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Monitoring freshly poured concrete using ultrasonic waves guided

through reinforcing bars

Shruti Sharma a,⇑, Abhijit Mukherjee b

a Department of Civil Engineering, Thapar University, Patiala, Indiab Department of Civil Engineering, Curtin University, Bentley, WA 6102, Australia

a r t i c l e i n f o

 Article history:

Received 27 September 2013

Received in revised form 2 August 2014

Accepted 15 September 2014

Available online 12 October 2014

Keywords:

Guided waves

Ultrasonic

Longitudinal waves

Freshly poured concrete

Compressive strength

Pullout strength

a b s t r a c t

Durability and strength of mature concrete can be judged a great deal from its properties when it is

freshly poured. This paper demonstrates an ultrasonic in-situ monitoring technique for freshly poured

concrete. The solidification and curing of freshly poured concrete is monitored through the propagation

of ultrasonic waves in waveguides such as steel reinforcing bars. As concrete solidifies and cures, more

wave energy escapes into the surrounding concrete resulting in signal attenuation. RC beam specimens

are monitored with carefully selected ultrasonic signal patterns during the first 24 h of setting of con-

crete. Destructive tests such as bar pull out and compressive strength are also performed at different

stages of setting of concrete. The ultrasonic signals have been calibrated for determination of early age

concrete properties.

 2014 Elsevier Ltd. All rights reserved.

1. Introduction

In-situ concrete that is poured at site into a formwork where it

sets and becomes solid offers great flexibility of creating structures

in various aesthetically pleasing shapes with fewer joints.

However, it is challenging to consistently achieve the laid down

quality parameters. Modern day concrete that has to satisfy a num-

ber of rather demanding performance parameters uses many

admixtures that are sometimes not compatible. Thus, it is more

susceptible to deficiencies that may show up at a later stage.

Monitoring the early age characteristics of freshly poured concrete

when it transforms from fluid to solid can be an effective tool for

predicting its future performance.

At the time of pouring, concrete mix must easily flow into the

formwork. Once placed, calcium silicate hydrate formation leads

to hardening of concrete and the reaction may continue up to a

few years. Monitoring the rate of hardening at an early stage, one

can determine the time of removal of formwork and finally the

time when the structure can take the design load and serve its

intended purpose. More importantly, such monitoring can detect

anomalies at an early age and can facilitate easy removal of defec-

tive concrete e.g. by washing and avoid the hardship of removing

solidified concrete later. Hence, it is extremely important to set

performance parameters for freshly poured concrete and monitor

them in-situ. Conventional methods for monitoring freshly poured

concrete include slump cone test, flow table test, penetration nee-

dle test, hydration temperature measurement and pull-out test.

They are more suitable for laboratory applications. Rheological

testing methods that use different types of viscometers apply shear

force on fresh concrete that destroys the microstructure in the

early ages of hydration process. A non-destructive and in-situ tech-

nique for monitoring solidification of freshly poured concrete can

be of great help.

Ultrasonic wave propagation offers an exciting way of monitor-

ing the solidification of concrete [1]. Velocity of ultrasonic pulses

through a material increases as it solidifies. Thus, time taken by

it to traverse through the depth of concrete is proportional to the

degree of solidification   [2]. Based on this approach, ultrasound

and acoustic pulse velocity experiments have been reported for

characterizing the setting and early hydration of cement based

materials   [3–10]. More recently, the ultrasonic wave reflection

method has been reported in monitoring the setting behavior of 

concrete [11,12]. The reflection technique can use a single trans-

ducer that acts both as transmitter and receiver. Thus, the tech-

nique needs to access concrete at only one surface. The method

has been applied to study the strength, elastic and stiffening prop-

erties of early age cement-based materials [13–15]. During the set-

ting of concrete longitudinal and shear waves can monitored for

variation in their velocities   [16],   resonant frequencies   [17,18],

http://dx.doi.org/10.1016/j.cemconcomp.2014.09.011

0958-9465/  2014 Elsevier Ltd. All rights reserved.

⇑ Corresponding author. Tel.: +91 09417829341.

E-mail address: shruti.sharma@thapar.edu (S. Sharma).

Cement & Concrete Composites 55 (2015) 337–347

Contents lists available at   ScienceDirect

Cement & Concrete Composites

j o u r n a l h o m e p a g e :   w w w . e l s e v i e r . c o m / l o c a t e / c e m c o n c o m p

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As concrete sets and hardens, the bond between the reinforcing

bar and the surrounding concrete improves. The improved bond

increases leakage of the energy of waves into the surrounding con-

crete and causes signal attenuation. Thus, variation in signal atten-

uation can be calibrated to the degree of setting of concrete. To test

this hypothesis, an experimental program has been undertaken.

