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STUDY OF NON-DISTRUCTIVE TESTS ON

DIFFERENT TYPES OF MIX PROPORTIONS

M.VENKATA PAVAN 1 T.VINOD KUMAR1 SK.MABU SUBHANI1 B.RAVALI1

S.L.P.DURGA DEVI2

1. UG student, Civil Engineering, KHIT, Guntur, Andhra Pradesh, India.

2. Asst professor, Civil Engineering, KHIT, Guntur, Andhra Pradesh, India.

Abstract The need of construction is increasing day to day as

the population rate is increasing. Geopolymer

concrete is eco-friendly than ordinary concrete. This

paper presents the experimental investigation on

ordinary and geopolymer concrete using NDT tests

like Ultrasonic Pulse Velocity test (UPV) and

rebound hammer test. These tests are conducted on

the cube specimens of dimensions

150mmX150mmX150mm at different age’s i.e. 7, 14,

28 days. Proportions considered for concrete are

cement – fly ash – river sand (100-0-100 %, 60-40-

100%), cement- fly ash – robo sand (100-0-100%, 60-

40-100%). Whereas in geo polymer concrete fly ash-

metakaolin is taken in proportions of (100-0%, 60-

40% and 50-50%). Alkaline activators such as

sodium hydroxide and sodium silicate with molarity

12M are used in preparing geo-polymer concrete. The

main objective of this paper is to obtain the relation

between compressive strength and UPV values.

Keywords-

Flyash, Metakaolin, Robosand, Ultrasonic Pulse

Velocity, Rebound hammer.

I. INTRODUCTION

The non-destructive technique is a method widely

using for evaluating the property of materials,

component or system without causing any damage to

the structure. Any component of structure can be

tested a number of times using NDT to ensure the

safety, improve output, profitability and continued

integrity through the complete lifecycle.

In the recent past, there has been an

enormous increase in the usage of different types of

materials in concrete such as Fly ash. It becomes one

of the ingredients of concrete. Measurement of

strength of concrete through UPV was initiated in the

USA in the mid-1940 s and later adopted everywhere

as NDT on concrete. Ultrasonic Pulse Velocity

(UPV) is one of the non-destructive methods used for

testing of the quality of concrete, homogeneity and

compressive strength by the regression equation.

UPV methods basically consist of transmitting the

mechanically generated pulses (in the frequency

ranges of 20-150/s) through concrete with the help of

electro-acoustic transducers for measuring the

velocity of the longitudinal waves generated by the

applied pulse. UPV is correlated to much desirable

information pertaining to concrete, such as: – Elastic

modulus, strength, and uniformity of concrete –

Layer thickness, cracking, honeycombing and

deterioration of concrete.

Rebound hammer is one of the non-

destructive testing methods which are used to find out

the strength and elastic property of concrete or rock.

It is also known as SCHMIDT HAMMER. This

equipment was first introduced by ERNST

SCHMIDT, a Swiss engineer. This hammer is used to

measure the rebound number by using an arbitrary

scale ranging from 10-100 of the spring-loaded mass

by impacting the hammer at right angles to the

concrete or rock surface which should be flat and

smooth.

II. MATERIALS

A. CEMENT

Ordinary Portland Cement (OPC) 53 Grade was used

in this experimental study. Referring the IS 8112-

1989.The specific gravity of the cement is obtained as

3.10 by using density bottle. Chemical Properties of

cement are represented in Table 1.

Figure no 1: Cement

B. FLY ASH

Fly ash is one of the coal combustion product which

consists of fine particles collected from boilers with

flue gases. Fly ash used in this project is collected

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from the thermal power plant at Kondapalli, Krishna

district, Andhra Pradesh, India. Properties of Fly ash

were presented in Table 1.

