCEQ SA

2 Product Description

Fig. 2.1 Display unit with concrete test hammer

(Model ND/LD)

The DIGI-SCHMIDT 2000 concrete test hammer compri­ses the actual concrete test hammer and the display unit.
Both components belong together and are calibrated as
one unit.
The impact bolt of the concrete test hammer strikes the
surface of the concrete with a defined force. After the
impact, a metal body, the so-called hammer (see pos. 14
in Fig. 6.2, page 16), rebounds. The rebound distance is
measured by a sensor and passed on to the display unit
as an electrical signal. The signal converted by the elec­tronics is shown on the display unit as rebound value R
and, if necessary, displayed together with the correspon­ding compressive strength of the concrete, fck.

There is a specific relationship between the rebound
value R and the hardness and strength of the concrete.
The following factors must be taken into account when
ascertaining rebound values R:

- Impact direction: horizontal, vertically upwards or
downwards

- Age of the concrete

- Size and shape of the comparison sample (cube,
cylinder)

Model ND can be used for testing:

- Concrete items 100 mm or more in thickness

- Concrete with a maximum particle size < 32 mm

Model LD can be used for testing:

- Items with small dimensions (e.g. thin-walled items
with a thickness from 50 to 100 mm)

With Model LD, it may be necessary to clamp
the items to be tested prior to measurement in
order to prevent the material from deflecting.

- Items made from artificial stone which are sensitive to
impacts

For Technical Data, see page 18

Display unit

Concrete test hammer

Test hammer cable

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English

© 2001 PROCEQ SA Startup 5

3 Startup

3.1 Connecting the Components

• Connect the Test hammer cable to the concrete test
hammer and to the display unit at input B.

• Connect the transfer cable for data transmission to the
PC, and for transmission to the printer, connect the
printer cable to interface RS232.

3.2 Putting the Display Unit into

Operation

• Press the ON/OFF key.

The following data are briefly displayed:

- Device model (Model ND or LD)

- Serial number of the concrete test hammer on the

left and that of the display unit on the right side

Check whether the serial number of the con­crete test hammer on the display corresponds
to the number on the device.

- Installed software version

- Self-test performed: ”Test o.k.”

- Remaining battery life

Then the measuring display of the previously measured
object appears (see Fig. 3.1, but without values).

If no display appears, replace the batteries.

Fig. 3.1 Measuring display

The symbols and values only appear if they have been
set or if a measurement series has been performed.

• Adopting the menu settings from the previous measu-

rement:

Continue with ”Measuring Process”, page 10.

• Making new settings:
Continue with ”Settings”, page 6.

Last measured value
Minimum value
maximum value
Standard deviation
Mean value

Compressive strength
of the concrete

Unit
No. of test impacts

47
48

48

49

41 42 43 44 45 46

41 Impact direction 46 Measurement series no.
42 Calculation of mean value 47 Display range
43 Conversion curve 48 Limit value
44 Eliminate outliers 49 Rebound values displayed
45 Shape coefficient αs as bar chart

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6 Settings © 2001 PROCEQ SA

4 Settings

The display unit has a menu with user navigation. Please
follow the instructions in the respective display fields.

• Press the MENU key to display the main menu:

Fig. 4.1 Main menu

Warning!

Check the settings before performing a
measurement! This applies in particular for the
impact direction and for the shape and time
coefficient.

4.1 Impact Direction

• Select the symbol for the desired impact direction.

The rebound value is automatically corrected according
to the preselected impact direction.

4.2 Mean Value

The mean value is calculated from the number of test
impacts n entered or after a measurement series has
been completed by pressing the END key.

• Where possible, enter at least n = 10 or n = 12
(see under “Mx”, example on page 9).

The actual mean value is displayed after every test
impact.

4.3 Measure Series Number

• At the start of a measurement series, you can enter a
number (max. 6 figures).

The number is automatically incremented by 1 after the
first test impact of the new measurement series.

4.3 Conversion

4.4.1 Unit

• Select the unit in which the compressive strength of
the concrete is to be displayed (N/mm

2

, MPa, psi,

kg/cm2).