3. Experimental investigations

Experiments have been undertaken simultaneously using the

conventional techniques and the present ultrasonic guided wave

method. The conventional method of measurement for the initial

setting period is penetration of needle. After the initial setting,

ultrasonic pulse velocity method has been used. For this purpose,

freshly mixed concrete having proportions of cement, sand and

stone aggregates as 1:1.5:2.9 was poured in a wooden 150 mm

cube mold. Water–cement ratio was kept at 0.45. An average

slump of 60–80 mm was observed. An ambient temperature of 

3 0 ± 2 C was noted throughout the experiment. The mold had

two circular cut outs at its sides to attach the ultrasonic transduc-

ers (Fig. 1). Care was taken to seal the edges of the cut outs to pre-

vent any leakage through them. After pouring concrete in the cube,

the needle penetration test and the pulse velocity (UPV) test were

conducted on it. For the needle penetration test a standard needle

of 1 mm diameter and mass of 300 g was dropped from a height of 

40 mm. The depth of penetration was measured using callipers. As

concrete sets the depth of penetration reduces gradually. This

Fig. 2.  Concrete beam specimen for Ultrasonic Pulse Transmission Testing (UPT).

Fig. 3.  Set-up for Ultrasonic Pulse Transmission Testing (UPT).

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method is effective in determining the initial setting time. After

that the penetration is negligible. The UPV test canmonitor the set-

ting process after that. A TICO ZI 10006 make UPV tester with

transducers of 54 KHz has been used. The time taken by the pulse

to traverse a distance of 150 mmthrough concrete is measured and

the velocity is calculated. The pulse velocity is proportional to the

elastic constant of concrete. Thus, it calibrates the hardening

behavior. Results of both tests are compared with that of the pres-

ent method.

 3.1. Samples for guided wave tests

Specimens of dimensions 150 mm 150 mm 300 mm were

prepared from the concrete described above. One 25 mm diameter

plain mild steel bar of 600 mm length was placed at the center of 

cross-section of the beam at the time of casting. The bar projected

out by 150 mm on each side of beam (Fig. 2). Although ribbed bars

that offer mechanical bonding between the bar and the concrete

are more popular in construction, in this investigation plain bars

were used to avoid such mechanical bonding and to observe how

concrete setting influences interfacial bond only. An ultrasonic

testing system consisting of a pulser–receiver device (DPR300, JSR Ultrasonics), ultrasonic transducers (Karl Deutsch), data acqui-

sition card (Aquiris, DC438 Dual-channel, 12-bit, 100 MHz, 200

MS/s, 4-M) and a display device was used (Fig. 3a). Guided longitu-

dinal waves were produced in the embedded bars by keeping the

transducers at the two ends of the bars. One transducer acts as

transmitter and the other acts as receiver. A coupling gel was used

to connect the bar with the transducers. The wooden holder

assembly was fabricated in such a way it maintained a steady pres-

sure between the transducers and the bar throughout the investi-

gations (Fig. 3b). The reliability of the device was ensured by

repeating the measurement. The excitation signal consisted of a

compressive spike pulse. The pulse transmitted at the other end

of the bar was recorded on the receiving transducer. The ultrasonic

signatures were taken as soon as concrete was poured into the

mold. For the first two hours readings were taken at 15 min inter-

val. Thereafter signatures were recorded at an interval of an hour

for 24 h.

 3.2. Selection of excitation modes

To decide the best modes of excitation, an analytical solutionfor

wave propagation modes through a 25 mm diameter mild steel bar

surrounded by infinite expanse of concrete is obtained   [36]. The

materials properties are given in   Table 1. The phase velocity

(Fig. 4a), group velocity (Fig. 4b) and attenuation characteristics

(Fig. 4c) have been plotted against frequencies. It is clear that if 

0.1 MHz transducer is used only  L(0,1) mode will be generated

with a low attenuation (Fig. 3c). Therefore, 0.1 MHz transducer

was selected. Each of the higher modes shows a plateau region

around the steel longitudinal bulk velocity line (Fig. 4a). At

1 MHz, L(0,7) mode shows a different pattern. It links the subse-

quent plateau regions together to form a single low leakage mode

that propagates close to the longitudinal bulk velocity of steel. The

plateau regions correspond to the points of maximum energy

velocity (Fig. 4b) and minimum attenuation (Fig. 4c). Hence, in

addition to   L(0,1) mode at 0.1 MHz, another transducer 1 MHz

was also selected. This mode exhibits global attenuation minima

of 22 dB/m and is the fastest propagating mode. The phase velocity

as obtained from dispersion curve at this frequency is 6 km/s. Pulse

transmission was monitored regularly until 24 h. The signals had

no significant variation beyond that time.

