Manual of Motar Test
Hammer HT-20
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User Manual for HT-20 Test Hammer
Directory
One
Usage scope….…………………….……………………………………2
Two
Technical specifications………….………………………………..2
Three
Structure principle ……………….…………………………………2
Four
Standard conditions……………….……………………………………3
Five
Operational procedures ……….……………………………… 4
Six
Seven
Calibration…………………………….…………………………………5
Maintain ………………………… .………………………… .……6
Eight
Testing technologies ……………………….…………………………7
Nine
Appendix … … … … … … … …
…………………………………9
User Manual for HT-20 Test Hammer
One
Usage scope
This instrument is applied to determine the compressive strength of mortar in
industrial and civil buildings
Measuring range is 1.0-25Mpa.
Two
Technical specifications
Technical parameters of HT-20 test hammer are as follows:
1. Impact energy: 0.196J（0.02kgf.m)
2. Tension spring stroke: 75mm
3. The static friction of pointer slider: 0.5±0.1N
4. Spherical radius of the head of rebound pole: 25mm
5. The average rebound values on steel anvil: 74±2
6. Housing dimensions: Φ54*268mm
7. Weight: ≈1Kg
Three
Structure principle
By researching the relationships between the compressive strength of mortar surface
and the rebound values, we can establish a test curve to determine mortar quality and
convenient our testing work.
HT-20 test hammer is composed of rebound system, data display system and shell
parts. Section view as Figure 1.
User Manual for HT-20 Test Hammer
Figure 1 section view
Four
Standard status
A test hammer in standard status can give a precise test value, before a testing, we
must sure that the instrument in this status, the status as below:
User Manual for HT-20 Test Hammer
1. Impact energy (standard, level direction)： 0.196J (0.02kgf．m)
2. impact stroke: 75mm
3. Work length of impact spring ( free status): 61.5 ±0.5mm
4. Maximum static friction force between pointer slider and axis: 0.4-0.6N
5. Spherical radius of the head of impact pole is: SR=25mm
6. Calibrate test hammer on steel anvil of HRC60± 2, the rebound values should be
Rm=74± 2. When calibrating, rotate impact pole head each five time test, and
average the rebound values.
Five
Operation
Good operation can improve the testing accuracy. Operation as follows：
Step 1. Generally, test hammer was locked during storage, we should unlock it
before a test. Take out test hammer, keeping the rebound pole perpendicular to a
surface (any hard). Pushing test hammer on end cover slowly, the hammer will unlock
and the button will bound out, stop pushing, removing the test hammer away from the
surface, rebound pole will reach out, and at the same time the rebound hammer will
be hooked because of the pushing from compression spring, now it’s ready for a test.
Step 2. Aim at test point, keep perpendicular, push slowly, rebound pole will be
pushed into the test hammer, at the same time, the compressing spring get compressed,
but the tension spring get stretch and uptight, keep pushing till rebound hammer
unhook, the rebound hammer will impact rebound pole by the pulling from tension
spring. After impact with rebound pole, the rebound hammer will be rebounded and
take the pointer up; the pointer will stop at the highest position, and we can know the
position by the gauge, each position against a value that is rebound value. Note that
before you record the rebound value DO NOT loose your hand, or the pointer will
ZERO SET automatically by the push from the compression spring.
Note: If it is difficult to read the data in rayless conditions specified in Step 2,
lock hammer by PRESS THE BUTTON ONLY AFTER IMPACT and remove
User Manual for HT-20 Test Hammer
the device to a convenient place in order to read the gauge. And unlock it by step
1 after reading for another test.
Step 3. Continue test at other test points.
Step 4. End of the test, push the rebound pole back into the test hammer, just like
above test procedure. After the rebound hammer impact, press the button and the test
hammer will be lock. Then clear it and put back suitcase.
Six
Calibration
In order to make sure our test hammer in a good work status, or keep the test accuracy,
we should calibrate test hammer regularly.
1. General calibration
Calibrating test hammer by a steel anvil, also called calibrate anvil, for HT20 test
hammer, impact energy is 0.196J, we can calibrate it on a anvil with HRC 60±2, such
as JW225 anvil. Refer to figure 2.
The calibrating is easy, just operate test hammer on anvil for some times, see if the
test value (calibrate value) in the range of 74±2, if it is, we can say that the test
hammer is good for a test.
Generally, we should calibrate test hammer each operate 2000 time, in a busy
testing day, we should calibrate it every day.
Test hammer
Steel anvil
Figure 2 calibrate test hammer
User Manual for HT-20 Test Hammer
2. Standard status calibration
This professional calibration needs inspect every component and the interactions
between them, following cases need this calibration.
1) Updating or changing of parts, especial the impact system or scale system..
2) After used too long time, for example 1 year.
3) The adjustment bolt of end cap is loose.
4) Operation more than 8,000 times.
5) Dropped from high place or other severe damage.
If customer didn’t equipped with professional person for inspecting test hammer,
you can send test hammer to inspection organization for calibrating, or send to us.