Select menu option

Call selected option
Call measuring display

with the selected functions

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© 2001 PROCEQ SA Settings 7

4.4.2 Select Curve

The compressive strength of the concrete fck can be cal­culated from the rebound value R by means of conver­sion curves. There are 3 options available for calculating
the compressive strength of the concrete:

- No conversion

- Select 5 internal conversion curves, or

- Choose between 2 programmed PROCEQ standard
curves (fck 7 days and fck 14 to 56 days).

No Conversion

Select ”No Conversion”.
At the end of a measurement series, only the average of
the rebound values  in relation to the impact direction is
displayed.
The corresponding compressive strengths of the con­crete can be taken from the conversion curves in Fig. 8.1
and Fig. 8.2 under ”Standard Conversion Curves”,
page 19 and page 20.

Internal Conversion Curves

Parameters a, b and c of the curve functions must first
be set in the sub-menu ”Set up curve”.

• Under line number 1 to 5, select the conversion curve.

Select PROCEQ Standard Curves

For the derivation of the PROCEQ Standard curves, refer
to ”Derivation of the PROCEQ Standard Conversion
Curves”, page 19.

• Select conversion curve A in line no. 7 for concrete
with an age of 7 days (fck7) or the conversion curve in
line no. 28 for concrete with an age of 14 - 56 days
(fck28).

4.4.3 Set up Curve

The curve no. (1 to 5) and the parameters a, b and c
(see under ”Creating New Conversion Curve”, page 20)
can be set using the arrow keys.

4.5 Corrections

4.5.1 Shape Coefficient αs

The PROCEQ standard curves fck7 and fck28 are valid
for sample cubes with a 200 mm side for EPROM
versions up to 1.3 or from a 150 mm side from EPROM
version 2.0. If test specimens with different dimensions
are used for determining the compressive strength in the
pressure testing machine, the shape coefficient in the
first line is to be set or selected in line 2 to 4.

Shape of the test specimen:

1. Line: ”variable”, see Table 4.1

Tab. 4.1 Shape coefficients

Test specimen Shape coeffi-

cients

EPROM version up to 1.3 from 2.0
Cube 300 mm and cylinder Ø 100x100 mm 0,90 0,85
Drill core Ø 100x100 mm 1,07 1,02
Drill core Ø 50x56 mm 1,09 1,04

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8 Settings © 2001 PROCEQ SA

Shape of the test specimen: Shape coefficient also

applies for:
2nd Line: 200/200/200 Cylinder Ø 200 x 200 mm
3rd Line: 150/150/150 Cylinder Ø 150 x 150 mm
4th Line: Ø 150/300 mm Cylinder Ø 6” x 12”

4.5.2 Time Coefficient αt
There are two options available:

- Determining ones own time coefficient

- Time coefficient as a function of the carbonate pene-

tration depth

Ones Own Time Coefficient

• Select αt, and enter the time coefficient determined.

See example under ”Determining Time Coefficient”,
page 21.

Time Coefficient as a Function of the Carbonate
Penetration Depth

The reduction factors derived from the Chinese standard,
JGJ/T23-92 and based on the carbonate penetration
depth ”d” (in mm) provide a further option (from EPROM
version 2.0).

• Select ”d”, and set a value between 1 and 6 for the

defined carbonate penetration depth (in mm). For car­bonate penetration depths over 6 mm, enter 6. The
corresponding reduction factor is set automatically.

4.5.3 Eliminate Outliers

The following 4 functions can be selected: ”0”, M1, M3
and Mx. Using function ”0”, individual values can be
deleted manually.
Using the functions M1, M3 and Mx, values are elimina­ted automatically.

”0”: Eliminating Individual Values

Individual values can only be deleted with this function.

• Too high or too low measured values can be eliminated
directly during the measurement process with the
PRINT key.

M1: Eliminate Highest and Lowest Value

The highest and lowest measured values are deleted
provided at least 6 measured values are present.

M3: Delete Values with Deviations of over 20 %

Values which deviate 20 % or more from the mean value
after completion of a measurement series are deleted.
The number of test impacts shown on the display is
reduced by the number of deleted test impacts. Four
beeps are output to request replacement of the test
impacts deleted by new ones. The result of the measure­ment appears on the display as soon as ”n” test impacts
have been successfully performed.

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© 2001 PROCEQ SA Settings 9

Mx: Delete the Lowest and Highest Values

Only possible from EPROM version 2.0. The amount ”m”
of both the lowest and highest values are deleted.