 3.3. Destructive tests

A correlation between the ultrasonic signals and the compres-

sive strength and bond strength of concrete is attempted. For this

purpose, samples were tested destructively at specified durations

after pouring. This exercise also allowed checking of repeatability

of the present experiment. The nomenclature of samples with

 Table 1

Material properties of steel & concrete used for modeling in Disperse.

S. no. Material property Steel Concrete

1 Modulus,  E  (GPa) 210 29.6

2 Density (q), (kg/m3) 7932 2200

3 Longitudinal Attenuation (db/m) 0.003 0.2

4 Shear attenuation (db/m) 0.008 0.5

5 Longitudinal velocity (m/s) 5960 4100

6 Shear velocity (m/s) 3260 2300

7 Poisson’s ratio 0.2865 0.27Fig. 4.  Dispersion curves for 25 mm diameter bar in infinite expanse of concrete.

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specified time after pouring is in Table 2. Non-destructive tests of 

Ultrasonic Pulse Transmission (UPT), penetration depth (D) and

UPV (V ) readings were taken throughout the duration. Pull out

strength of the bar and cube compressive strength was performed

immediately after the specified time of setting. A Universal Testing

Machine (UTM) was used to conduct the destructive tests on con-

crete specimens of different ages. The pull out strength of the inter-

face was determined by securing the specimen in a UTM and

gently applying a tensile force on the exposed end of the bar. To

ensure repeatability of results minimum three samples were tested

in each case.

4. Results and Discussions

4.1. Ultrasonic Pulse Transmission (UPT) investigations

Ultrasonic pulse transmission signals were recorded using the

selected modes. The test was conducted on the beam specimen

of size 150 mm 150 mm 300 mmwith an embedded mild steel

rod of 25 mm diameter and 600 mm length. A pulse transmission

signature i.e. Voltage–time signal is captured immediately after

pouring concrete in the mold (Fig. 5a and b) and then subsequent

signals are recorded at regular intervals.

Figs. 6 and 7 show the pulse transmission signatures recorded

at different times after pouring concrete in the mold using  L(0,7)

at 1 MHz and L(0,1) at 0.1 MHz respectively. From the signatures

obtained at different intervals, peak to peak voltage amplitudes

(pk–pk) of the signals are calculated. This pk–pk voltage amplitude

values are normalized with respect to input pulse amplitude

obtained from an oscilloscope. This is reported as pk–pk voltage

ratio (R). A plot of ‘R’ vs. age of concrete is plotted for both selected

modes of L(0,7) at 1 MHz (Fig. 8) and L(0,1) at 0.1 MHz respectively

(Fig. 9). From the signatures (Fig. 6) and the pk–pk voltage ratio

plot with increasing age of setting concrete (Fig. 8), it is seen that

with 1 MHz frequency and L(0,7) mode, no drastic change in volt-

age amplitude of the first transmitted and received signal (Travel

length = 600 mm) is observed throughout the 24 h of pouring con-

crete though minor change is observed in second transmitted sig-

nal (Travel length = 1200 mm) which is not measurable and of 

practical interest. But when setting concrete is monitored using

L(0,1) mode at 0.1 MHz (Figs. 7 and 9), the peak–peak voltage

amplitude of the received signals drops continuously with increas-

ing age of concrete and the signal attenuates. This mode is sensi-

tive to the interfacial changes. As the concrete sets, the bond

between the embedded rebar and the surrounding concrete

improves. It leads to increase in leakage of energy into the sur-

rounding concrete; thus, causing a drop in signal strength. Hence,

fall in transmitted signal strength with this low frequency mode

 Table 2

Specimens nomenclature.

Time after pouring (h) Sample nomenclature

3 S3

6 S6

12 S12

18 S18

24 S24

Fig. 5.  Ultrasonic pulse transmission signature.

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is a good measure of development of bond between the embedded

bar and the surrounding concrete and can characterize the setting

phenomenon of concrete.