Seven
Maintain
Maintaining is absolutely necessary for keeping test hammer in a good status and with
good accuracy, besides only trained or skilled person should operate test hammer,
following are recommend too.
1. Test hammer should be put back package after using to keep from dust..
2. Do not detach device if not necessary in case affect its accuracy..
3. Test hammer needs maintain, clean it, but any way, do not change parts dimensions.
4. The friction of pointer slider should be fixed, and not allow lubricate oil, test the
friction with a meter, its normal friction should be in 0.4~0.6N.
Remarks:
Detachment and assembling procedures
Making test hammer against hard place, push end cover till the button loose, stop
pushing and let rebound pole reach out of the device slowly.
Screw off end cover and take out the compression spring, screw off the cover
cap, detach the semicircular clasp.
Keep the device upright (the rebound pole downwards), move the core
component to tail, hold the hook and unhook the rebound hammer, take out the core
component. Note it must be unhook firstly when you take it out or set it back.
User Manual for HT-20 Test Hammer
Detach the core component, impact rebound pole lightly by rebound hammer,
rebound pole will leave from the center rod, don’t miss the buffer spring. In general
situation, the three components, rebound hammer, tension spring and spring base
shouldn’t be detached, in case the tension spring transformation.
Screw pointer pole by opener from the end of the instrument, the pointer pole
will separate from the front fixer, keeping screwing till pointer pole separate from
pointer slider.
Generally, we don’t have to detach the gauge..
Above are detachment procedures, assembling procedures are opposite against above.
Of course calibration on steel anvil is indispensable at the end of all rectification and
assembling, test values should be Rm=74±2.
Eight Testing technologies
1. Before testing, customer and operator should learn testing regulation (different
country maybe different) and follow it in later testing work..
2. Reference technologies
a. Choose representative load bearing wall, need the surface easy to operate testing
and measure carbonization depth, avoid window and door and areas that metal in it.
b. Test area should be clear and dry, if decorative sheet on it, clear it away by the
millstone equipped with test hammer.
c. We should choose at least 10 test areas in a wall, in case there is a big deviation in
test values, for example 30%, we should increase areas to improve accuracy.
d. For a wall, each 15~20m2 we can choose 1 test area, at most 2. Generally, a test
area is 0.2-0.3m2
e. 12 test points in each test area, interval is about 20mm, each test point will be
User Manual for HT-20 Test Hammer
attacked 3 time, pick the last one (the third time) as test data.
f. test points should be spread average, avoid air hole and loose area.
3. Calculation
After the testing, we will get 12 data, wipe off the max and the min data, 10 left, and
average them and get the final rebound value Rm. For a test, if necessary we should
consider about the carbonization depth in calculation.
User Manual for HT-20 Test Hammer
Nine
Average rebound
value
Rm
strength
(Mpa)
Appendix
Average rebound
value
Rm
strength
(Mpa)
Average rebound
value
Rm
strength
(Mpa)
15.0
1.4
22.4
5.7
29.8
15.7
15.2
1.4
22.6
5.9
30.0
16.1
15.4
1.5
22.8
6.0
30.2
16.5
15.6
1.6
23.0
6.2
30.4
16.9
15.8
1.6
23.2
6.4
30.6
17.3
16.0
1.7
23.4
6.6
30.8
17.7
16.2
1.8
23.6
6.8
31.0
18.1
16.4
1.9
23.8
7.0
31.2
18.5
16.6
1.9
24.0
7.3
31.4
18.9
16.8
2.0
24.2
7.5
31.6
19.4
17.0
2.1
24.4
7.7
31.8
19.8
17.2
2.3
24.6
7.9
32.0
20.3
17.4
2.3
24.8
8.2
32.2
20.7
17.6
2.4
25.0
8.4
32.4
21.2
17.8
2.5
25.2
8.6
32.6
21.6
18.0
2.6
25.4
8.9
32.8
22.1
18.2
2.7
25.6
9.1
33.0
22.6
18.4
2.8
25.8
9.4
33.2
23.1
18.6
2.9
26.0
9.7
33.4
23.6
18.8
3.0
26.2
9.9
33.6
24.1
19.0
3.2
26.4
10.2
33.8
24.6
19.2
3.3
26.6
10.5
34.0
19.4
3.4
26.8
10.8
34.2
19.6
3.5
27.0
11.0
34.4
19.8
3.7
27.2
11.3
34.6
20.0
3.8
27.4
11.6
34.8
20.2
3.9
27.6
11.9
35.0
20.4
4.1
27.8
12.3
20.6
4.2
28.0
12.6
20.8
4.4
28.2
12.9
21.0
4.5
28.4
13.2
21.2
4.7
28.6
13.6
21.4
4.8
28.8
13.9
21.6
5.0
29.0
14.3
21.8
5.1
29.2
14.6
22.0
5.3
29.4
15.0
22.2
5.5
29.6
15.3