Investigation on pulse velocity changes in RCC with different cement content and different types of admixtures

The 7th
International Symposium on Roller Compacted Concrete (RCC) Dams
Investigation on pulse velocity changes in RCC with different cement
content and different types of admixtures
Shabani,N.1
, Araghian H.R.2
1, Msc. In Hydraulic Structures,Email:shabaninaser47@yahoo.com
2, Concrete & RCC dams designer & Specialist,Email:hra@hra.ir
Abstract: RCC dams are going to be extended in water resource projects, so the new methodologies are also
needed to evaluate this type of concrete. One of these methods is pulse velocity measurement for assessment
of the quality and evaluation of uniformity of RCC. In this research, pulse velocity through the RCC (as a
non-destructive test has been measured and also its changes have been detected. For this purpose 20 types of
Mix designs with the same aggregates but different cementitous contents(100kg,125kg,150kg,175kg&200kg)
and three types of chemical admixtures (retarder, plasticizer and super plasticizers) have been made in the
laboratory and water cured up to 90 days. After measurement of pulse velocity in cylindrical 15X30 samples,
other mechanical tests such as the compressive strength, Indirect tensile strength, Static & dynamic elasticity
modulus and permeability of the samples have been tested and the results were evaluated.
Key words: Pulse Velocity measurement,Roller Compacted Concrete,admixtures.
1 Introduction
Non-destructive testing is one of the measures required for technical inspection and assessment of
the structures. As the name implies, non-destructive testing methods without any damaging to the
structure assess the situation. In general, by using non-destructive tests on concrete structures
important characteristics such as uniformity ,homogeneity , depth of surface cracks & modulus of
elasticity Will be evaluated.
One of the non-destructive test methods is ultrasound. In this way, by measuring the pulse rate in
various parts of the concrete structure valuable information could be found. Considering the
similarity of Roller compacted concrete with conventional concrete in hardened state & also
excessive use in water resources projects as well as the other advantages mentioned new methods
such as the use of ultrasound speed to assess this type of concrete is also taken into consideration.
With regard to specific circumstances and dry state and zero slump of Roller compacted concrete,
in this research it is tried to examine the quality and uniformity of this type of concrete by using
pulse rate method In this study 20 different concrete mixture with fixed amount aggregates and
different cement content of 100, 125, 150, 175 and 200 kg per cubic meter and three types of
chemical admixtures such as plasticizer, superplasticizer, retarder and also without admixtures
have been made and cured in the laboratory up to 90 days. After definition of pulse velocity in
cylindrical samples (300X150mm),compressive strength, splitting tensile strength (Brazilian),
elasticity modulus (static and dynamic) and permeability have been determined.

The 7th
2 Theory of research
Ultrasonic pulse velocity method is based on measuring the speed of pulses which is sent by a
transmitter to a receiver on the other side of the. The speed of sound in is related to concrete
modulus of elasticity and density, which are influenced by numerous factors, including the type of
cement, concrete age, water-cement ratio, the ratio of aggregate used in concrete and concrete
curing conditions [3]. So Pulse rate can be set for determination of uniformity of concrete,
estimated concrete strength, modulus of elasticity, measured properties of concrete with the
passage of time, the degree of hydration of cement, concrete durability and can be used to estimate
the depth of the cracks[ 5.4]. This method has been developed in recent years and one of its
advantages is that the equipment is portable.
Mechanical pulses concrete wave that includes three types of waves including longitudinal waves
(compression), shear wave (transverse) and surface wave. Longitudinal waves are the fastest waves
are suitable for testing. The relationship between velocity, modulus of elasticity and density of
concrete is as follows:
Eq.1))𝑉 = √
(1 − 𝜇)𝐸 𝑑
𝜌(1 + 𝜇)(1 − 2𝜇)
Which:
V=longitudinal wave speed,Ed=dynamic elasticity modulus, 𝜌 =density and 𝜇=concrete poisson’s
ratio.[6]
Since the range of Poisson's ratio in concrete (between 0.15 to 0.25) and variety of density for
different concrete types, can be said that the pulse velocity (V) and dynamic modulus of elasticity
(Ed) are related together and associated with changes in modulus of elasticity pulse rate also
changes.
3. Materials & Methods
Method of the research is based on Laboratory tests and the materials used to make the roller
compacted concrete mixtures was aggregates, cementitious material, water and the admixtures.
Aggregates consisted of three categories such 0-5 mm crushed sand, rounded 0-20 mm and crushed
20-50 mm sources on which have been provided from CHAMSHIR dam borrow areas. Quality
control tests such as determination of specific gravity (bulk, real saturated surface
dry) ,determination of water absorption have been conducted on the aggregates. The ratio of
aggregates in the mixtures was 30% for 0-5 mm sand,45% for 0-20mm,25% for 20-50mm. Mixed
aggregate size distribution curve is shown in Figure 1.
Cement used was type 2 and physical and chemical tests have been conducted on cement showed
its compliance with ASTM C150. Water for RCC mixtures were obtained from drinking water
supply. Determination of density and dry residue tests were conducted on admixtures used in this
research. The results of the physical and chemical tests, were presented respectively in Tables 1 and
2 respectively. The results of admixtures tests are shown in Table 3.

