estimation of desired properties of self curing concrete...

International Journal of Engineering Technology, Management and Applied Sciences

www.ijetmas.comApril 2017, Volume 5, Issue 4, ISSN 2349-4476

581 B. Ajitha, Ghantasala Nirupama

Estimation of Desired Properties of Self Curing Concrete using

Admixture

B. Ajitha*, Ghantasala Nirupama

Department of Civil Engineering,

JNTUACE Anantapuramu, Andhra Pradesh

ABSTRACT

In the present investigation, work strength and workability characteristics of self-curing concrete are to be better found

and which can be compared with conventional concrete of related mix design. The investigational study is approved out

to examine the use of water retains by admixtures as self-curing agent. The properties of concrete are studied at

variouspercentages ofadmixtures which are additional to the concrete mix by weight of cement. The greatest size of

16mm and 10mm coarse aggregates which are available locallyand these aggregates are used in the present work. The

concrete mix is arranged by adding the different ingredients such as cement, fine aggregate, coarse aggregate and

admixture as per mix proportion. The various ingredients are weighed according to the mix proportionM60.

The specimen of cube were tested for 3, 7 and 28 days with each proportion of PVA by using Slump cone test,

Compaction test and Compression test to find their strength and workability of the concrete.

Keywords: Polyvinyl Alcohol, Self Curing agent, Water retentively

1. INTRODUCTION

Concrete curing is in goodsupport of maintaining adequate wet content in concrete for the duration of its early

stages to develop the desired properties.The plan of self-curing agents is to decline the water evaporation from

concrete and hence increases the water preservation capacity of the concrete.

The merit of self-curing admixtures is more considerable in different wasteland places anywhere water is not

sufficiently available. curative is the mainly significant progress in concrete construction.Since the hydration

of cement does take time – days, and weeks rather than hours – curing must be undertaken for a reasonable

period of time if the concrete is to achieve its potential strength and durability.

Curing may also encompass the control of temperature since this affects the rate at which cement hydrates.

The curing period may depend on the properties required of the concrete, the purpose for which it is to be

used, and the ambient conditions like temperature and relative humidity of the surrounding atmosphere.

Curing is the process which controls the rate and extent of wetness loss from concrete during cement

hydration. It may be either after it has been placed in position there by given that time for the hydration of the

cement to occur.The curing stage which can depend on the properties required of the concrete, the purpose for

which it is to be used, and the ambient conditions, i.e. the temperature and relative humidity of the

surrounding atmosphere.

2. PROPERTIES OF MATERIALS

2.1 Polyvinyl alcohol as self curing agent:

The admixture such as polyvinyl alcohol which is formed commercially from the compound of

polyvinyl acetate, regularly by a nonstop process. It isafragrance-free and flavourless, clear and white

coloured granular powder.




Figure 2.1 Sample of polyvinyl alcohol

It dissolves in water, partially soluble in ethyl alcohol, but in soluble in different Organic solvents. Classically

a 5% solution of polyvinyl alcohol exhibits a PH from the range of 5.0 to 6.5 Poly vinyl alcohol has a melting

point of 180 to 190⁰C.It has outstanding emulsifying and gumproperties.PVA is fully degradable and

dissolves quickly.

2.2 Fine aggregate (Sand):

The sand used for the experimental programme was locally available and conformed to Indian Standard

Specifications IS: 2386-2013. The sand was first sieved through 4.75 mm sieve to remove any particles

greater than 4.75 mm. Properties of the fine aggregate which is used in the experimental work are tabulated in

the below table 2.1. The fine aggregated belonged to grading zone II.

Figure 2:2 Sample of a fine aggregate

Table 2.1 Properties of fine aggregate

S.No Characteristics Value Specificationsas Per BIS

(IS 2386-2013)

1 Specific gravity 2.343 2.5-3.0

2 Fineness modulus 3.015 2.2-3.6

3 Grading zone II -

4 Bulk density 16.70 KN/m3

-

5. Bulking of sand 27.53% <40%

2.3 Cement

Ordinary Portland cement of grade 53 ACC cement was used for casting cubes, cylinders and beams for all

concrete mixes. The cement was of uniform colour i.e. grey and was free from any hard lumps. Summary of

the various tests conducted on cement are given in the below figure.