Figure no 2: Fly ash

Table no 1: Chemical properties of Cement and Fly

ash

Composition of Cement and Fly ash

Component (%) Cement Fly ash

a) Chemical Analysis

Loss Ignition 1. 8 2.0

SiO2 20. 4 60.54

Fe2O3 3. 2 5.87

Al2O3 3. 9 26.20

CaO 63 1.91

MgO 2. 4 0.38

K2O + Na2O - 1.02

SO3 3 0.23

C. Fine aggregate:[4,5]

River Sand

River sand is a naturally obtained material from river

bank. It is widely used in normal construction works.

The fineness modulus of river sand is 2.75 and

conforming to zone III according to IS: 383-1970.

Figure no 3; River sand

Robo Sand

Robo Sand is a waste obtained from crushed

aggregates. The fineness modulus of robo sand is

3.62 and is conforming to Zone III as per IS: 383-

1970. It is also known as artificial sand.

Figure no 4: Robo sand

S. No. Property River sand Robo sand

1 Fineness

Modulus

2.65 3.56

2 Specific

Gravity

2.68 2.7

3 Silt Content 0.8%

D .Course aggregate:

Coarse aggregate is obtained from quarry site. The

aggregates of 20mm and 10 mm are used in this

experiment conforming to Zone III as per 10262-

2009. In this experiment, we are using 60% of 20mm

and 40% of 10mm aggregates.

Figure no 5: Course aggregate

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S. No Property Test Value

1 Specific Gravity 2.79

2 Water absorption 0.45%

4 Aggregate Impact

Value

21.70

5 Aggregate

crushing value

20.60

6 Combined

Flakiness &

Elongation Value

22.10

E. METAKAOLIN :

The dehydroxylated form of clay mineral

kaolinite is called metakaolin. It gives high strength

to the concrete the disordered kaolinite and ordered

kaolinites are converted into dehydroxylated at

temperatures of 530-5700C, 570-6300C . A light

Pinkish metakaolin is used in the present study. The

specific gravity of metakaolin is 2.45.

Figure no 6: Metakaolin

F.ALKALINE ACTIVATORS:

Sodium hydroxide and sodium silicate are the

chemicals used in the preparation of geopolymer

concrete.

Sodium hydroxide:

Generally, sodium hydroxide (NaOH) is available in

flakes and pellets. Sodium hydroxide flakes are used

in this experiment.

Sodium silicate:

Sodium silicate is also named as water glass or liquid

glass. Generally, these are available in the liquid state

(gel form).

III. METHODOLOGY

A. Solution preparation:

Sodium Hydroxide (NaOH) solution is prepared 24-

48 hours prior to the use in concrete. As it is in the

form of flakes, it is dissolved in water to prepare

sodium hydroxide solution. In this experiment 12M

(12 Molarity) is considered. So, for preparing a 12M

solution 480 grams of sodium hydroxide flakes are to

be dissolved in water to make one litre of sodium

hydroxide solution. When sodium hydroxide and

sodium silicate solutions are mixed, heat is liberated.

So, they must be mixed separately.

Molarity=moles of solute/litre of solution

12M=12 molarity

=2 x molecular weight

=12 x40

=480 gm.

B. Mix design:

The mix design for OPC concrete is done in

conventioonal method based on IS 456:2000. The w/c

ratio used for this mix is 0.35obtained by designing

M25 grade concrete. Mix design for geopolymer

concrete is done in trial and error method because

there are no confined codal specifications. The

density of concrete is taken as 2400 Kg/m3 for

calculation of quantities of materials.

According to 10262:2009, the total volume of coarse

and fine aggregates are 70% in the density of

concrete and remaining 30% of geopolymer binders

such as fly ash, metakaolin, and alkaline activators.

The mix proportions are represented in the table as

below.