The 7th
Figure 1. Combined particle grading (Dash red line shows total grading of mixes)
Table 1. Physical test results of cement
Compressive
Strength
(28 days)
Setting time
(Vicat)BlaineDensity
Autoclave
Expantion
Normal
consistency
Test InitialFinal
psiminmincm2
/grgr/cm3%%
320023017031003.17+0.0821.2Result
Table 2. Chemical test results of cement
C4AFC3AC2SC3SSO3K2ONa2OMgOCaO
Fe2O
3
Al2O
3
SiO2Combined
14.36.0928.9042.902.120.610.271.7562.304.705.3021.36%
Table 3. Test results of chemical admixture
RetarderPlasticizerSuper-plasticizerAdmixture
Dry
Remaining
%
Density
gr/cm3
Dry
Remaining
%
Density
gr/cm3
Dry
Remaining
%
Density
gr/cm3
Test
27.91.1229.81.1449.051.20Result
Five different amount of cement have been used for making the RCC mixtures including
100,125,150,175& 200 kg. Three different type of admixtures including plasitciser,super plasticiser
and retarder were also used in the samples. Total number of RCC mixtures was 20 different mixes
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100
passing%
mm
Limit
Curve

The 7th
including control mixtures. Mixtures components used in this research for one cubic meter is
shown in Table 4.
Table 4. Mix designs with different cement content and different admixtures
RCC-200RCC-175RCC-150RCC-125RCC-100
ID
SplPlsRetTesSplPlsRetTesSplPlsRetTesSplPlsRetTesSplPlsRetTes
21502150215021502150
Agg
(kg)
200175150125100
C
(kg)
1131201271351041101181279310010811590971051138893.5100110
W
(kg)
0.570.600.640.680.590.630.670.730.620.670.720.770.720.780.840.900.880.941.001.10W/C
Tes = Testifier, Ret = Retarder, Pls = Plasticizer, Spl = Superplasticizer
After preparation of the final mixes, aggregates and other constituents to produce 0.1 cubic meters
of concrete was carefully weighted. Aggregates were poured first into the mixer and allowed to mix
with each other. Then cement was added to the mixed aggregate and re-mixing took place. Finally,
the water admixture were added to the mixture and mixing continued for 3 to 4 minute. In order to
determine the water-cement ratio (w/c) for each mix, based on Vebe time and with a trial and error
tried to achieve the optimal water content for a optimum Vebe time of 10 to 14 seconds.
Specific gravity and vebe time of fresh concrete according to ASTM C 1170 by using a 12.5 kg
surcharge have been determined. To make a 300 × 150 mm cylindrical samples according to
standard ASTM C1176 a 9.1 kg surcharge and a vibrating table were used. The samples removed
from molds after 24 hours and were kept in curing pool up to 90 days. 90-day compressive strength
test samples according to ASTM C-39, Brazilian tensile strength according to ASTM C-496, the
modulus of elasticity according to ASTM C-469, permeability according to EN 12390-08 and pulse
velocity according to ASTM C-597 were performed. By using pulse velocity, poissons’ ratio and
density of each sample, dynamic modulus of elasticity was obtained by using Equation 1.
For determination of ultrasonic pulse velocity the device shown in Figure 2 is used. The apparatus
consists of a electrical pulses generator, amplifiers and electronic instrument for measuring the
pulse transit time between the transmitter and receiver. Usually to carry out tests on concrete
generators with a frequency between 25 and 100 kHz is used. High-frequency generators for short
distance transport of pulses or thin concrete sections and generators with low frequency pulse are
used for a relatively long path and thick concrete sections. But in general, in most cases, 50 to 60
kHz frequency generators are appropriate. In this study, the frequency is 54 kHz.