Figure 2:1 Sample of cement

Table 2.1 Properties of Cement

S.No Characteristics Values

obtained

Specifications

AS Per BIS (IS 2386-2013)

1 Specific gravity 3.24 3.0-3.15

2 Normal Consistency 26.5% -

3 Initial Setting time 39 min Not be less than 30 minutes

4 Final Setting time 185 min Not be greater than 600 minutes

5 Fineness of cement(m

2)

289 225

6 Fineness 3% Less

7 Sound ness:

LeChatelier expansion (mm) 1.0 Less than 10

2.4 Aggregates

The material which is retained on 4.5 mm sieve number IS 480 is termed as a coarse aggregate. The broken

stone is generally used as a coarse aggregate. The nature of work decides the maximum size of the coarse

aggregate. Locally available coarse aggregate having the maximum size of 16mm, 10 mm was used in this

work. The aggregates were washed to remove dust and dirt and were dried to surface dry condition. The

aggregates were tested as per Indian Standard Specifications BIS: 2386-2013 [3, 4]. The sieve shaker

apparatus used for the sieve analysis of aggregates. Crushed angular aggregates with maximum grain size of

16 mm, 10mm and downgraded were used and having following properties is shown in the below table.

Figure 2:2 Sample of granite aggregate




Table 2.2 Properties of coarse aggregates

S.NO

Particulars

Results

Specifications

AS Per BIS (IS 2386-2013)

1 Specific gravity

a)16mm

b)10mm

2.629

2.74

2.5-3.0

2 Fineness modulus 2.08 5-8

3 Flakiness index 18.96% Shall not exceed 40%

4 Elongation Index 24.64% Shall not exceed 40%

5 Crushing value 20% Shall not exceed 45%

6 Impact value 20.36% Shall not exceed 45%

7 Water Absorption 0.50% 0.1-2.0%

3. DETAILS OF SPECIMENS

3.1For Cube:

Figure 3:3 Specimen of Cube

Volume of cube =150x150x150

= 0.0033m3

The material is to be used for casting of concrete cube the quantity of material is

Cement : 425x0.0033 = 1.4025kgs

Fine aggregate : 653x0.0033 =2.1549kgs

Coarse aggregate

a) 16mm : 725x0.0033=2.3925kgs

b) 10mm : 483×0.0033=1.593kgs

Water : 148.8x0.0033=0.49104 litre

4. TESTS ARE CONDUCTED

4.1 Slump Cone Test

The concrete slump test is an empirical test that measures the workability of fresh concrete. More specifically,

it measures the consistency of the concrete in that specific batch. This test is performed to check the




consistency of freshly made concrete. Consistency is a term very closely related to workability. It is a term

which describes the state of fresh concrete.

It refers to the ease with which the concrete flows. Workability of concrete is mainly affected by consistency

i.e. wetter mixes will be more workable than drier mixes, but concrete of the same consistency may vary in

workability. It is also used to determine consistency between individual batches. The test is popular due to

the simplicity of apparatus used and simple procedure.

The apparatus for conducting the slump test essentially consists of metallic mould in the form of a

frustum of a cone having the internal dimensions which are given below. The slump cone figure has been

shown in the below figure.

Bottom Diameter :20 cm

Top Diameter : 10 cm

Height : 30 cm

Figure 4:1 Slump Cone

4.2 Compaction Factor Test

The compacting factor test is designed primary for use in the laboratory but it can also be used in the

field. It is more precise and sensitive than the slump test and is particularly useful for concrete mixes of very

low workability. Such dry concrete are insensitive to slump test. The diagram of the apparatus is shown in

figure 3.8. The compacting factor test has been developed at the road research laboratory U. K. and it is

claimed that is one of the most efficient tests for measuring the workability of concrete. This test works on the

principle of determining the degree of compaction achieved by a standard amount of work done by allowing

the concrete to fall through a standard height. The degree of compaction called the compacting factor is

measured by the density actually

achieved in the test to density of same concrete fully compacted. The top surface of the fully compacted

concrete is then carefully struck of level with the top of the cylinder and weighed to nearest 10gms. The

weight is known as “weight of fully compacted concrete”.

