Page 1
OPERATION MANUAL
Sino Age Development Techtrade Ltd.
-
User Manual
Surface Testing PCE-HT-225A
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03
Table of contents
Chapter1 - General Description ........................................................................................................... 4
1.1. Applications ....................................................................................................................... 4
1.2. Basic principle ................................................................................................................... 4
1.3. Structure of Concrete Test Hammer .................................................................................. 4
1.4. Main technical specifications ............................................................................................ 5
Chapter2 - Operating and Testing Methods of Concrete Test Hammer .............................................. 6
2.1. Operating method of Concrete Test Hammer ................................................................... 6
2.2. Testing method of Concrete Hammer ............................................................................... 7
2.2.1. Preparatory process of test ................................................................................................ 7
2.2.2. Rules for resilience test ..................................................................................................... 8
2.2.3. Determination of carburized depth .................................................................................. 10
Chapter3 - Processing of test data ..................................................................................................... 12
3.1. Calculation of resilience value ........................................................................................ 12
3.2. Calculation of carburized depth ...................................................................................... 14
3.3. Evaluation of concrete strength ....................................................................................... 14
Chapter4 - Maintenance of Concrete Test Hammer .......................................................................... 17
Appendix 1 - Common faults of the Concrete Test Hammer and the analysis on their causes ......... 18
Appendix 2 - Conversion table of concrete strength value of test zone ............................................. 20
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04
Chapter 1 - General Description
1.1. Applications
With the merits of simple structure, easy correction, maintenance and repair, and
portability, the Concrete Test Hammer is widely used in civil engineering and
construction industry for testing the strength of concrete. Compared to other
nondestructive testers, the Concrete Test Hammer is an economical and practical
nondestructive testing instrument.
HT-225A is a medium Concrete Test Hammer, its kinetic energy of impact is
2．207J(0.225kgfm)．It is extensively used for testing the strength of various concrete
members (slab, beam, column) of normal building strength and bridge.
1.2. Basic principle
When testing the strength of concrete, Concrete Hammer uses a certain elastic force to
transit the impact force of an impact hammer to the surface of concrete, its initial
kinetic energy redistributes, a part of energy in the form of plastic deformation or
residual deformation is absorbed by the concrete, and another part of energy which is
proportional to the surface hardness is transmitted to the impact hammer, making the
hammer resile to a certain height, then the strength of the concrete is derived from the
proportional relation between the height of resilience and the concrete strength．
1.3. Structure of Concrete Test Hammer
The Concrete Test Hammer is mainly composed of flip system, value-indicating
system and shell component．Its structure is shown in Fig．1． The diagram shows the
state that the impact hammer has finished impact in the test and the pushbutton has
locked the movement，ie．retaining state of resilience value．
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05
1．Flip rod
2．Test surface
3．Shell
4．Pointer block
5．Dividing rule
6．Pushbutton
7．Center guide rod
8．Guide flange
9．Cap
10．Clasp
11．Tail hood
12．Pressure spring
13．Hanger
14．Impact hammer
15．Buffer pressure spring
16．Flip tension spring
17．Tension spring seat
18．Felt ring
19．Bolt
20．Nut
21．Pointer piece
22．Pointer shaft
23．Hanger
24．Hanger dowel
Fig(1)
1.4. Main technical specifications
The main performance indicators of HT-225A Concrete Test Hammer are as follows：
1) Nominal kinetic energy: 2.207J(0.225kgfm)
2) Mean value of steel-anvil ratings of Concrete Test Hammer: 80±2
3) Overall dimension: φ66×280mm
4) Weight: 1kg
5) Test thickness: ＜70cm
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06
