UNITEN ICCBT 08 Estimation of Static Elastic Modulus of HSC Using UPV Method

7/27/2019 UNITEN ICCBT 08 Estimation of Static Elastic Modulus of HSC Using UPV Method

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ICCBT 2008 - C - (22) - pp245-254

ICCBT2008

Estimation of Static Elastic Modulus of HSC Using UPV method

S. R. M. Khan*, Universiti Tenaga Nasional,MALAYSIA

K. N. Mustafa, Universiti Tenaga Nasional,MALAYSIA

M. S. Jaafar, Universiti Putra Malaysia,MALAYSIA

J. Noorzaei, Universiti Putra Malaysia,MALAYSIA

M. R. A. Kadir, Universiti Putra Malaysia,MALAYSIAW. A. M. Thanoon, Universiti Putra Malaysia,MALAYSIA

ABSTRACT

Static elastic modulus assessment of in-situ concrete using non-destructive technique is very

important for building or structural inspector. This paper presents a research finding that

establish a regression model between Ultrasonic Pulse Velocity (UPV) using direct method

(Vd) and actual static elastic modulus (Ec) of high strength concrete (HSC). In this study, a

total of 108 standard cylinder samples were made from six different mix proportions. Themixes were grouped in two series that consist of nominal maximum aggregate sizes of 10mm

(A10) and 19mm (A19). Silica fume were used as mineral admixtures at 5 percent, 10 percent

and 15 percent of cement in both series. UPV tests were conducted for each of the specimens,

followed by static elastic modulus tests. The tests were carried out for concrete at the ages of

28 and 56 days. The destructive test results understood as the actual value of static elastic

modulus of the HSC and the UPV test results were used as static elastic modulus estimation.

Concrete static elastic modulus correlations with UPV in each series of mixes have

established. These correlations are presented in the form of regression models that imply

maximum error of 4% for model of concrete series A10 and 7% for model of concrete series

A19. These models have overall correlation coefficients (r) above 0.85 for all the mixes. There

are no standard relationships for static elastic modulus that had been established for highstrength concrete with UPV parameters. The proposed relationship can be used for estimation

of static elastic modulus of HSC that is normally required in building or structural integrity

assessment.

Keywords: High strength concrete, Static elastic modulus, Ultrasonic pulse velocity method,

Aggregate size, Silica fume.

*Correspondence Author: Dr. Shibli R.M Khan, Universiti Tenaga Nasional, Malaysia. Tel: +60389212020,

Fax: +60389212116. E-mail: [email protected]
http://www.uniten.edu.my/newhome/content_list.asp?contentid=4017


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ICCBT 2008 - C - (22) - pp245-254 247

2. EXPERIMENTAL WORKMaterial and properties

Ordinary Portland cement (OPC) (BS 12, 1996) and densified silica fume (SF) in powder-form was used as cementitious material. Physical properties and chemical composition of the

cementitious materials are given in table 1. The coarse aggregate (CA) was crushed Sandstone

with 10mm (max) and 19mm (max) nominal size and was sourced from Hulu Langgat. The

fine aggregate (FA) was medium-graded (BS 882, 1992) siliceous sand and was sourced from

Puchong. A naphthalene sulphonated polymer-based superplasticizer (SP) (Axel NN 401)

admixture (BS 5075: part 3, 1985) with specific gravity of 1.11 was used. Water for mixing

and curing of concrete was taken directly from a tap supply at a temperature of approximately

26C.

Table 1: Physical properties and chemical composition of OPC and SF (% by weight)

Constituents OPC SF

SiO2 21.03 92

Al2O3 4.73 0.2

Fe2O3 2.93 0.1

CaO 63.63 0.1

MgO 2.67 0.2

Na2O 0.30 0.1

K2O 0.65 0.3

SO3 3.00 0.1

LOI 0.97 8.0Particle size 10- 50 0.1- 0.5

Bulk Density 3050kg/m3 640kg/m3

Six concrete mixtures were proportioned for this study, which was after using trial mix with

the targeted strength at 28 days of 60 MPa, 80 MPa and 100 MPa. The mixtures were divided

into series A10 and A19, which means mixture having maximum nominal coarse aggregate size

10mm and 19mm respectively. The mineral admixtures (SF) were used to add 5%, 10% and

15% of the mass of cement with respect to ascending order of concrete grade. The SP quantity

was adjusted with respect to the absorbed moisture in the sand (FA) and aggregate (CA)

during the mix. Mixture proportions are summarized in Table 2.Mixing and curing

Concrete mixing was accomplished in a 0.15-m3 capacity horizontal rotary drum mixer. The

coarse aggregate and fine aggregates were mixed first, followed by the addition of

cementicious material. Materials were mixed dry for a period of 3 minutes approximately.

