EXPERIMENTAL STUDY OF EFFECT OF SODIUM SILICATE (NA 2 SIO 3 ) ON PROPERTIES OF CONCRETE

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http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=6&IType=12 ISSN Print: 0976-6308 and ISSN Online: 0976-6316

EXPERIMENTAL STUDY OF EFFECT OF

SODIUM SILICATE (NA

₂

SIO

₃

) ON

PROPERTIES OF CONCRETE

Ifrah Habib Lone, Abdul Muneeb, Javid Ahmad, Syed Mohammad Jasim,

Mintazir Ali, Mushtaq Ahmad Khan and Amir Hussain Malik

Department of Civil Engineering, University of Kashmir, India

ABSTRACT

This paper aims to investigate the effect of use of sodium silicate in cold

weather concreting. In order to illustrate such effect, a series of laboratory

tests were conducted. Workability tests, compressive strength tests, flexural

tests and split tensile strength tests were carried out on concrete specimens

having different percentage of sodium silicate and the results thus obtained

were compared with those of normal concrete. The results indicated that the

Sodium silicate does not contribute to an increase in strength of concrete,

rather it has reverse effects .However it does increase Compaction Factor,

thereby enhancing workability of concrete.

Key words: Sodium Silicate, Workability, Compressive Strength, Flexural

Strength and Split Tensile Strength.

Cite this Article: Ifrah Habib Lone, Abdul Muneeb, Javid Ahmad, Syed

Mohammad Jasim, Mintazir Ali, Mushtaq Ahmad Khan and Amir Hussain

Malik, Experimental Study of Effect of Sodium Silicate (Na2sio3) on

Properties of Concrete. International Journal of Civil Engineering and

Technology, 6(12), 2015, pp. 39-47.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=6&IType=12

1. INTRODUCTION

IS 7861 part II defines Cold Weather Concreting as Any operation of concreting done

at about 5°C atmospheric temperature or below.

ACI 306 “Cold Weather Concreting” defines cold weather concreting as a period

when for more than three (3) consecutive days, the following conditions exist:

 The average daily air temperature is less than 5°C (40°F) and,

 The air temperature is not greater than 10°C (50°F) for more than one-half of any 24 hour

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certain regions experience sub-zero temperatures in winter. Concrete structures in

such regions undergo cycles of freezing and thawing and their durability is affected

due to frost action. Fresh concrete contains considerable quantity of fresh water which

gets converted into ice lenses at freezing temperature. The ice formation in fresh

concrete results in about 9% rise in volume and causes permanent damage to concrete

and structural integrity cannot be recovered even if the concrete is made to harden

later at high temperature. Even during hardening the concrete should be protected

from extremely low temperature hence while concreting in cold weather ensure that

the temperature of fresh concrete is maintained above 0 °C and temperature during

first six hours of casting should not be less than 5 °C.

Stopping the process of concreting in winter is uneconomical due to long

downtimes of equipment and workers. It is better to bear additional costs and trying to

minimize them as much as possible. Thus, in winters, especially in Kashmir where the

temperatures are below zero degree in winters some admixtures need to be added to

nullify the effects of cold temperature on the strength of concrete. Considering the

availability and cost of the admixture, Sodium silicate is used as an admixture in

Kashmir in winters.

2. MATERIALS USED

Cement

Ordinary Portland Cement (OPC) 43 Grade (Safico cement) confining to IS: 4031[4]

has been used

for this Work. The properties of the used cement are shown;

Aggregates

Fine aggregates used throughout the work comprised of clean river sand with

maximum size of 4.75mm conforming to zone III as per IS:383-1970 [5] Coarse

aggregates used consisted of machine crushed stone angular in shape passing through

20mm I S sieve and retained on 4.75mm I S sieve .

Sodium silicate (Na

2

SiO

3

):

Color- Lemon-Orange

Appearance-Clear bright Liquid

Relative Density (g/ml)-2.4 g/ml

3. EXPERIMENTAL PROGRAM

Mix Used: Nominal mix M20 (1:1.5: 3) with water to cement ratio of 0.5.