The 7th
3.500
3.700
3.900
4.100
4.300
4.500
4.700
10 15 20 25 30 35 40
PulseVelocity(km/s)
Compressive Strength (MPa)
Tes Ret Pls Spl
Figure 2. Pulse velocity apparatus used in this study
4. Analysis of laboratory results
Figure 3 (a) shows that by increasing the amount of cement and with a fixed amounts of other
components ultrasonic pulse velocity increased in all of the mixtures. The use of plasticizer
admixtures in comparison with retarders is more effective on the speed of ultrasonic pulses through
the roller compacted concrete. Super-plasticizer admixtures is more effective on pulse velocity in
concrete compare with two other type of admixtures in fixed cementitious materials. The reason
can be assumed that better dispersion of the cement particles and also decreasing the water cement
ratio produces a denser concrete and the pulse velocity is increased.
It is interesting that pulse velocity in mixtures with plasticizers is slightly more than retarded
mixtures with fixed cementitious materials. All of the mixtures with admixtures have a higher pulse
velocity than control mixture. This is considered due to the lower water cement ratio of mixes with
admixtures and better dispersion of cement particles.In lower compressive strengths, between 10 to
20Mpa retarders are the best admixtures for the studied mixtures. Between 17-25 Mpa compressive
strengths, plasticizers and super-plasticizers have equal effect on pulse velocity. But beyond the 25
Mpa (150 kg cementitious materials) compressive strength, super-plasticizers are the most effective
in Roller compacted concrete mix designs. This is probably due to the higher cement in the RCC.
(a) (b)
Figure 3. Pulse velocity changes with different cement content and different types of
admixtures (a), Pulse velocity versus compressive strength relationship (b)
3.500
3.700
3.900
4.100
4.300
4.500
4.700
RCC-100 RCC-125 RCC-150 RCC-175 RCC-200
PulseVelocity(km/s)
Tes Ret Pls Spl

The 7th
3.500
3.700
3.900
4.100
4.300
4.500
4.700
10000 15000 20000 25000 30000 35000PulseVelocity(km/s)
Elasticity Modulus (MPa)
Tes Ret Pls Spl
3.600
3.800
4.000
4.200
4.400
4.600
4.800
0.01 0.015 0.02 0.025 0.03 0.035 0.04
PulseVelocity(km/s)
Porosity
Tes Ret Pls Spl
Longitudinal wave velocity depends on the elastic properties of roller compacted concrete and it is
a function of the modulus of elasticity and consequently it is associated with compressive strength.
Therefore, as in Figure. 3 (b), 4 (a) and 4(b) observed, By increasing the compressive strength,
tensile strength and modulus of elasticity ultrasound pulse velocity is also increases.
(a) (b)
Figure 4. Pulse velocity versus indirect tensile strength (a), Pulse velocity versus static
elasticity modulus (b)
Figure 5 shows the relationship between ultrasonic pulse velocity and permeability and also
porosity. Increasing the velocity of pulse represents the low porosity and consequently the low
permeability of roller compacted concrete. Using the plasticizers and super-plasticizers increases
the density of RCC and then increases the pulse velocity in roller compacted concrete. Retarders
also causes the cement particles hydrated slower and the crystals be smaller, more stable and closer
together, that this reduces the porosity, permeability and thus increase the pulse velocity in roller
compacted concrete.
(a) (b)
Figure 5.Pulse velocity versus permeability (a), Pulse velocity versus porosity (b)
3.500
3.700
3.900
4.100
4.300
4.500
4.700
1 2 3 4 5
PulseVelocity(km/s)
Indirect Tensile Strength (MPa)
Tes Ret Pls Spl
3.600
3.800
4.000
4.200
4.400
4.600
4.800
0 5E-12 1E-11 1.5E-11 2E-11 2.5E-11
PulseVelocity(km/s)
Permeability (m/s)
Tes Ret Pls Spl