Table no 4: Mix proportions for GPC

Table no 5: Mix proportions for OPC

Iv. TEST PROCEDURE

A. Mixing and Casting:

Mixing and casting of geopolymer concrete are

similar to conventional concrete. After mixing,

Mix No Mix Proportion

GPC 1 100%+0%MK

GPC 2 60%+40%MK

GPC 3 50%+50%MK

Mix No Mix Proportion

1 100%+0%FA+100%RS

2 60%+40%FA+100%RS

3 60%+40%FA+0%RS

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the concrete is cast in 150mm x150mm x 150mm

moulds. The casting is done by placing concrete

in three layers. Each layer is tampered 25 times

by using a tamping rod [7].

B. Curing:

Curing of geopolymer concrete is done by

ambient curing. For ordinary concrete, curing is

done by placing cubes into a water bath for

7days, 14 days and 28 days. After the curing

period is done the cubes are tested.

C. Testing:

i. Ultrasonic pulse velocity test procedure:[9]

The principle of ultrasonic pulse velocity test is

to measure the pulse of longitudinal vibrations

passing through the concrete. For the measuring

of travel time of wave through concrete. From

the experiments, the velocity depends on the

elastic property and geometry of the material.

The recommendations for the use of this method

are given BS-4408 part-5; ASTM C 597-71 and

BIS 13311 part -1-1992.

In this procedure, the direct method is used for

testing the specimens. For homogeneous

concrete, the compression wave velocity is given

by

V = √ (kEd/ρ) (1)

Where k = (1-γ) / [(1+γ) (1-2γ)] (2)

Ed= dynamic modulus of elasticity

ρ = dynamic poisons ratio

The velocity of an ultrasonic pulse is influenced by

properties such as elastic stiffness and mechanical

strength. The pulse velocity values may vary with the

variations in the state of concrete under test.

According to the obtained velocity values calibration

charts must be established to evaluate the

compressive strength and quality of concrete.

Figure no 7: UPV testing

Table no 6: velocity criterion for concrete quality

grading (As per IS 13311-part 1)

Pulse velocity

(Km/sec)

Quality of concrete

Above 4.5 Excellent (E)

3.5 – 4.5 Good (G)

3-3.5 Medium (M)

Below 3 Poor (P)

ii. Rebound hammer or Schmidt hammer test

procedure:[7]

The rebound hammer consists of a plunger which is

impacted against the concrete surface, the spring

which is present in the rebound extent with a

controlled mass depends upon the surface hardness of

concrete. Generally, different types of rebound

hammers are available based on different

applications. The impact energy may vary from 0.07-

3 kg-m. The number which is obtained from the

rebound index is calibrated to determine the

compressive strength.

The rebound test is conducted on the concrete

surface should be smooth, clean and dry. For some

rough surfaces present on the concrete, should be

rubbed with grinding wheel or stone. The point of

impacting the hammer should be 20mm far from the

edge and discontinuity shapes. The rebound hammer

should be kept perpendicular to the surface of the

concrete. On each surface, numbers of observations

are taken and the average of these observations gives

the strength of concrete.

The test procedure for determining rebound values

are as per ASTM C-805-85, BIS 13311 PART 2.

Figure no 8: Rebound testing

Table no: 7 Quality of concrete from rebound number

Rebound no. Quality of concrete

Above 40 Very good (VG)

30 -40 Good (G)

20-30 Fair (F)

Below 20 Poor (P)

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VI. RESULTS AND DISCUSSION:

1. For ultrasonic pulse velocity test:[6]

Table no 8: UPV values for OPC

Concrete

mix

UPV (Km/s)

7 days 14 days 28 days

MIX 1 4731 4913 5245

MIX 2 4913 5068 5372

MIX 3 3452 3816 4275

Table no 9: upv values for GPC

Concrete

mix

UPV (Km/s)

7 days 14 days 28 days

GPC 1 1534 2556 3884

GPC 2 2523 3596 4756

GPC 3 2573 3592 4165

Figure no 9: UPV values for OPC for different mix proportion

Figure no 10: UPV value for GPC for different proportion

Table no 10: Quality of ordinary and geopolymer concrete under the effect of ultrasonic pulse velocity with respect to age

Time

(days)

Quality of concrete

OPC GPC

mix-1

mix-2

mix-3

GPC-1

GPC-2

GPC-3

7 E G M P P P

14 E E G P G G

28 E E G G E E

E= excellent; G= good; M= medium; P= poor

For rebound hammer test:

Table no 11: rebound number for OPC

Concrete

mix

Rebound no.