𝐂𝐎𝐌𝐏𝐀𝐂𝐓𝐈𝐎𝐍𝐅𝐀𝐂𝐓𝐎𝐑 =weight of partially compacted concrete

weight of fully compacted concrete

It can be realised that compacting factor test measures the inherent characteristics of the concrete which

relates very close to the workability requirements of the concrete and as such it is one of the good tests to

depict the workability of concrete.




Figure 4:2 Compacting Factor

4.3 COMPRESSION TEST

Compression test is the most frequent test conducted on hardened concrete, partly because it is an easy to

perform, and partly because most of the desirable characteristic properties of concrete are qualitatively related

to its compressive strength [5,6]. The compression test is carried out on specimen cubes in shape. Prism is

also sometimes used, but it is not common in our country. Sometimes, the compression strength of concrete is

determined using parts of a beam tested in flexure.

The cube specimen is of the size 15x15x15cm. If the largest nominal size of the aggregates does not exceed

16mm, 10cm size cubes may also be used as alternative cylindrical tests specimens have a length equal to

twice the diameter. They are 15 cm in diameter and 30 cm long. Smaller test specimens may be used but a

ratio of diameter of the specimen to maximum size of aggregate should not be less than 3 to 1 are maintained.

Figure 4:3Compression Test on Cubes

5.RESULTS AND DISSCUSION

5.1 SLUMP CONE TEST

Table 5-1 Slump characteristics

S:NO % Of PVA SLUMP VALUES

1 0 4

2 0.03 9

3 0.06 11

4 0.12 13

5 0.24 15




Figure 5:1 Variation of slump values with % of PVA added to concrete

From the table and graphs shows the values of slump the concrete mix prepared by adding the 0.24%

by the PVA is having the more slump value [1,2]. It means it is more workable. If there is a need of concrete

which should have a high workability the mix with 0.24% PVA can be adopted. But through graphs we cannot

judge the exact % at which the workability is highest. Through the graph it can be said that the highest

workable mix can be get at the percentage between 0.12 and 0.24.

5.2 COMPACTING FACTOR

Table 5-2 Compaction Values

Sr. No % of PVA by the weight of

cement

COMPACTION

VALUE

1. Conventional 0.84

2. 0.03 0.91

3. 0.06 0.91

4. 0.12 0.92

5. 0.24 0.94

Figure 5:2 Variation of Compaction factor values with % of PVA added to concrete

0

2

4

6

8

10

12

14

16

0 0.03 0.06 0.`12 0.24

Slu

mp

Val

ues

% of PVA

0.8

0.82

0.84

0.86

0.88

0.9

0.92

0.94

0.96

0 0.03 0.06 0.12 0.24

Com

pac

tion v

alues

% of PVA




The compacting factor for the concrete mix gradually increased with the increase in % of PVA added up to

0.24% of weight of cement.

As the above table and graphs shows the concrete mix prepared by adding the 0.24% of PVA is

having the more compacting factor[8]. It means it is more workable. If there is a need of concrete which

should have a high workability the mix with 0.24% PVA can be adopted.

But through graphs we cannot judge the exact % at which the workability is highest. Through the graph it can

be said that the highest workable mix can be get at the percentage between 0.03 and 0.24. But through our

experiment we adopt that high compacting factor mix can be obtained by replacing 0.24% of fine aggregate

by PVA.

High compacting factor can be seen in the concretes with 0.24% of PVA added by the weight of the

cement in concretes[9].