Chapter 2 - Operating and Testing Methods of
Concrete Test Hammer
2.1. Operating method of Concrete Test Hammer
To use and operate the correctly can give better play to its efficiency and improve the
accuracy of test．Therefore, the operating personnel of the instrument must carry out
operation according to the stipulated operating rules and requirement．In the whole
process of the instrument, it is necessary to pay attention to the correct gesture of
holding the instrument．The correct gesture of holding the instrument is that one hand
holds the middle portion of the instrument, and which also plays the function of
straightening up in the whole process；another hand holds and presses the tail hood of
the instrument, and which is mainly for exerting pressure on the instrument while also
playing the auxiliary function of straightening up．
The basic points of the operation of the Concrete Test Hammer are that the force used
must be even and slow, the Concrete Test Hammer should be straightened up to
vertically aiming at the test surface, and should not be swayed．
The operating procedures of the Concrete Test Hammer are as follows：
2.1.1. Make the flip rod 1 of the Concrete Test Hammer press against the surface of concrete,
lightly press the tail hood 11 to make push-button 6 release guide flange 8, under the
action of pressure spring 12,the guide flange brings along the pointer block to move
downward to “0” position；at that time, hanger 13 links with the tail of impact hammer,
the flip rod extends out from the shell of instrument, then test can be carried out．
During this process of operation, when the pushbutton releases the guide flange, the
operator’s two hands should raise the Concrete Test Hammer to leave the test surface
of concrete which it originally pressed against, the speed of raising should be quick so
as to make it easier for the hanger to link with the impact hammer．
2.1.2. Maker the extended flip rod aiming at the test point of the test surface of the test
specimen of concrete and keep the center axis of the Concrete Test Hammer to be
perpendicular to the test surface；then use one hand to hold the instrument shell 3, and
other hand to slowly and evenly hold and press the tail hood 11, at that time flip
tension spring 16 is stretched, the flip rod is pressed into the instrument shell，i．e．the
impact hammer 14 obtains the energy from the flip tension spring.
When being pushed and pressed to a certain position, the back of hanger 13 touches the
bolt 19 on the tail hood, at that time flip tension spring should be stretched by 75mm,
the impact hammer 14 has obtained an energy of 2．207J specified by the design of the
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07
instrument, and is at position ready to be set off at a touch.
During this process of operation, care must be taken not to use too much strength to
result in an impact, and the center axis of the instrument should always be kept
perpendicular to the test surface without sway．
2.1.3. The impact hammer will be disconnected with the hanger when continuing to exert
pressure on the tail hood．Owing to the action of the flip tension spring 16，the impact
hammer rapidly impacts along the center guide rod 7 toward the flip rod 1, the kinetic
energy is transmitted to the concrete test specimen through the flip rod．
During this process of operation, the impact hammer collides with the flip rod many
times, therefore the operator must hold the Concrete Hammer firmly swaying, and
make the axis of the instrument keeping perpendicular to the test surface．
2.1.4. After resiling, the impact hammer brings the pointer block 4 to a certain position, then
the operator should continue holding and pressing the Concrete Hammer to keep the
flip rod against the test surface, and read from the dividing ruler the value N
corresponding to the dividing line on the pointer block 4．If the light is dim or it is
inconvenient to read, the operator can, after finishing flip, press down the pushbutton 6
to lock the guide flange, making the pointer block 4 keep in position, then take the
instrument to a place where it is convenient to observe, so as to read the value N and
make a record．
The above－mentioned is the whole process of one flip test and the operator can obtain
a resilience value, and by repeating this process the required resilience value of the test
point can be obtained．
2.2. Testing method of Concrete Hammer
To strictly execute the technical rules of Concrete Hammer and skillfully master the
testing technology of the Concrete Hammer, the basic performance and operating
method of the instrument are the prerequisites for smoothly carrying on the test of
strength by the resilience method．
As for the provinces and cities that have established regional resilience curves and the
regional technical rules of resilience method, they can also adopt regional curves or