• Under ”m”, enter the number of measured values to be
eliminated. See also the number of test impacts ”n”
set, under ”Mean Value”, page 6.

Example: If ”m” = 3, then at least 12 should be set for ”n”.

4.6 Display Range

The display range for the rebound value R on the display
can be adapted to the testing range.

• Enter R

min

and R

max

.

4.7 Limit Values

The limit marks on the display serve to aid fast recogni­tion of deviations from the measured values.
The range within which the rebound values R are to lie
can be selected (see Fig. 3.1 ”Measuring display”,
page 5).

The selected limit values are not saved!

• Enter R

min

and R

max

.

4.8 Language

• The display texts can be selected in the language
required.

4.9 Date / Time

The inbuilt clock saves the measured values together
with the test date and time.
Correct the values set, if necessary.

4.10 Data Output

See under ”Data Output”, page 11.
When all the settings have been made on the display
unit, press the END key. The device is ready to continue
with the ”Measuring Process”, page 10.

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10 Measuring Process © 2001 PROCEQ SA

5 Measuring Process

5.1 Measuring Procedure

Preferably do perform measurements at tem­peratures between 10 °C and 50 °C only.

The items in (brackets) are illustrated in Fig. 5.4, page 11.
Perform test impacts with the concrete test hammer on a
smooth, hard surface, without the cable connected to the
display unit, before taking any measurements which you
are going to evaluate.

Fig. 5.1 Preparing the test surface

Warning!

The impact plunger (1) generates a recoil
when it deploys. Always hold the concrete test
hammer in both hands!

Fig. 5.2 Deploying the impact plunger (1)

Danger!
Always hold the concrete test hammer in
both hands, perpendicular to the test sur­face, before you trigger the impact!

Each test surface should be tested with at
least 10 impacts.
The individual impact points must be spaced at
least 20 mm apart.

Fig. 5.3 Performing the

test

• Enter the basic settings as
described under ”Settings”,
page 6.

• Use a grindstone to smoothen
the test surface.

• Position the concrete test ham­mer perpendicular to the test
surface.

• Deploy the impact plunger (1)
by pushing the concrete test
hammer towards the test sur­face until the pushbutton (6)
springs out.

• Position the concrete test ham­mer perpendicular to and
against the test surface. Push
the concrete test hammer
against the test surface at mo­derate speed until the impact is
triggered (a high beep acknow­ledges registration).

• Repeat this procedure for the
whole measurement series.

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© 2001 PROCEQ SA Measuring Process 11

• Obvious outliers can only be eliminated directly after
the particular test impact with the PRINT/STORE key.

End Measurement Series:

• After the last impact of a measurement series has
been carried out, a low beep sounds. If n = 0 was set
under ”Calculation of Mean Value”, you must end the
measurement series with the END key.

New Measurement Series:

The measured values set remain unaltered:

• Continue from Fig. 5.1 on page 10 with ”Preparing the
test surface with a grindstone”. The measurement
series number is automatically incremented by 1 after
the first test impact of the new measurement series.

Setting new values:

• Press the MENU key.

• Enter the new values as described under ”Settings”,
page 6.

Complete Measurements:

• Push the concrete test hammer against a hard surface
at moderate speed. When the impact is triggered, press
push button (6). Impact plunger (1) is locked in a retrac­ted position and the impact spring is under no load.

Fig. 5.4 Locking the impact plunger (1)

5.2 Data Output

The data are saved automatically in the display unit
(max. 500 measurement series of 10 measurements).
When the memory is full, the oldest data are overwritten.

5.2.1 Transfer Memory

The data can be transferred to an MS Excel format
under Windows.

• Connect the display unit using the transfer cable
(Order No. 330 00 456) to the PC.

More information on the subject can be found
in the leaflet ”Data Transfer to the PC”.

Fig. 5.5 Transferring data to an MS Excel format

1

6

Year

Measurement series number

Month Day Hour Minute

*Impact Conversion αt αs Carbonate penetra-

direction curve tion depth ”d” (in mm)

Eliminate outliers

Measured values R

R R Min. R Max. s fck Unit from fck

* Impact direction: 12345

   

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12 Measuring Process © 2001 PROCEQ SA

5.2.2 Clear Memory

Objects cannot be deleted individually.

You can only delete the entire memory
contents. This action cannot be undone after it
has been confirmed.