5.3COMPRESSIVE STRENGTH

Table 5-3 Compressive Strength of all Samples

Samples % of PVA

Compressive Strength at 28

days (N/mm2)

28 days 7 days 3days

Sample (a) 0 64.93 46.25 34.47

Sample (b) 0.03 68.1 46.34 35.4

Sample (c) 0.06 61.9 44.1 32.5

Sample (d) 0.12 69.9 48.5 36.42

Sample (e) 0.24 72.0 51.2 37.8

Figure 5:1 Compressive strength of a cube at different percentages of PVA

The compressive strength for the concrete mix gradually increased with the increase

in % of PVA added up to 0.24% of PVA.As the table and graphs shows the concrete mix prepared by

replacing the 0.24%of PVA is having the more compressive strength. If there is a need of concrete with high

compressive strengths in same grade of concrete the mix with 0.24% PVA can be adopted. But through graphs

we cannot judge the exact % at which the compressive strength is highest. Through’ the graph it can be said

that the high compressive strength mix can be get at the percentage between 0.06% and 0.24%. But through

30

35

40

45

50

55

60

65

70

75

80

0 0.03 0.06 0.12 0.24

Co

mp

ress

ive

stre

ngth

N

/mm

2

% of PVA

Compressive strength of cube

3days

7days

28days




our experiment we adopt that high compressive strength mix can be obtained by replacing 0.24% of fine

aggregate by PVA[7]. High compressive strength can be seen in the concretes with 0.24% of PVA.

6. ADVANTAGES OF SELFCURING

To rise above from deficiency of external curing generated by both human and hydration.

To eliminate shrinkage (most probably autogenous shrinkage).

Provides moisture contents to keep continue hydration of cement.

Internal curing is a method to provide the water to hydrate all the cement, accomplishing what the mixing

water alone cannot do.

Increase/maintain the strength of concrete if the optimum dosage of self curing admixtures is used.

Protects by reflecting sun rays to keep the concrete surface cooler and prevent excessive heat buildup,

which can cause thermal cracking.

Furnished as a ready to use, true water based compound, produces hard, dense concrete, minimize hair

cracking, thermal cracking, dusting and other defects.

Offers a compressive strength significantly greater than improperly or uncured concrete.

Improves resistance to the abrasion and corrosive actions of salts and chemicals.

7. CONCLUSIONS

Addition of 0.24 %PVA to the concrete mix by the weight of cement gives the compressive strength same

as the conventional mix and more workable than conventional mix.

The concrete mix is more workable when 0.24% of PVA [8,9] added to concrete mix by weight of cement

as the slump values and compacting factor values are high when compared to conventional mix.

The concrete mix prepared by addition of 0.24% of PVA by weight of cement can be used where water is

scarce and unavailable.

Finally the concrete mix with 0.24% of PVA gives the best self curing concrete mix with high

compressive strength and high workability.

6. REFERENCES

1. Titford, E.M. The Golden Age of Concrete. London 1964 British Standards Institution. BS 1881: Part 2: 1970.

Testing Fresh Concrete. British Standards Institution. BS 1881: Part 102: 1983. Testing Concrete. Method of

determination of Slump

2. British Standards Institution. BS EN 12350-2: 2009. Testing Fresh Concrete – Part 2: Slump Test.

3. NageshTatobaSuryawanshi Assessment of the properties of self-cured concrete, Indapur Pune.

4. American Society of Testing Materials. C143/C143M – 10a. Test for the Slump of Hydraulic Cement Concrete.

5. Amin Noushini ,BijanSamali, Kirk Vessalas, Effect of polyvinyl alcohol (PVA) fibre on dynamic and material

properties of fibre reinforced concrete, Centre for Built Infrastructure Research (CBIR), School of Civil and

Environmental Engineering, University of Technology Sydney, AustraliaConstruction and Building Materials 49

(2013) 374–383.

6. Praveen Kumar and S. K. Kaushik (2004), “High strength concrete with ternary blend of fly ash and micro-silica”

Proceedings of ICFRC International Conference on Fiber Composites, High performance concretes and Smart

materials, 8-10 January 2004, Chennai, India, pp.883-892.

7. Krishnan (2001), “New materials and high strength concrete”, Workshop on concrete mix design, 22-24, January

2001, pp. 34-43.

8. Ansari, F. & Li, Q. (1998): “High-Strength Concrete Subjected to Tri axialCompression.”ACI Materials Journal,

Nov.-Dec., Title no. 95-M75, pp. 747-755.

9. Rao G.T and Andal T.,2002, A study of behavior of concrete with stone sand replacing river sand. National

conference on advances in construction materials, ACIM, Harmipur, H.P, Pp 196-201.

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