The sensitivity of  L(0,1) at 0.1 MHz can be explained by com-

paring its energy distribution profile vis-à-vis that of  L(0,7) mode

at 1 MHz. The radial distribution of displacement and strain energy

density of  L(0,7) is concentrated mainly in the core area of the bar

and has negligible surface component (Fig. 10a). Hence, signal in

this mode is more sensitive to irregularities and deteriorations

inside the bar rather than its surface. On the other hand,   L(0,1)

at 0.1 MHz has significant surface component and is sensitive to

changes in interface characteristics like bond development due to

setting of concrete. Such a mode is referred to as surface seeking

mode and would be used for determining the setting pattern of freshly poured concrete using ultrasonic pulse transmission

(Fig. 10b). This experiment illustrates the importance of selecting

the right mode for ultrasonic monitoring of the setting process of 

concrete.

The phenomenon of setting of concrete is also observed by fall

in penetration depth (D) of the needle (Fig. 11). At the time of pour,

maximum penetration is observed. As concrete sets, D  reduces at a

fast pace until about 2 h (From 14 mm to3 mm depth). At this time

the concrete has reached its initial setting . In the UPT graph (Fig. 9)

this point is characterized by a sudden increase in slope of  R. The

fall in penetration slows down gradually and after 3.5 h it remains

practically unchanged. That is the time when concrete has solidi-

fied enough to hold its form. The needle test is no longer useful

but it is possible to continue the Ultrasonic Pulse Transmission(UPT) investigation through the concrete at this stage. From the

observed falling trends in UPT signals with the surface sensitive

mode and drop in penetration depths, the bond development pro-

cess between rebar and concrete can be explained as follows.

In the first 1½–2 h, voltage amplitudes remain steady in UPT (R

falls from 1 to 0.9) indicating slow development of bond between

the mild steel bar and the surrounding concrete (Fig. 9). It is also

well supported by penetration depth results. During this duration,

maximum fall in D is observed. It indicates that when concrete is in

fluid phase and the needle can penetrate easily, the bond between

rebar and concrete is still not appreciable. This corresponds to ‘Ini-

tial Setting of concrete’ and the zone is referred to as ‘Fluid Zone’.

From 2 to 18 h   R   drops from 0.9 to 0.1. It indicates gradual

development of bond between steel bars and embedding concrete.

It is an indicator of setting of the freshly poured concrete. It under-goes a change of phase from fluid to solid during this time or in

other words it is in phase transition. This can be classified as Final

Setting of Concrete. This time is characterized by hardly any

increase in D. This zone is referred as ‘Transition Zone’.

After 18 h R once again becomes steady and it falls from0.1 to 0,

indicating that solidification and setting of concrete has already

taken place. This Zone is referred to as ‘Solid Zone’. The rate of fall

of the transmitted signal strength using a specific low frequency

surface seeking guided wave mode can successfully indicate the

setting process of concrete. Transmitted signal strength can serve

as an excellent in-situ indicator of different stages of setting of 

concrete.

In order to check the repeatability and accuracy of the results,

specimens were cast in which UPT and penetration measurementswere recorded for different ages of setting of 3 h, 6 h, 12 h & 18 h

Fig. 6.  Pulse transmission signatures at different instants of pouring concrete using  L(0,7) mode at 1 MHz.

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(Figs. 12 and 13). It is clear from Fig. 12 that UPT signals followed

the same trend for all beams as inthe 24h beamspecimen. The3 h

and 6 h specimens have a more rapid fall than the others. However,

they had similar trends as the other specimens. On a close look it

was observed that the ambient temperature for those two speci-

mens was about 4 C higher than that for other specimens. As a

result, setting in these two specimens is more rapid than the oth-

ers. This is indicated by more rapid fall in  R. Thus, it may be con-cluded that the three distinct stages of concrete setting identified

earlier can be observed for a range of ambient temperatures. How-

ever, their length may vary depending on temperature.

Correlation between penetration depth and UPT values can also

be illustrated by plotting variation of  R  with D  (Fig. 14). It is clear

from the graph that it has a bilinear behavior. Initially when the

concrete is in fluid state, value of  R  is high and does not change

appreciably. The penetration depth, on the other hand, shows a

drastic fall from R0 to Ri. This is when the initial setting is achieved.

After the initial setting, as a result of concrete solidification, the

penetration depth gets steady and the bond starts to develop. As

a result,  R  reduces at a faster rate from this point until the finalsetting is reached. Thus, the discerning point between the initial

Fig. 7.  Pulse transmission signatures at different instants of pouring concrete using  L(0,1) mode at 0.1 MHz.