5.2.3 Display Memory

The measurement series number, the impact direction of
the concrete test hammer and the measured rebound
values R after deletion of the outliers, as well as the
average of the rebound values  or of the compressive
strength of the concrete are displayed.

5.2.4 Output on the Printer

For data transmission, use the printer cable
Art. No. 330 00 460. Printing can be performed on all
commercially available printers with a serial port. The
following printing options are available:

- Printer is connected to the display unit during measu­rement (online):
After completion of a measurement series (the prese­lected no. of test impacts has been performed), the
data are sent to the printer. Transmission is also pos­sible at any time by pressing the PRINT key.

- Printing via memory:
In the sub-menu ”Display memory” the desired measu­rement series can be selected with the ,  keys.
Printing is performed by pressing the PRINT key.

Fig. 5.6 Example of a print protocol

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© 2001 PROCEQ SA Maintenance and Care 13

6 Maintenance and Care

6.1 Cleaning After Use

Warning!

Never immerse the concrete test hammer in
water or clean it under a running tap! Use
neither abrasives nor solvents for cleaning!

6.1.1 Concrete Test Hammer

• Deploy the impact plunger (1) as described in Fig. 5.2,
page 10.

• Wipe the impact plunger (1) and housing (3) using a
clean, dry cloth.

6.1.2 Display Unit

• Clean the display unit and measuring equipment with a
clean, dry cloth after use.

• Clean the input sockets and connectors with a clean,
dry brush.

6.2 Performance Check

6.2.1 Concrete Test Hammer

If possible, carry out the performance check every time
before you use the device, however at least every 1000
impacts or 3 months.

Fig. 6.1 Performance check of the concrete test hammer

Proceed as described in ”Maintenance”,
page 14 if the values are not within the
tolerance range specified on the testing anvil.

• Put the concrete test hammer
into operation as described
under ”Startup”, page 5.

• Place the testing anvil on a
hard, smooth surface (e.g.
stone floor).

• Clean the contact surfaces of
the anvil and the impact plun­ger.

• Perform about 10 impacts with
the concrete test hammer and
check the result against the
calibration value specified on
the testing anvil.

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14 Maintenance and Care © 2001 PROCEQ SA

6.2.2 Display Unit

• Check the surface of the outer sheath of the cable and
the connector for damage.

• Check the life of the batteries.

• If a battery life of 4 to 6 hours is indicated on the dis­play unit, you should take a new set of batteries to the
measuring site.

6.3 Storage

• Store the concrete tester and accessories in the origi­nal case in a clean, dust-free room.

• If the unit is not used for a long period of time, remove
the batteries.

6.4 Maintenance

We recommend to check the concrete test hammer for
wear after 2 years at most and clean it. Do this as des­cribed below.

The concrete test hammer can either be sent
to a service center authorized by the vendor or
else it can be maintained by the operator
according to the following description.

The items in (brackets) are illustrated in Fig. 6.2, ”Length­ways section through the concrete test hammer”, page 16.

6.4.1 Stripping Down

Warning!

Never strip down, adjust or clean the slider
and guide rod (4) (see Fig. 6.2, page 16),
otherwise the slider friction may change.
Special tools are required to readjust it.

• Position the concrete test hammer perpendicular to the
surface.

Danger!
The impact plunger (1) generates a recoil
when it deploys. Therefore always hold the
concrete test hammer with both hands!
Always direct the impact plunger (1)
against a hard surface!

• Deploy the impact plunger (1) by pushing the concrete
test hammer towards the surface until the push
button (6) springs out.

• Unscrew the cap (9) and remove the two-part ring (10).

• Unscrew the rear cover (11) and remove the compres­sion spring (12).

• Press the pawl (13) and pull the system vertically up
and out of the housing (3).

• Lightly strike the impact plunger (1) with the hammer
mass (14) to release the impact plunger (1) from the ham­mer guide bar (7). The retaining spring (15) comes free.

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© 2001 PROCEQ SA Maintenance and Care 15

• Pull the hammer mass (14) off the hammer guide bar
together with the impact spring (16) and sleeve (17).

• Remove the felt ring (18) from the cap (9).

6.4.2 Cleaning

• Lay all parts except for the housing (3) in kerosene and
clean them using a brush.

