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THE USE OF COMBINED NON DESTRUCTIVE
TESTING IN THE CONCRETE STRENGHT ASSESSMENT FROM
LABORATORY SPECIMENS AND EXISTING BUILDINGS
1 2 3 4 5
Mulik Nikhil V. , BalkiMinal R. , Chhabria Deep S. , Ghare Vijay D. , Tele Vishal S. ,
6
Mrs. Patil Shweta .
Department Of Civil Engineering, Genba Sopanrao Moze College of Engineering, Balewadi, Pune
University Of Pune, Maharashtra, India
Asst. Prof. in Civil Engineering
Department Of Civil Engineering, Genba Sopanrao Moze College of Engineering, Balewadi, Pune
University Of Pune, Maharashtra, India
1 2 3
Email: nikhil152594@gmail.com, balkiminal333@gmail.com, dchhabria57@yahoo.in,
6Sapatil60@rediffmail.com
Abstract: -Non Destructive Testing (NDT) as From this exhaustive and extensive
the name implies refers to a test that does not experimental work it was found that SonReb
impair the intended performance of the method, combining Schmidt rebound hammer
element, member or structure under and Ultrasonic Pulse Velocity methods, allows
investigation.In this paper a series of non- compensating the limits and the uncertainty
destructive tests has been performed with the typical of each method. The use of the combined
purpose to investigate on the mechanical methods (SonReb) increases the accuracy of the
properties of the concrete employed in the civil estimation of the in situ concrete compressive
buildings. strength.
A series of specimens were prepared in order to The research aims on the rehabilitation of
correlate the “in situ” concrete strengths reinforced concrete buildings that begin to
obtained by combined non-destructive method show signs of decay and deterioration.
with the cubical strength obtained by Keywords: - Concrete, Concrete compressive
destructive methods. The combined method strength, Non-destructive investigations,
(SonReb Method) was used to quality control Combined Methods, SonReb Methods.
and strength estimation of the concrete.This I. INTRODUCTION
combined method requires short time to obtain Concrete has been most widely used as
the results, it’s a non-invasive method and it construction material for over 100 years, because
does not affect the resistance of structural it is strong in compression. The evaluation of the
elements. concrete compressive strength is a fundamental
Finally the investigation and comparison of step for assessment of existing reinforced concrete
experimental results of non-destructive tests building according to the last seismic codes. This
and cubical strength with the help of statistical valuation can be conducted by the use of both
data obtained by testing of specimen as per destructive and non-destructive method. Through
recommended procedures by IS 13311:1992 the concrete compressive strength, other concrete
and IS 516:1959 respectively.
ISSN (PRINT): 2393-8374, (ONLINE): 2394-0697, VOLUME-2, ISSUE-5, 2015
55
INTERNATIONAL JOURNAL OF CURRENT ENGINEERING AND SCIENTIFIC RESEARCH (IJCESR)
properties like elastic modulus, tensile strength the tray followed by crushed sand, and then
and durability can be obtained. cement. The materials were dry mixed thoroughly
Service life of concrete is found to be limiting in for 1 min.before adding water.Mixing continued
various environmental degrading factors as it is for further few minutes after adding
exposed to it. This therefore has brought about the water.Concrete was then placed in IS specified
need for test method to measure the in-place moulds in three layers, each layer was being
properties of concrete for quality assurance and for
evaluation of existing conditions. Since such test compacted by standard tamping road with more
are expected as non-impairing the function of the than 35 strokes.Exposed surface was finished with
structure and allow for re-testing at the same trowel to avoid uneven surface.
location to evaluate the changes in property at A total of 60 concrete specimens 150x150x150mm
some other point in time, these methods should be was designed and fabricated.Specimens were
non-destructive. prepared to obtain characteristic cube strength of
The combination of several techniques of non- 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa and
destructive testing is often used empirically, 40 MPa. In particular, 10 specimens of each grade.