Fig. 8.  UPT monitoring with L(0,1) mode at 1 MHz.

Fig. 9.  UPT monitoring with  L(0,7) mode at 0.1MHz.

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setting stage and the final setting stage is a sudden fall in R. R in the

two stages can be calibrated with the penetration depth using a

pair of linear equations.

Dt  ¼  D0  fðD0  DiÞ=R0  RiÞgðR0  RÞ   whenR >  Ri   ð1Þ

Dt  ¼  Di  fðDi  D f Þ=Ri  R f ÞgðRi  RÞ   whenR >  Ri   ð2Þ

where

Dt  = penetration depth at any hour of pouring.

Di = penetration depth at initial set.

D f  = penetration depth at final set.

D0 = penetration depth at time t  = 0 h (immediately after pour-

ing concrete).

R0 = pk–pk voltage ratio at time t   = 0 h (immediately after pour-

ing concrete).

Ri = pk–pk voltage ratio at initial set.

R f  = pk–pk voltage ratio at final set.R = pk–pk voltage ratio at an instant.

Fig. 10.  Mode shapes of selected modes for UPT investigations.

Fig. 11.  Variation of penetration depth (D) after concrete pouring.

Fig. 12.  Variation of UPT signal strength at different ages of pouring concrete.

Fig. 13.  Variation of Penetration Depth (D) at different ages of pouring concrete.

Fig. 14.  Variation in pk–pk voltage ratio (R) vs. penetration depth (D).

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4.2. Comparison with UPV measurements

To compare the efficacy of the proposed ultrasonic guided

waves technique with the existing UPV method, Ultrasonic Pulse

Velocity (V ) was also measured on cubes of size 150 mm

150 mm 150 mm using same mix alongside UPT tests. The ultra-

sonic pulse velocities through the setting concrete are obtainedand plotted (Fig. 15). The plot clearly shows   V   increases with

hardening of concrete with time. It increases fairly uniformly from

1000 m/s to 3000 m/s in the transition phase. Similar to UPT, the

repeatability and accuracy of the UPV method is well established

by conducting the same on 3 h, 6 h, 12 h & 18 h cube specimens.

The results show similar trends as 24 h beam samples (Fig. 16).

Correlation between V  and R  is studied in Fig. 17. They have an

inverse relationship. A linear is developed between  V  and R:

V  ¼ ½ðV  f    V iÞ=ðRi  R f ÞðR  R f Þ ð3Þ

where V  f  is the final setting velocity of UPV (about 3000 m/s); R f  is

the peak–peak voltage ratio in the set concrete (0.3 in the present

case).

4.3. Comparison of NDT systems

It is evident from the above discussion that penetration test is

effective in estimating the initial setting time of concrete while

UPV is only applicable for final setting process. Both of them are

laboratory procedures and not amenable to field application. UPT,

on the other hand, is capable of picking up the initial setting of con-

crete through sudden change in the slope of  R. It also correlates

very well with UPV. Thus, it can give an estimate of in-situ setting

of concrete until it finally sets. Thus, it is effective in estimating

both initial and final setting times. Considering that UPT can be

carried out as the concrete is placed at site it can be very useful

in directly monitoring the concrete and benchmarking it against

acceptable standards. It should also be able to predict the strength

properties of concrete. Two important properties are compressivestrength and bond strength. In the next section, we observe the

correlation between the strength parameters and R.

4.4. Destructive testing 

To correlate the ultrasonic signals with in-situ strength of con-

crete, destructive tests of pullout and compressive strengths were

conducted atthe end of3 h,6 h, 12h, 18h and 24h durations.Min-

imum three samples were tested for each case. The results of these

tests are presented in Table 3. The variation in pull out strength is

presented in Fig. 18a. It is seen that the pull out strength increases

fairly uniformly with time after six hours have elapsed after casting.

Before that time the pull out strength is negligible. It correlates well

with compressive strength (Fig. 18b). With increasing age of con-crete as concrete sets, both pull outand compressive strengths show

an increasing trend. Maximum increase in pull out strength as well

as compressive strength indicated by sharp slope in the plots is

observed in the solid phase when concrete has attained sufficient

solidification andtransition in phase fromsemi-solid to solid. Corre-

lation between ultrasonic voltages and destructive tests of pull out

and compressive strengths has also been attempted.