7 days 14 days 28 days

MIX 1 33 25 26

MIX 2 36 28 29

MIX 3 38 31 30

Table no 11: rebound number for GPC

Concrete

mix

Rebound no.

7 days 14 days 28 days

MIX 1 28 27 26

MIX 2 29 28 28.5

MIX 3 31 31.5 31.25

Figure no 11: Rebound values for OPC

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Figure no 12: Rebound values for GPC

Table no 11: Quality of ordinary and geopolymer concrete under the effect of rebound hammer with respect to age

G= good; F= fair

Time

(days)

Type of concrete

OPC GPC

mix-1

mix-2

mix-3

GPC-1

GPC-2

GPC-3

7 G F F F F F

14 G F F F F F

28 G F G G G G

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Figure no 13: Relationship between compressive strength and ultrasonic pulse velocity test

There is no specific relation for UPV and compressive strength of concrete. From the above relations of compressive strength and ultrasonic pulse velocity values we have determined the following equations with respect to mix proportions[10]

1. y= 15.21e0.216x (mix 1) (3)

2. y= 0.014e1.411x (mix 2 ) (4)

3. y= 23.79e0.103x ( mix 3) (5)

4. y= 4.249e0.158x (GPC 1) (6)

5. y= 4.193e0.217x (GPC 2) (7)

6. y= 5.105e0.195x ( GPC 3) (8)

Where y= concrete compressive strength

x= velocity value of concrete

Figure no 14: equation obtained for OPC

Figure no 15: equation obtained for GPC

Conclusion

1. For this present experimental investigation we have determined an equation for the comparison of compressive strength and UPV values obtained.

2. The UPV and rebound values increase with the increases of curing period.

3. For mix 2 of OPC concrete the UPV values increases by 3.8% and 6.42% at 7 to 14 days and 14 to 28 days of curing respectively. For the same mix proportion the rebound value increases by 9.1% and 5.5% at 7-14 and 14-28 days of curing respectively.

4. For mix 2 of GPC the UPV values increases with 42.46% and 32.31% at 7-14 days and 14-28 days of curing respectively. For the same mix proportion the rebound increases by 3.57% and 6.89% at 7-14 and 14-28 days of curing respectively.

5. With reduction of fly ash content in GPC the passing time of longitudinal waves is lesser.

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Reference

1. K. Srinivasa Reddy (2016). Replacement of

natural sand with Robo or artificial sand in

specified concrete mix.

2. M. S. Shetty, concrete technology text book,

S. Chand and company limited.

3. IS 456: 2000. Recommended plain cement

concrete mix guidelines and reinforced

cement concrete BIS, New Delhi.

4. IS 10262: 1982. Recommended concrete mix

guidelines, BIS, New Delhi.

5. IS 383: 1979 recommended guideline for fine

aggregate, BIS, New Delhi

6. IS 13311(part 1):1992,non-destructive testing

of concrete -ultrasonic pulse velocity

(Reaffirmed 2004).

7. IS 13311(part 2):1992,non-destructive testing

of concrete-Rebound Hammer(Reaffirmed

2004).

8. R. AnuRadha(25 April 2011), Modified

guidelines for Geopolymer concrete mix

design using Indian standards ,Perth,

Australia.

9. S.krishna rao: Relationship between

Ultrasonic Pulse Velocity and Compressive

Strength for Roller Compacted Concrete

containing GGBS

10. Prof. Dr .Bayan s. Al-Numan(Aug 2015),

compressive strength formula for concrete

using ultrasonic pulse velocity, Erbil, Iraq.