• Use a round brush (copper bristles) to clean the hole in
the impact plunger (1) and the hammer mass (14)
thoroughly.

• Let the fluid drip off the parts and then rub them dry
with a clean, dry cloth.

• Use a clean, dry cloth to clean the inside and outside
of the housing (3).

6.4.3 Assembly

• Before assembling the hammer guide bar (7), lubricate
it slightly with a low viscosity oil (one or two drops is
ample; viscosity ISO 22, e.g. Shell Tellus Oil 22).

• Insert a new felt ring (18) into the cap (9).

• Apply a small amount of grease to the screw head of
the screw (20).

• Slide the hammer guide bar (7) through the hammer
mass (14).

• Insert the retaining spring (15) into the hole in the
impact plunger (1).

• Slide the hammer guide bar (7) into the hole in the
impact plunger (1) and push it further in until noticeable
resistance is encountered.

Prior to and during installation of the system
into the housing (3), make sure that the
hammer mass (14) does not get held by the
pawl (13).
Hint: Press the pawl (13) briefly.

• Install the system into the housing (3).

• Insert the compression spring (12) and screw the rear
rear cover (11) into the housing (3).

• Insert the two-part ring (10) into the groove in the
sleeve (17) and screw on the cap (9).

• Carry out a performance check.

Send in the device for repair if the mainte­nance you perform does not result in correct
function and of the calibration values specified
on the testing anvil are not achieved.

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Key:

1 Impact plunger
2 Test surface
3 Housing, complete
4 Slider with guide rod
5 Not used
6 Push button, complete
7 Hammer guide bar
8 Guide disk
9 Cap (for model LD red)

10 Two-part ring

11 Rear cover (for model LD red)
12 Compression spring
13 Pawl
14 Hammer mass: 14.1 model ND, 14.2 model LD
15 Retaining spring
16 Impact spring
17 Guide sleeve
18 Felt washer
19 Resistance element with input socket
20 Trip screw
21 Locknut
22 Pin
23 Pawl spring

16 Maintenance and Care © 2001 PROCEQ SA

6.4.4 Concrete Test Hammer Model ND/LD

Fig. 6.2 Lengthways section through the concrete test hammer

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© 2001 PROCEQ SA Data 17

7 Data

7.1 Form of Delivery

Model ND / LD

Contents of Package Model ND Model LD

Article no. 340 00 202 340 00 211
Concrete test hammer zz
Display unit zz
Carrying strap zz
Test hammer cable zz
Transfer cable zz
Grindstone zz
Protection sleeve for zz

display unit
Operating instructions zz
Calibration certificate zz
Carrying case zz

325 x 295 x 105 mm
Total weight 3 kg 3 kg

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7.2 Accessories / Spare Parts

Designation Article no.

Protection sleeve for display unit 330 00 470
Transfer cable 9/9-position 330 00 456
Printer cable 9/9+25-position for printer 330 00 460

with serial port
Test hammer cable 380 02 510
Grindstone 310 99 037
Carrying case 340 00 281

7.3 Technical Data

7.3.1 Display Unit

- Measuring range from 10 to 70 N/mm

2

compressive

strength of the concrete

- Non-volatile memory for max. 500 measurement
series of 10 measurements each

- Graphics LC display, 128 x 128 pixels

- Interface RS232

- Power supply with 6 batteries, 1.5 V, LR6 design for an
operating time of approx. 60 hours

- Permissible ambient conditions of -10 °C to +60 °C

7.3.2 Concrete Test Hammer

Model ND Model LD

Impact energy: 2.207 Nm 0.735 Nm

18 Data © 2001 PROCEQ SA

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© 2001 PROCEQ SA Appendix 19

8 Appendix

8.1 Derivation of the PROCEQ Standard
Conversion Curves

The conversion curves Fig. 8.1 and Fig. 8.2 for the con­crete test hammer are based on measurements taken on
very many sample cubes.
The rebound values R of the sample cubes were measu­red using the concrete test hammer. The compressive
strength was then determined with the pressure testing
machine. In each test, at least 10 test hammer impacts
were performed on one side of the sample cube which
was lightly clamped in the press.

Material of the sample cubes:
All cubes were made from concrete consisting of good
quality fine gravel (maximum particle size Ø 32 mm) and
Portland cement.