In total four castings were done at the sodium silicate percentage of 1, 1.4, 1.8 and 2.2

First Casting Average Temp: 1.2

0

C

Percentage of sodium silicate by weight of cement = 1 %

Fineness % Standard Consistency (%) Initial Setting Time Final Setting Time Soundness (mm) Compressive strength(N/mm2) 2.28 26 1 hr. 16 min 6 hrs. 15 min 2 34.28

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Compressive Strength (σ

c

)

Cube size(mm)

7 Days Strength 28 Days Strength

Strength (N/mm2) Average Strength

(N/mm2) Strength (N/mm 2 ) Average Strength (N/mm2) P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 150 12.89 12.22 13.11 12.33 24 22.44 23.11 21.28 150 13.33 12.44 22.22 21.33

Split Tensile Strength (σ

t

) and Flexural Strength (σ

b

)

Type of concrete (σt) (N/mm 2

) (σb) (N/mm 2

) Slump Compaction factor

PCC 2.1 2.2 12 mm 0.71

CC with sodium silicate 1.96 2 15 mm 0.80

Second Casting

Average Temp: 1.6

0

C

Percentage of sodium silicate by weight of cement = 1.4 %

Compressive Strength (σ

c

)

(N/mm2) Strength (N/mm 2 ) Average Strength (N/mm2) P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 150 9.77 8.44 11.10 8.66 21.33 18.44 21.99 18.06 150 12.44 8.88 22.66 17.68

Split Tensile Strength (σ

t

) and Flexural Strength (σ

b

)

Type of concrete Split tensile strength (N/mm2) Flexural strength (N/mm2) Slump Compaction factor PCC 1.68 2.2 11.5 mm 0.73 CC with sodium silicate 1.26 1.8 20 mm 0.84

Third Casting Average Temp: 1.2

0

C

Percentage of sodium silicate by weight of cement = 1.8 %

Compressive Strength (σ

c

)

(N/mm2) Strength (N/mm 2 ) Average Strength (N/mm2) P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 150 11.11 6.66 21.77 16.88

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Split Tensile Strength (σ

t

) and Flexural Strength (σ

b

)

Type of concrete

σ

t (N/mm2)

σ

b (N/mm2) Slump Compaction factor

PCC 1.4 2.2 13 mm 0.75

CC with sodium silicate 0.56 1.6 20 mm 0.85

Fourth Casting

Average Temp:-1

0

C

Percentage of sodium silicate by weight of cement = 2.2 %

Compressive Strength (σ

c

)

(N/mm2) Strength (N/mm 2 ) Average Strength (N/mm2) P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 P.C.C C.C with Na2SiO3 150 10.22 8.22 9.99 7.66 22.22 20.00 22.17 20.88 150 9.77 7.11 22.13 21.77

Split Tensile Strength (σ

t

) and Flexural Strength (σ

b

)

Type of concrete

σ

t (N/mm2)

σ

b (N/mm2) Slump Compaction factor

PCC 1.4 2.8 12.5 mm 0.72

CC with sodium silicate 0.88 2.2 22 mm 0.87

4. DISCUSSION

In order to study the rate of variation of strength with respect to the Sodium Silicate

percentage, a comparative study of the test results achieved at different Sodium

Silicate percentage is performed.

Following Variations are studied

Variation of decrease in 7 day strength with Sodium Silicate %

Variation of decrease in 28 day strength with Sodium Silicate %

Variation of split and flexural tensile strength with Sodium Silicate %

Comparison of Avg. ↑ in 7 and 28 day strength for 150mm cube

Variation of compaction factor on adding Sodium Silicate.

7 Days Compressive Strength (σ

c

)

Cube

Plain (casting I) Plain (casting II) Plain (casting III) Plain (casting IV) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) 150 12.89 13.11 9.77 11.10 11.11 11.99 10.22 9.99 150 13.33 12.44 12.88 9.77

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Cube Admixture 1% (casting I) Admixture 1.4% (casting II) Admixture 1.8% (casting III) Admixture 2.2% (casting IV) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) 150 12.22 12.33 8.44 8.66 6.66 6.55 8.22 7.66 150 12.44 8.88 6.44 7.11

28 Days Compressive Strength (σ

c

)

Cube

Plain (casting I) Plain (casting II) Plain (casting III) Plain (casting IV) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) 150 24.00 23.11 21.33 21.99 20.88 22.00 22.23 22.19 150 22.22 22.66 22.31 22.13 Cube Admixture 1% (casting I) Admixture 1.4% (casting II) Admixture 1.8% (casting III) Admixture 2.2% (casting IV) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) Strength (N/mm2) Avg. Strength (N/mm2) 150 22.44 21.88 18.44 18.06 16.88 17.79 20.00 20.88 150 21.33 17.68 17.77 21.77

Average decrease in 7 days and 28days strength (%age)

Percentage of sodium silicate Average % decrease in 7

days strength Average %decrease in 28 days strength 1 -5.9 -5.32 1.4 -21.98 -17.87 1.8 -45.37 -19.13 2.2 -23.32 -5.9

Average decrease in Split tensile strength (σ

t

) and Flexural strength (σ

b

)