combining two techniques mostly used to enhance Specimens were cured by immersing them in
the reliability of the estimate compressive strength curing tank for 28 days.
of concrete; the principle is based on correlations
between observed measurements and the desired TABLE 1
property.The standardized combine method and MIX PROPORTION AND CONCRETE BATCH
the most widely used internationally is SonReb Cemen Aggregate Wate
3
method. First born and established in Romania Grade t (kg/m ) r
then developed in Australia and in Europe.The 3 Coar (lit/m3
(kg/m ) Fine se )
best approach is generally to develop a M15 270 711 1460 135
relationship of correlation between the Ultra Sonic M20 320 794 1138 176
Pulse Velocity, the index of rebound hammer and M25 340 775 1112 185
the compressive strength of standardized M30 380 760 1090 187
laboratory specimen. M35 410 735 1053 200
II. TEST SPECIMEN M40 430 718 1030 185
A. Materials used
[1] Cement: Ordinary Portland cement (OPC) of 53 III. TEST PROGRAM
grade of Birla Super Cement is used in this A. Rebound Hammer test on cubes
experimental work. Weight of each cement bag The Schmidt rebound hammer is
is 50 kg. principally a surface hardness tester, which works
[2] Fine aggregates: Crushed sand having specific on the principle that the rebound of an elastic mass
gravity 2.77gm/cc and Fineness modulus as depends on the hardness of the surface against
3.15 which the mass impinges. There is seemingly
[3] Coarse aggregate: Consist of 10 mm and 20 theoretical relationship between the strength of
mm crushed aggregate. 10 mm aggregate concrete and the rebound number of the hammer.
having specific gravity 2.91gm/cc and FM as The weight of the Schmidt rebound
2.012. 20mm aggregate having specific gravity hammer is about 1.8 kg and is suitable for both
2.88gm/cc and FM as 2.1. laboratory and field purpose. The rebound distance
of the hammer mass is measured on an arbitrary
B. Mix proportion and casting procedure scale ranging from 10 to 100. The rebound
Hand mixing over a mixing tray was done distance of the hammer is recorded as a “rebound
throughout. Coarse aggregates were placed first in number” corresponding to the position of the rider
on the scale.
ISSN (PRINT): 2393-8374, (ONLINE): 2394-0697, VOLUME-2, ISSUE-5, 2015
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INTERNATIONAL JOURNAL OF CURRENT ENGINEERING AND SCIENTIFIC RESEARCH (IJCESR)
TABLE 2 to calculate crushing strength of concrete
HARDNESS CRITERIA FOR CONCRETE according to IS: 516-1959.
QUALITY GRADING (IS 13311 (PART The measuring strength of specimen is
2):1992) calculated by dividing the maximum load applied
Average Rebound Quality to the specimen during the test by the cross section
Number area.
Above 40 Very Good Hard D. Calculation
Concrete The compressive strength of the specimen shall
30 - 40 Good Concrete be expressed as fck.
20 - 30 Fair Concrete In the case of the SonReb method the law of
Below 20 Poor Concrete correlation among compressive strength, Rebound
B. Ultrasonic Pulse Velocity test on cubes Hammer index and ultrasonic velocity can be
The equipment consists basically of an electrical expressed as (Pucinotti 2005):
b c
pulse generator, a pair of transducers, an amplifier fck= a . V . R … (i)
and an electronic timing device for measuring the where,
time interval between the initiation of a pulse a, b, c are constants
generated at the transmitting transducer and its V - Ultrasonic Pulse Velocity
arrival at the receiving transducer. R - Rebound Number
Pulse velocity (in km/s or m/s) is given by: IV. RESULT AND DISCUSSION
࢜ൌࡸ Among the obtained 60 results of Rebound
where, ࢀ Hammer, Ultrasonic Pulse Velocity and
v is the longitudinal pulse velocity, Compression testing, 20 random results are
L is the path length, selected to obtain a, b and c constants.