Empirical values:

The conversion curve is practically independent of the:

- Cement content of the concrete

- Particle gradation

- Diameter of the largest particle in the fine gravel mix-

ture, providing the diameter of the maximum particle is
< 32 mm

- Water/cement ratio

8.2 Standard Conversion Curves

Standard Conversion Curve for Concrete Test
Hammer Model ND

Mean value  has already been corrected in relation to
the impact direction

Fig. 8.1 Model ND: Conversion curve based on the average

compressive strength of a cylinder and the rebound
value R

fck

cyl.

m: average compressive strength of a cylinder

(probable value)

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Standard Conversion Curve for Concrete Test
Hammer Model LD

Mean value  has already been corrected in relation to
the impact direction

Fig. 8.2 Model LD: Conversion curve based on the average

compressive strength of a cylinder and the rebound
value R

Limits of Distribution
fck

cyl.

: The max. and min. values are set so that 80 %

of all test results are included.

8.3 Creating New Conversion Curve

Experience has shown that deviations from the normal con­version curves occur under the following circumstances:

- Artificial stone products with an unusual concrete com­position and small dimensions. It is recommended to
perform a separate series of tests for each product in
order to determine the relationship between the rebound
value R and the resistance to pressure.

- Aggregates made from low strength, lightweight or clea­vable stone (e.g. pumice, brick rubble, gneiss) result in
a strength value lower than shown on the conversion
curve.

- Gravel with a preponderance of smooth, polished surfa­ces and spherical shape results in values for compres­sive strength which are lower than those ascertained by
the rebound measurements.

- A strong, dry mixed concrete (i.e. with low sand content)
which has not been worked adequately may contain
gravel agglomerations which are not visible from the
surface. These affect the strength of the concrete
without however influencing the rebound values R.

- The concrete test hammer gives inadequate rebound
values R on recently applied, green concrete or con­crete which has hardened under water. The concrete
must be dried before the test.

- Very high values for compressive strength (> 70 N/mm2)
can be achieved by adding pulverized fuel ash or silica.
However, these strengths cannot reliably be ascertained
using the concrete test hammer.

20 Appendix © 2001 PROCEQ SA

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© 2001 PROCEQ SA Appendix 21

The relationship between the rebound value R and the
compressive strength of the concrete fck is determined
using test specimens of a certain type of concrete.
Proceed as follows:

• Take test specimens following the regulations applying
in the particular country.

• In a pressure testing machine, apply force on the test
specimens with a force of 40 kN, vertical to the direc­tion in which the concrete was poured.

• Then measure the rebound hardness by applying as
many test impacts as possible to the sides of the test
specimen.

The only way to achieve a meaningful result is to measu­re the rebound values R and the compressive strength of
several test specimens.

Concrete is a very inhomogeneous material.
Test specimens made from the same batch of
concrete and stored together can reveal
discrepancies of ± 15 % when tested in the
pressure testing machine.

• Take the mean value Rm.

• Determine the compressive strength of the concrete by
applying force to the test specimens using the pres­sure testing machine, until the test specimens break.
Then ascertain the mean value fckm.

The pair of values Rm/ fckm applies to a certain range
of the measured rebound value R.

It is necessary to test samples of differing qualities and /
or ages in order to prepare a new conversion curve for
the entire range of rebound values from R = 20 to R = 55.

• Using the pairs of values Rm/ fckm, calculate the
mathematical shape of the conversion curve, i.e. deter­mine the parameters a, b and c of the x2function (e.g.
EXCEL in the RGP function).

8.4 Determining Time Coefficient

The age of the concrete and its carbonate penetration
depth can significantly increase the measured rebound
values R.
It is possible to obtain accurate values for the effective
strength by removing the hard, carbonate-impregnated sur­face layer using a manual grinding machine over a surface
area of about Ø 120 mm and performing the measurement
on the non-carbonate-impregnated concrete.
The time coefficient, i.e. the measurement of the increased
rebound values R, can be ascertained by taking additional
measurements on the carbonate-impregnated surface.

R

m carb.

: Average rebound value R, measured on

carbonate-impregnated concrete surface

R

m n.c.

: Average rebound value R, measured on

non-carbonate-impregnated concrete
surface

R

m carb.

R

m carb.

Time coeff. Zf= ⇒ R

m n.c.

=

R

m n.c.

Z

f

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