Three quarters of the water was added while the CA and FA materials were being mixed,

finally the remaining water and followed by the SP. SP was adjusted to achieve required

workability. Wet mixing was continued for a total period of 6 minutes


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Estimation of Static Elastic Modulus of HSC using UPV method

ICCBT 2008 - C - (22) - pp245-254248

Table 2: High strength concrete mix proportions

Cylinder specimens were using 150 mm diameter and 300mm high steel moulds andcompacted in three uniform layers by means of vibrating tables. Eighteen cylinder specimens

were prepared for each mixture. After casting, specimens were covered with polythene sheet

to prevent moisture loss and were stored in the laboratory at ambient temperature 27C and

75% relative humidity. After 24 hours, specimens were demoulded and curing in a water tank,

under room temperature until the day of testing.

Static elastic modulus testing

In the present study standard cylinder specimens are cast and tested for the static elastic modulus

of HSC according to ASTM C 469 (1994) and the BS 1881: part 121(1983). It is also to be noted

that the universal testing machine, which was used, for the test displays directly stress and thestrain is measured from the device fixed on the cylinder as per ASTM C 469 (1994). The

specimens were test first by UPV before being tested for static elastic modulus. The static

elastic modulus test results are considered as the actual static elastic modulus value of the

concrete. Nine specimens were tested for UPV andstatic elastic modulus test in each maturity

ages.

Ultrasonic Pulse Velocity Test

There are three orientations to measure the transit time, which are direct, indirect and semi-

direct method. Direct transmission was used, since it is more reliable than the others two are.

The test procedures were conducted according to (BS 1881: Part 203, 1986) whereby fivepoints of each opposite plain faces were taken into consideration. The average value was

taken to represent the UPV value for that cylinder. Figure 1 depicts the grid points of two

opposite plain faces.

Cement

kg/m3

water

kg/m3

FA

kg/m3

CA

kg/m3

Silica

Fume

kg/m3

Super

Plasticizer

Liter/m3

Slump

(mm)

w/b(c+SF)

ratio Mix

500 170 590 1050 30 10 125 0.32 Mix1

550 140 645 1043 55 38 225 0.23 Mix2

Series

A10

550 140 635 1050 85 65 200 0.22 Mix3

500 165 580 1050 25 10 120 0.31 Mix4

500 140 638 1050 55 33 225 0.25 Mix5

Series

A19

550 135 630 1050 80 50 175 0.21 Mix6


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Figure 1: Standard cylinder (150mm dia. & 300mm high) depicting different position of

transducer of PUNDIT.

3. RESULTS AND DISCUSSION

The measurement of pulse velocity and corresponding static elastic modulus was taken at age

of 28 and 56 days. The results are then plotted for each series of mix (A10 and A19) and

articulated in Figure 2. The pulse velocity measurements were taken an average of five points

on each cylinder in the direct method. The UPV measurement has significant effect on the

aggregate sizes in the mix (Shibli et al, 2007; Price and Hynes, 1996). From Figure 2 it is

observed that correlation of UPV with static elastic modulus having similar phenomena with

strength correlations.

The coefficient of correlation for the regression model in series A10 was found to be 0.92 and

in series-A19, was 0.86 regardless of percentage of silica fumes added to the mix. The results

show that the maximum nominal aggregates sizes significantly affect the UPV test results.

Hence, the use of UPV in estimation of static elastic modulus in concrete cannot be used

satisfactorily without the information on the maximum aggregate sizes used in the mix.

It is always easy to estimate the maximum aggregate sizes for in-situ concrete; therefore, the

relationship established above may be applied to estimate static elastic modulus from UPV

tests. The regression models shown in Equations 3 and 4 are meant for concrete series A10 and

A19 respectively. The accuracy of these models are tested and articulated in Figures 3 and 4

for series A10 and A19 respectively. It was found that using these models the static elastic

modulus can estimate with maximum error of (+)3% upper bound and (-)4% lower bound for

HSC in series A10 (Eqn-3) and error of (+/-)7% for HSC in series A19 (Eqn-4).

77.3957.13 =dc

VE (3)

65.3505.15 = dc VE (4)

Transducers position

Cylinder plain faces

Gridline


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ICCBT 2008 - C - (22) - pp245-254250

Figure 2: Correlation of UPV and static elastic modulus of HSC

for mixes in series A10 and A19.

Figure 3: Estimated Static elastic modulus using Regression

model for series A10


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ICCBT 2008 - C - (22) - pp245-254 251

Figure 4: Estimated Static elastic modulus using Regression model for series A19

A confidence test was performed on the parameters of the developed models to investigate

whether a significant direct relationship exists between the static elastic modulus of HSC and

the UPV (Vd) for the concrete mix in series A10 and A19, the results of which are shown in

Table 3. Standard errors are estimates of uncertainties in the regression coefficients. The t-

statistic tests the null hypothesis that the regression coefficients is zero, that is, the

independent variable (Vd) does not contribute to estimating the dependent variable ( cE ) while

P value is the probability of falsely rejecting the null hypothesis. From the results, it is

concluded that the relationship is significant at 95% confidence limit thus, construed

reliability of the equation.