execute regional rules．Those provinces and cities that have not established resilience
curves or rules should the＂Technical Rules for the Evaluation of Compression
Resistance of Concrete by Using JGJ123-85 resilience method＂．
2.2.1. Preparatory process of test
1) Selection of test zone
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08
In accordance with the requirement of technical rules of resilience methods, the
test zone should be selected on the representative member according to the quality
condition of the member．
A．The test zone should be selected on the lateral face of the concreting ( the side
of laid－on shutter board that is perpendicular to the concreting direction)．If it is
impossible to meet this requirement, it can be selected on the concreting surface or
bottom．
B．The test zone should be selected on the surface of the exposed part of the
member where it is easy to measure the resilience value and the carburized depth．
C．The test zone should be selected on the two basically symmetrical test surfaces
(hereinafter referred to test surface ) on two relative surfaces of the member．If it
is impossible to meet this requirement, it is allowed to have only one test surface．
D．The surface of test zone should be clean, flat and dry, and must not have joint,
finishing coat, rendering coat, laitance, oil stain, and voids and pits, the grinding
wheel provided with the machine can be used to clean the surface impurity
substances and polish the rough places if necessary, and the surface should not
have any residual powder or debris．
2) The number of test zones on every test member should be no less than 10, and
they should be evenly distributed on the test surface, and should bypass the
reinforcing bar and embedded iron parts within the concrete or set up nearby．
3) The spacing between two adjoining test zones should not be greater than 2m．
4) It is desirable that the size of test zone can hold 16 resilience test points, usually is
about 400cm2．
5) Test points should be evenly distributed within the scope of test zone, the spacing
between two adjoining test points should not be less than 3cm, the distance
between the test point and the edge of member or exposed reinforcing bar and iron
parts should not be less than 5cm．Test points should bypass reinforcing bar, air
hole and exposed stone．
2.2.2. Rules for resilience test
1) According to the standard condition of Concrete hammer, test the instrument and
it should measure up to the standard．
2) According to the technical rules of resilience method, select and arrange test zones,
test surfaces and test points and they should have clear numbering marks．
3) All the small－sized and low－rigidity members or those with the test location
less than 10cm thick, should be provided with support to fix it securely, then test
can be carried out．
4) If the test surface layer of the concrete has been wetted for a short term, test
should not be carried out until the surface layer is dried by air.
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09
5) Steam－cured concrete should not be tested until that the member has undergone a
natural curing for 14 days after being taken out from the curing pit．
6) The reading accuracy of the resilience value should be up to 1 in the test, and the
measured resilience value should be noted on the test record sheet．
7) Each test point can be tested only once, no repeated resiliences and tests on the
same point are allowed．
8) The two relative test surfaces of each test zone should be tested on 8 points each,
and 16 points in total．If tests can only be carried out on one test surface, then test
on 16 points should be carried out on that surface．(The test surface can be
expanded appropriately if permitted．)
9) To the nonhorizontally tested surface, the included angle between the center axis
of Concrete Test Hammer and the horizontal line should be determined, and the＂
+＂ or＂－＂angle value and the corresponding resilience value should be
noted．The positive and negative included angles are shown Fig．2．
10) When tests are carried out on concreting surface, the measured resilience values
should be noted with＂bottom＂,＂top＂or＂lateral face＂．
11) Whether the test surface is carburized or not should be timely judged, and should
be noted for the measured resilience value．
12) The dry and wet degree of the test surface should be judged and should be noted
with dry surface or wet surface and their respective resiliences values．
13) If the surface layer and the interior of the test location of the concrete are not of
the same quality and show obvious difference, or there are serious defects in
concrete, they are not suitable for resilience tests．
14) Concrete that has suffered chemical corrosion, fire, cold injury during hardening
period, high－temperature or humid environment for a long period of time or has