The 7th
5 Dynamic Elasticity Modulus Calculation
Dynamic modulus of elasticity of concrete is related to a strain of very small spot. Ratio of
dynamic elasticity modulus (Ed) to static elasticity modulus is not fixed. BS 8110: part2 for normal
concrete represents the relationship between these fore-mentioned elasticity modulus as follow:
𝐸𝑐 = 1.25𝐸 𝑑 − 19 Eq.2
For Stress analysis in the dams, which may be affected by the earthquake load, dynamic modulus of
elasticity should be used which may be determined by equation 2 or by ultrasonic test.
In this study, dynamic modulus of elasticity of cylindrical roller compacted concrete samples which
have been made in the laboratory, was tested by using ultrasonic pulse velocity test method
according to ASTM C-597 standard. After Non-destructive tests, static modulus of elasticity test
method according to ASTM C- 469 also carried out and the results are compared in Table 5. For the
calculation of dynamic elasticity, Poisson's ratio of 0.2 is considered.
Table5. compressive strength, static & dynamic elasticity modulus
fc
(Mpa)
Ec
(Mpa)
Ed
(Mpa)
No
fc
(Mpa)
Ec
(Mpa)
Ed
(Mpa)
No
23.719763392261110.714310307611
25.919979406901211.713340340572
20.923818361151316.913447347373
23.123815395891417.913525354234
28.424768400461513.116680330515
30.724890434641614.715178356826
27.427568373081719.816325370797
28.128580404141821.316563378778
34.530282409681917.321068348229
35.830628447592020.4200633832410
According to the Table 5 values in the range of 1.35 to 2.62 for ratio of dynamic to static elasticity
is achieved. It is evident that with increasing the compressive strength of samples, the ratio of
dynamic to static elasticity modulus is decreased.
6 Conclusion
• By increasing the amount of cement and fixed amounts of other components, the pulse velocity in
roller compacted concrete increases in all of the cement content.
• Use of a plasticizer admixtures compared to retarder is more effective on pulse velocity through
roller compacted concrete and super-plasticizers have more effect compared with other plasticizers
and retarders.
• The use of plasticizer and super-plasticizer admixtures in the roller compacted concrete mix
design makes better the compaction and the use of retarders also causes the cement gently hydrate
and crystals smaller, more stable and closer together so that the porosity and permeability of RCC
reduces and pulse velocity increases.

The 7th
• The ratio of Dynamic Elasticity Modulus to Static Elasticity Modulus will be decreased by
increasing the cement content and thus by increasing the compressive strength.
• Ultrasonic method can be used as a suitable test for checking the roller compacted properties such
as density (& compaction), tensile strength, elastcity modulus and compressive strength.
References
[1] ACI (2011) “Roller-Compacted Mass Concrete”. Reported by ACI Committee 207, ACI
207.5R-11.
[2] U.S.Army Corps of Engineers, engineering and design manual, EM 1110-2-2006, 15 Januray
2000.
[3] Bungey. J. H., Millard. S. G., (1996), “Testing Of concrete in structures” Third Ed. Blackie
Academic & Professional, an imprint of Chapman & Hall.
[4] Krautkramer J., Krautkramer M., "Ultrasonic testing of materials",Berlin: Springer; 1990.
[5] Blitz J., Simpson G., "Ultrasonic methods of non-destructive testing",London, Chapman &
Hall; 1996.
[6] ASTM C597: Standard Test Method for Pulse Velocity through Concrete (2009).
[7] K.B. Sanish , Manu SANTHANAM, " Characterization of Strength Development of oncrete
Using Ultrasonic Method", 18th World Conference on Non-destructive Testing, 16-20 April
2012, Durban, South Africa.

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