Table 3: Standard error of estimate andt-statistic for the regression coefficients

Slope, ( )or coefficients of

independent variables (Vd) n

Y-Intercept, ( )Variable

Parameter

..ES

t P ..ES t P

r Remarks

Series-A10 13.57 0.803 16.92 0.0000 -39.77 4.41 -9.02 0.0000 0.92 Linear

Series-A19 15.05 1.23 12.16 0.0000 -35.65 5.79 -6.15 0.0000 0.86 Linear


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4. LIMITATIONSAny prediction models bound to have flaws, and therefore, it is imperative that their

limitations be discussed and highlighted. Static elastic modulus prediction using UPV directmethod construed that sizes of the aggregate must be known before use any regression model

to predict the static elastic modulus. The maximum percentage of error for regression model

in series A10 implied 4 percent in lower bound. This model is also valid only for the UPV

values ranged from 5.1 km/sec to 5.7 km/sec with an equivalent predicted static elastic

modulus range from 31 to 38 GPa (Figure 2). On the contrary, the maximum percentage of

error for regression model in series A19 implied 7 percent. This model is also valid only for

the UPV values ranged from 4.3 km/sec to 4.9 km/sec with an equivalent predicted static

elastic modulus range from 31 to 38 GPa (Figure 2). This regression models can estimate

static elastic modulus with higher degree of accuracy for the concrete at age 28days or older.

However, for early age concrete the degree of accuracy has yet to be verified.

5. CONCLUSIONSThe examined results discussed in the preceding section have articulated that static elastic

modulus of high strength concrete can be estimated by the UPV, provided the aggregate sizes

of that concrete are known. It is also concluded that a linear model for concrete mix with

10mm and 19mm nominal aggregate size describe the relationship of static elastic modulus

UPV. The proposed linear regression models are 77.3957.13 = dc VE and

65.3505.15 = dc VE for HSC mix A10 and A19 respectively. These models are capable of

estimating static elastic modulus within the range 31 to 38 GPa with a maximum error of

7%. These models are also valid for the pulse velocity range from 5.1 to 5.7 km/sec and 5.3

to 4.9 km/sec respectively.

REFERENCES

[1]. Iravani Said, (1996). Mechanical Properties of High-Performance Concrete, ACI

Material Journal, American Concrete Institute, USA, Vol. 93, No. 5, pp. 416-426.

[2]. American Society for Testing and Materials (1991). Specification Test for fundamental

transverse, longitudinal and torsional frequencies of the concrete specimens (ASTMC215-91). Philadelphia, USA.

[3]. British Standard Institution (1990). Testing concrete: recommendations for

measurement of dynamic elastic modulus using velocity of ultrasonic pulses in concrete

(BS 1881: Part 209), London.

[4]. Almudaiheem J.A & Al-Sugair F.H, (1992, January). The water permeability of concrete

and its relationship with strength. Magazine of Concrete Research, Vol. 44, No. 158, pp

15-20.

[5]. Tomsett, H.N, (March 1980). The Partial use of Ultrasonic Pulse Velocity

Measurements in the Assessment of Concrete Quality. Magazine of Concrete Research,

Vol. 32, No. 110, pp. 7-15.


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ICCBT 2008 - C - (22) - pp245-254 253

[6]. British Standard Institution (1985). British Code for design of concrete structure

(BS8110: part-1). London, UK.

[7]. Lydon, F. D. and Balendran, R. V. (1986). Some observations on elastic properties of

plain concrete. Cement and Concrete Research, Vol. 16, No. 3, pp. 314-324.

[8]. Shibli R.M. Khan (2007), Development of regression models for predicting properties ofHigh Strength Concrete using Non-destructive tests PhD Thesis, pp 2.48 2.112.

[9]. BS 12: (1996), Specification for Portland cement, London. British Standard

Institution, UK.

[10]. BS 882: (1992), Specifications for aggregates from natural sources for concrete,

London, British Standard Institution, UK.

[11]. BS 5057: Part 3, (1985), Concrete Admixtures. Specifications for superplasticizing

admixtures, London, British Standard Institution, UK.

[12]. Leonard Runkiewicz and Maciej Runkiewicz, (2000), Application of the Ultrasonic

and Sclerometric Methods for the Assessment of the structures made of High-strength

concrete (HSC), Proceedings of 15th World Conference on Non-Destructive Testing,

Roma, pp. 10.[13]. American Society for Testing and Materials (1994). Specifications for static elastic

modulus of concrete (ASTM C469-94). Philadelphia, USA.

[14]. British Standard Institution (1983). Testing concrete: recommendations for

measurement of static elastic modulus in concrete (BS 1881: Part 121), London.

[15]. BS 1881: Part 203, (1986) Testing concrete - Recommendations for measurement of

Ultrasonic Pulses in concrete, British Standard Institution, UK.

[16]. Price, W.F., Hynes, J.P. (1996) In-situ strength testing of high strength concrete,

Magazine of Concrete Research, Vol. 48 No. 176, pp. 189-197.

[17]. Shibli R.M. Khan, J. Noorzaei, M.R.A Kadir, A.M.T Waleed and M.S. Jaafar (2007),

UPV method for strength detection of high performance concrete. Emerald - Structural

Survey, Vol. 25, No. 1, pp. 61-73.

UNITEN ICCBT 08 Estimation of Static Elastic Modulus of HSC Using UPV Method

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