been impregnated with water is not suitable for resilience tests．
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10
Fig．2 Diagram of test angle α
15) When the ambient temperature is lower then 5℃ or higher than 35℃, it is not
suitable to carry out resilience tests．
16) If the radius of curvature of the test location is small than 23cm, it is not suitable
to carry out resilience tests．
2.2.3. Determination of carburized depth
Carburization is the main factor of affecting the test of concrete strength by resilience
method, therefore it is necessary to carry out the measurement of carburized depth
immediately after the resilience tests, and the measurement result should be taken as
the basis of the determination of concrete strength．The measuring method is as
follows：
1) Use a proper tool to make a hole of 15mm diameter in the location，the hole depth
is slightly greater than the carburized depth of the concrete．
2) Clean away powder and debris in the hole, but it is forbidden to wash by liquid．
3) After the cleaning, immediately drip 1% alcoholic phenothalin solution on the
hole wall．The uncarburized concrete will change color to a purplish red while the
carburized concrete will not change color．
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11
4) Use steel ruler to measure once or twice the vertical distance from the test surface
to the place on the hole wall where color is unchanged, the accuracy is to
0.5mm．That distance is the very carburized depth of that test zone．
5) For determination of the value of carburized depth, it is necessary to select one
test point for one test zone．If the concrete qualities or resilience values of two
adjoining test zones are basically similar, then the value of the adjoining
carburized depth can be used as representative．
Page 11
△Nα
Test angleα
－90O
+90O
+60O
+45O
+30O
－30O
－45O
－60O
20
－6．0
－5．0
－4．0
－3．0
+2．5
+3．0
+3．5
+4．5
30
－5．0
－4．0
－3．5
－2．5
+2．0
+2．5
+3．0
+3．5
12
Chapter 3 - Processing of test data
3.1. Calculation of resilience value
When the Concrete Test Hammer is used to test the lateral face of concreting in the
horizontal direction, the three greatest values and three smallest values in the 16
resilience values should be rejected, take the remaining 10 resilience values and
calculate the mean resilience value of the test zone by the following formula：
(1)
Where，N――mean resilience value of the test zone, the calculated value keeps valid
up to one digit after decimal point．
Ni――resilience value of the i test point．
When the Concrete Hammer is used to test the lateral face of concreting in
nonhorizontal direction, the measured data should data should be used first to calculate
the mean resilience value Nα of the test zone by formula (1) according to the angle α
between the axis of Concrete Hammer and the horizontal direction, then convert it by
the following formula into the mean resilience value of the test zone tested in
horizontal direction．
N=Nα＋△Ｎ
Where, N――mean resilience value of the test zone tested when the Concrete
Hammer and the horizontal direction are in an α angle, the calculated value keeps
valid up to one digit after decimal point．
Nα ―― the correction values of resilience values at different test angles consulted
from Table 1, the value keeps valid up to one digit after decimal point．
The correction values △Nα of resilience values tested in nonhorizontal state．
Correction values △Nαof resilience values at
different test angles α Tab．1
（2）
S
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40
-4.0
－3．5
-3.0
－2．0
+1．5
+2．0
+2．5
+3．0
50
-3.5
-3.0
-2.0
-1.5
+1．0
+1．5
+2．0
+2．5
Ns
△Ns
surface
bottom
20
＋2．5
－3．0
25
＋2．0
－2．5
30
＋1．5
－2．0
35
＋1．0
－1．5
40
＋0．5
－1．0
45
0
－0．5
50 0 0
13
Note：The △Nα correction values corresponding to Nα that have not been listed in
the table can be obtained by using interpolation, with an accuracy to one digit after
point．
When the Concrete Hammer is used to test the concreting surface or bottom in
nonhorizontal direction, they should be converted into the mean resilience value of the
test zone of the lateral face of concreting respectively according to the following
formula．
N=Ns+△Ns (3)
Where, Ns――the mean resilience value of the test zone of the concreting surface or
bottom, the calculated value keeps valid up to one digit after decimal point．
△Ns―― correction value of concreting surface or bottom, consulted from the table,
keeping valid up to one digit after decimal point．
Correction values of resilience values of different concreting surfaces．(See Tab．2)
Correction values △Ns of resilience values of
different test surfaces Tab．2
Note：
(1) The △Ns correction values corresponding to Ns that have not been listed in the
table can be obtained by using interpolation, with an accuracy to one digit after
decimal point．
(2) In the table, the correction values related to the concreting surface refer to the