T is the time taken by the pulse to travel path TABLE 4
length. RESULTS
TABLE 3 Compressive
CONCRETE QUALITY GRADING USING R UPV Strength by
VELOCITY CRITERION (IS 13311 (PART CTM
1):1992) 23 3620 16.8
Pulse Velocity 24.8 3718 17.4
km/sec ft/sec Quality 25.2 3906 18.1
> 4.5 > 15 Excellent 26.8 3789 19.6
3.5 – 4.5 12 – 15 Good 27.6 4003 20.1
3.0 – 3.5 10 – 12 Doubtful 27.4 4112 20.5
2.0 – 3.0 7 – 10 Poor 29.6 3964 21.4
< 2.0 < 7 Very Poor 31.8 4003 23.8
33 3998 25.6
C. Compression testing of cubes 32.2 4112 26.9
Compression testing machine of capacity 2000 kN 29.2 4049 28.9
is used for compression testing of cube as casted 29.8 4109 29.6
of size 150 x 150 x 150 mm and capable of giving 30.4 4112 30.3
load at the rate of 140 kg/sq.cm/min. Testing of the 32.4 4129 31.2
concrete cubes is tested under CTM at the age of 31.2 4219 32.4
28 days. The wet cubes were placed in the machine 31.8 4199 33.1
between wiped and cleaned loading surfaces and 33.6 4112 35.8
load is given approximately at the rate of 140 34.2 4159 36.9
kg/sq.cm/min. and ultimate crushing load is noted 35.8 4259 38.4
39.8 4159 40.2
ISSN (PRINT): 2393-8374, (ONLINE): 2394-0697, VOLUME-2, ISSUE-5, 2015
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INTERNATIONAL JOURNAL OF CURRENT ENGINEERING AND SCIENTIFIC RESEARCH (IJCESR)
So the question is how to determine the constants E 45
T
a, b and c from the data.The LINEST function of E 40
R
EXCEL can be used to do this. C 35
CON
30
OF
The a, b and c obtained are: H 25
T
NG20
E
R 15
a = 1.64111E-09 ST
E
b = 2.293662304 V 10
c = 1.30768373 SSI5
MPRE0
So the law of correlation among CO 01020304050
compressive strength, Rebound Hammer index REBOUND HAMMER INDICES
and ultrasonic velocity for this set of data would Fig. 1 Relationship of Rebound Hammer vs
be: Compressive Strength
f 2.293662304 1.30768373 y = 1.6516x - 22.991
ck= (1.64111E-09) . V . R …
(ii) Accuracy obtained 0.798
TABLE 5 ii. When using the ultrasonic pulse velocity
COMPRESSIVE STRENGTH BY SONREB for strength estimation, a correlation
USING FORMULA (ii) coefficient of 0.672 is achieved.
fck
(SONREB)
14.3987 E45
16.8936 RET40
C35
19.3173 N
CO
30
OF
19.526 25
H
23.0169 20
24.2481 STRENGT15
10
E
24.6619 V 5
SSI
E
27.7009 R 0
MP 3400 3600 3800 4000 4200 4400
O
28.9925 C ULTRA SONIC PULSE VELOCITY
29.9471 Fig.2 Relationship of Ultrasonic Pulse Velocity
25.4351 vs Compressive Strength
27.017
27.777 y =0.0362x - 118.57
30.4776 Accuracy obtained 0.6724
30.4808
30.9108 iii. In comparison, combining the two methods
31.661 by using the SONREB data gives a
33.2581 significantly highercorrelation coefficient
37.2848 of 0.867 as we have seen.
40.5525
By using the above data, we can also see
the effectiveness of the SonReb method.
i. Simply using the rebound values alone for
strength estimation, a correlation
coefficient of 0.798 is achieved.
ISSN (PRINT): 2393-8374, (ONLINE): 2394-0697, VOLUME-2, ISSUE-5, 2015
58
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