4.5. Calibration of ultrasonic voltages with destructive tests

Fig. 19showsa plot of compressive strength andpull outstrength

with ultrasonic transmitted pulse voltage ratios obtained with

0.1 MHz frequency.It is observed that as theconcrete setswith time,

transmitted pulse voltage drops dueto increasing attenuationof thesignal in the embedded waveguide as a result of more leakage of 

Fig. 15.  Variation of Ultrasonic Pulse Velocity (V ) with age of concrete.

Fig. 16.  Variation of  V   for different ages of concretes.

Fig. 17.  pk–pk voltage in UPT vs. UPV.

 Table 3

Destructive test results at different stages of pouring concrete.

Sample Pull-out strength (kN/m2) Compressive strength (kN/m2)

S24 167 10.6

S18 102 6

S12 75 3.98

S6 20 1.8

S3 Test could not be conducted 0.7

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ultrasonic energyinto hardeningconcrete.The drop in R withsetting

as concrete solidifies approximately follows a parabolic trend in the

transition zone when it changes fromRi to R f . (Fig. 9). With dropping

voltage of the transmitted signal as concrete sets, an increase in

compressive strength and pull out strengths is observed. The mea-

sured voltage of the transmitted pulse at an instant can be related

to its expected in-situ compressive strength and pull out strength

as shown in Fig. 19a and b. Correlation of the ultrasonic voltages

with compressive strength andpullout strength hasbeen attempted

in the form of algebraic equations. These should facilitate non-

destructive evaluation of solidifying concrete immediately after

pouring. Butthese relationships are based on initial results andthey

should be further refined with more tests.

4.5.1. Compressive strength

As the concrete solidifies, there is an increase in compressive

strength and fall in voltage amplitude. The in-situ compressive

strength at any instant   t  after pouring concrete in the mold (C t )

increases parabolically as concrete sets. It is analogous to parabolic

variation of  R  with age of concrete (Fig. 9). The boundary condi-

tions are:

At initial stage the compressive strength is zero; at   R = Ri = 1,

C  = 0.

At the final stage (24 h of after pouring) compressive strength of 

concrete is C 24.

i.e at R  = R f  0, C  = C 24.An intermediate point at R  = 0.5, C  = C 24/5.

Fitting a parabola between the three points the estimated com-

pressive strength at an instant is:

C t  ¼  C 24½1 2:2R  1:2R2 ð4Þ

4.5.2. Pull out strength

A similar relationship between pullout strength and  R   can be

developed from the boundary conditions.

At the initial stage the pullout strength is zero; At   R = Ri = 1,

P  = 0.At the final stage (24 h after pouring of concrete)   R = R f  0,

P  = P 24.

At an intermediate point,  R  = 0.5, C  = P 24/4.

The equation of the parabola equation passing through these

points is:

P t  ¼  P 24½1 2R þ R2 ð5Þ

The corresponding curves have been depicted in Fig. 19a and b.

5. Conclusions

Ultrasonic guided waves provide an effective continuous, real

time and in-situ monitoring technique for investigating the prop-erties of concrete immediately after pouring. Reinforcing bars

Fig. 18.  Variation in in-situ strengths with age of concrete.

Fig. 19.  Correlation of pk–pk voltage ratio (R) with in-situ strength.

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acting as an embedded wave guide utilizing specific low frequency

surface seeking modes successfully identifies progression of setting

and bond development characteristics of young concrete. By opti-

mal selection of a guided wave mode which is sensitive to con-

crete–rebar interface characteristics, the setting of fresh concrete

and its bond development with the surrounding concrete can be

characterized. It provides an efficient means of characterizing var-

ious properties of concrete at early age. The methodology estab-

lished by this study can combine the existing techniques of 

measuring initial setting properties through needle penetration

and final setting properties through ultrasonic pulse velocity. It is

established that the peak-to-peak voltage and compressive

strength of concrete has a parabolic relationship. The bond

strength between concrete and the reinforcement too has a para-

bolic relationship. An initial mapping between the in-situ com-

pressive and pull out strength of the concrete at different stages

of setting with the voltage ratios is attempted here. These should

facilitate non-destructive evaluation of solidifying concrete imme-

diately after pouring. However, the relationships presented here

are based on limited early results and they should be subjected

to scrutiny with more tests.

 Acknowledgements

The fund received from the University Grants Commission

(UGC), Government of India vide Grant No. 41-194/2012 is

gratefully acknowledged.

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