correction values after ordinary mortar rendering．
(3) In the table, the correction values related to the concreting bottom refer to the
correction values under normal concreting condition when the surface and bottom of a
structure or a member adopt same kind of shuttering．
(4) In the test, if neither the Concrete Hammer is in horizontal direction nor the test
zone is the lateral face of concreting, an angle correction for the resilience value
should be carried out first , then the revision of concreting surface is carried out．
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3.2. Calculation of carburized depth
14
The mean value of carburized depth of each test zone should be calculated according
to the following formula：
(4)
Where, L――the mean value of carburized depth (mm) of the test zone, the calculated
value keeps valid up to one digit after decimal point．
Li――The value of carburized depth(mm) measured at i time；
n――Times of measurement of carburized depth of test zone．
If the mean value of carburized depth L calculated according to formula (4) is smaller
than or equal to 0．４ mm, then it should be treated as uncarburized, i．e．L is ≥ 6mm,
then it should be calculated according to a mean value of carburized depth L =6mm．
3.3. Evaluation of concrete strength
The determination of concrete strength can be divided into individual evaluation and
sampling evaluation．The usual sequence is as follows：first set the strength of test
zone, then the strength of test specimen, and then the strength of member and the
strength of the whole structure．On general condition, individual members are used as
the basic units for evaluating the strength of concrete．On the basis of evaluating the
strength of the sampled members respectively, the strength evaluation for whole
structure can be carried out．
Determination of the strength Rni of test zone
On the basis of the mean resilience value N of each test zone (after calculation and
correction, keep valid up to one digit after decimal point) and the mean carburized
depth L, find out the strength value Rni of the corresponding test zone by referring to
the data listed in the conversion table．The conversion table is seen in Appendix 2．
Determination of the strength Rn of test specimens
The mean strength value Rn of the concrete specimens should be calculated according
to the following formula：
(5)
Where, Rn――the mean strength value of the concrete specimen（MPa）,keeping valid
up to one digit after decimal point．
n――for the structure or member evaluated individually, take the number of test zone
of a test specimen；for structure or member evaluated by sampling, take the sum of the
numbers of the test zones of the sampled specimens．
Page 14
n
10～14
15～24
≥25
k
1．7
1．65
1．6
15
The strength values of the concrete specimens under the first condition and under the
second condition can be calculated according to the following formulas：
Rn1= 1．8 (Rn－KSn) (6)
Rn2= 1．8 (Rni) min (7)
Where , Rn1―― the strength value of the concrete specimen under first condition
（MPa）, accuracy keeping valid to one digit after decimal point．
Rn2―― the strength value of the concrete specimen under second condition (MPa),
accuracy keeping valid to one digit after decimal point．
Sn―― the strength standard difference of the concrete specimens (MPa), calculated
on formula (8), accuracy keeping valid to two digits after decimal point．
(8)
(Rni) min－For the structure or member evaluated individually, take the lowest
concrete strength value (MPa) in a test specimen of the test zone ；for the structure or
member evaluated by sampling, take the lowest concrete strength value (MPa) in every
sampled specimen of the test zone；
K－The acceptance coefficient values should be taken from Table 3；
n－For the structure or member evaluated individually, take the number of the test
zones of a test specimen；for the structure or member evaluated by sampling, take the
sum of the numbers of the test zones of the sampled specimens．
The acceptance coefficient values Tab．3
To determine the evaluated strength value of the concrete specimen, the following
rules should be observed：For the structure or member evaluated individually, take the
smaller value in formula (6) or (7)；for the structure or member evaluated by sampling,
take the smaller value in formula (6) or (7) in the sampled specimens．
The evaluation of the strength Rn of a structure or a member
The evaluated concrete strength value Rn of a structure or a member should be taken
according to the following rules．
1) Individual evaluation
For the structure or member evaluated individually, the evaluated strength value of the
concrete specimen is the very evaluated strength value of the concrete of an individual
structure or member．
2) Sampling evaluation
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16