Percentage of sodium silicate

Average percentage decrease in Split

tensile strength

Average percentage decrease in Flexural strength

1 -14 -9.09

1.4 -25 -18.18

1.8 -60 -27.27

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GRAPH 1

GRAPH 2

GRAPH 3

-50 -40 -30 -20 -10 0 0 0.5 1 1.5 2 2.5 % ag e d e cr e ase in st re n gt h

%age of admixture

Average decrease in 7 day compressive strength

-70 -50 -30 -10 0 0.5 1 1.5 2 2.5

%

ag

e

d

e

cr

e

ase

in

st

re

n

gth

%age of admixture

Average decrease in split tensile strength

-35 -30 -25 -20 -15 -10 -5 0 0 0.5 1 1.5 2 2.5 % ag e d e cr e ase in st re n gt h %age of admixture

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GRAPH 4

The results graphs and tables represent the comparative study:

From the study of GA it is clear that the by adding Sodium both 7 and 28 day

strength for 150 mm cube decreases and reach their minimum at the sodium silicate

percentage of 1.25%,the decrease in 7day strength is 214% more than increase in 28

day strength.

0.79 0.8 0.81 0.82 0.83 0.84 0.85 0.86 0.87 0.88 0 0.5 1 1.5 2 2.5

%

ag

e

in

cr

e

ase

in

co

m

p

acti

o

n

fa

cto

r

%age of admixture

Variation of CF with %age of sodium silicate

-50 -40 -30 -20 -10 0 0 0.5 1 1.5 2 2.5

%

ag

e

d

e

cr

e

ase

in

st

re

n

gth

%age of admixture

GA:Comaprison between Average decrease

in 7 and 28 day compressive strength

7-day strength 28-day strength

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G6 shows that the compaction factor always increases when compared with the plain

concrete, thus workability increases by the addition of sodium silicate.

5. CONCLUSION

After analyzing the test results following important conclusions are drawn:

 Sodium silicate does not contribute to an increase in strength of concrete, rather it has reverse effects. The results indicated that while a hastened stiffening of the paste resulted from the admixture of sodium silicate no gain in the 1-day strength was obtained and the loss in strength at later ages was so great that it is only under exceptional conditions that the use of sodium silicate is advisable.

 Both 7 and 28 day strength for 150 mm cube decreases and reach their minimum at the sodium silicate percentage of 1.25%, the decrease in 7day strength is 214% more than increase in 28 day strength.

 However it does increase Compaction Factor, thereby enhancing workability of concrete

REFERENCES

[1] M.S. Shetty, Concrete Technology, Chapters 1- 8,page nos. 1 – 330, [2] IS 9103: 1999, Admixtures: definition, Page nos (23, 24).

[3] IS 456 : 2000, strength of concrete: tests, compressive strength .pages (2-7) [4] Abbas S. Al-Ameeri, K.A.Al- Hussain and M.S Essa, “Constructing a

Mathematical Models to Predict Compressive Strength of Concrete from Non-Destructive Testing”, International Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 4, 2013, pp. 1 - 20, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

[5] Alaa Abdul Kareem Ahmad, “The Effect of Gypsum Compensative on Mortar Compressive Strength”, International Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 3, 2013, pp. 168 - 175, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

[6] P.J.Patel, Mukesh A. Patel and Dr. H.S. Patel, “Effect of Coarse Aggregate Characteristics on Strength Properties of High Performance Concrete using Mineral and Chemical Admixtures”, International Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 2, 2013, pp. 89 - 95, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316. 0 0.2 0.4 0.6 0.8 1

1st casting 2nd casting 3rd casting 4th casting

GB:Variation of CF with plain concrete and

concrete with admixture

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[7] Dr. Shanthappa B. C, Dr. Prahallada. M. C. and Dr. Prakash. K. B., “Effect of Addition of Combination of Admixtures on the Properties of Self Compacting Concrete Subjected to Alternate Wetting and Drying”, International Journal of Civil Engineering & Technology (IJCIET), Volume 2, Issue 1, 2011, pp. 17 - 24, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

[8] M. VijayaSekhar Reddy, Dr .I.V. Ramana Reddy and N. Krishna Murthy, “Experimental Evaluation of the Durability Properties of High Performance Concrete using Admixtures”, International Journal of Advanced Research in Engineering & Technology (IJARET), Volume 4, Issue 1, 2013, pp. 96 - 104, ISSN Print: 0976-6480, ISSN Online: 0976-6499.

[9] Vinod P, Lalumangal and Jeenu G, “Durability Studies on High Strength High Performance Concrete”, International Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 1, 2013, pp. 16 - 25, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

[10] Ali S. Faris, Riadh Al-Mahaidi and Awad Jadooe, Implementation of Magnetized Water To Improve The Properties of Concrete, International Journal of Civil Engineering & Technology (IJCIET), Volume 5, Issue 10, 2014, pp. 43-57, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316