For the structure or member evaluated by sampling, the evaluated strength value of the
concrete specimen is the very evaluated strength value of the concrete of the structure
or member equivalent to those in the same acceptance batch and with similar age and
under the same condition of production process．
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Chapter 4 - Maintenance of Concrete Test Hammer
To improve the testing accuracy of the resilience method, besides the correct operation
and use of instrument and the mastery of the testing technology, always keeping the
instrument in a sound and standard state is an important aspect．
Besides that the instrument should be used and kept by the specific personnel, the
following rules should be observed：
1) After use of the Concrete Test Hammer, it should be timely put into the leather
case to prevent dust from entering the interior of the instrument．
2) Do not dismantle and try the instrument ad lib, or its service life and accuracy will
be impaired．
3) The instrument should be maintained periodically．After is has been used for a
certain period of time, it should be wiped clean, but the assembling relation
between the parts and components and the whole machine should not be altered．
4) Except for doing the necessary steel－anvil rating, the instrument should be
avoided to try flip on substances that have a higher hardness than concrete．
Page 17
No．
State of faults
Analysis on causes
1
When concrete hammer flips in
test, the pointer block stays at the
starting position and will not
move．
The field angle of the pointer piece on pointer
block relative to pointer shaft is too small．
The pointer piece is fractured．
2
In the process of flipping, pointer
block sways and rises step by step．
The field angle of pointer piece on pointer
block is somewhat small．
The fitting between pointer block and pointer
shaft is too loose．
Pointer block touches and rubs with dividing
ruler locally or the local friction between
pointer block and the groove of machine shell
is too great．
3
Pointer block is carried up before
flipping, making reading
impossible．
The field angle of pointer piece on pointer
block is too large．
4
Impact hammer strikes too early．
he hook end of hanger has become a small
obtuse angle．
2．The tail end of impact hammer is locally
broken．
18
Appendix 1 - Common faults of the Concrete Test Hammer and the analysis
on their causes
Page 18
5
Incapable of flipping．
1．Hanger spring has dropped．
2．The hook end of hanger is fractured or has
become an obtuse angle owing to friction．
3 ． The flipping tension spring has been
fractured．
6
The flipping rod cannot extend out,
thus being useless．
Pushbutton will not act．
7
The flipping rod is easy dropping．
The fitting between the end of center guide
rod and the inner hole of flipping rod is not
tight．
8
The rated value of the instrument
in normal state is on the low side．
1．There are dirts on the impact plane of
impact hammer and flipping rod．
2．There are dirts between impact hammer and
center guide rod, so the friction has
augmented．
3．The contact of impact faces between impact
hammer and flipping rod is uneven．
4．Partial claw at the end of center guide rod is
fractured．
5．The movement is damaged．
19
Page 19
20
Rebound
value
MPa
Impact direction
Horizontal
Impact direction
90°
60°
45°
30°
0°
-30°
-45°
-60°
-90°
20
10.3
10.3
10.3
10.3
10.3
13.1
13.7
14.3
14.9
21
10.3
10.3
10.3
10.3
11.4
14.3
14.9
15.5
16.2
22
10.3
10.3
10.3
10.3
12.5
15.4
16.0
16.7
17.4
23
10.3
10.3
10.3
10.4
13.7
16.7
17.4
18.0
18.8
24
10.3
10.3
10.5
11.6
14.9
17.9
18.6
19.3
20.0
25
10.3
10.8
11.6
12.7
16.2
19.2
20.0
20.8
21.5
26
11.0
12.0
12.8
14.0
17.5
20.6
21.4
22.1
22.8
27
11.9
13.3
14.0
15.3
18.9
22.1
22.8
23.6
24.5
28
13.4
14.6
15.4
16.7
20.3
23.5
24.3
25.0
25.9
29
14.8
16.0
16.7
18.0
21.8
25.0
25.9
26.7
27.6
30
16.2
17.5
18.2
19.6
23.3
26.5
27.4
28.2
29.1
31
17.6
18.9
19.6
21.0
24.9
28.2
29.1
30.0
30.9
32
19.1
20.8
21.2
22.7
26.5
29.8
30.7
31.6
32.5
33
20.8
22.0
22.7
24.3
28.2
31.6
32.5
33.5
34.4
34
22.4
23.6
24.5
26.0
30.0
33.3
34.2
35.2
36.1
35
24.1
25.2
26.0
27.8
31.8
35.2
36.1
37.1
38.2
36
25.9
27.1
27.9
29.6
33.6
36.9
37.9
38.9
39.9
37
27.8
28.8
29.6
31.4
35.5
38.9
39.9
41.0
42.0
38
29.6
30.7
31.6
33.5
37.5
40.7
41.8
42.8
43.9
39
31.6
32.5
33.5
35.4
39.5
42.8
43.9
45.0
46.1
40
33.6
34.6
35.5
37.5
41.6
44.8
45.9
47.0
48.1
41
35.5
36.5
37.5
39.5
43.7
47.0
48.1
49.2
50.4
42
37.7
38.7
39.7
41.8
45.9
49.0
50.2
51.3
52.5
43
39.7
40.7
41.8
43.9
48.1
51.3
52.5
53.6
52.5
44
42.0
43.0
44.1
46.3
50.4
53.4
54.6
55.8
57.0
45
44.1
45.2
46.3
48.5
52.7
55.8
57.0
58.2
59.5
46
46.5
47.6
48.7
51.0
55.0
58.0
59.2
60.0
47
48.7
49.9
51.0
53.4
57.5
48
51.3
52.5
53.6
56.0
60.0
49
53.6
54.8
56.0
58.5
50
56.8
57.5
58.8
60.0
20
Appendix 2 - Conversion table of concrete strength value of test zone
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