Journal of Research in Engineering and Applied Sciences

JREAS, Vol. 1, Issue 04, Oct. 2016172

STRENGTH PROPERTIES OF PARTIALREPLACEMENT OF COCONUT SHELLS AS

COARSE AGGREGATE IN CONCRETE1 2K. Rajasekhar and K. Spandana

1Assistant Professor, Department of Civil Engineering, Krishna Chaitanya Institute of Technology & Sciences, Markapur, Andhrapradesh, India

2 PG student, Department of Civil Engineering, Krishna Chaitanya Institute of Technology & Sciences, Markapur, Andhrapradesh, India

1 2{Email: sekhar.raj541@gmail.com, spandana.kande@gmail.com}

Abstract

Concrete is a group of raw materials similar in appearance and properties to some natural lime stone rock. It is a man-made mixture, the major constituent is natural coarse aggregate such as gravel or crushed rock, fine aggregate such as sand and cement powder all mixed with water. As the time goes on, the cement paste starts it process of hydration and after hardening it gets its required strength to withstand the load. The coconut shells used as replacement for coarse aggregate has never been usual practice in particular areas where light weight concrete is required for non-bearing walls, non-structural floors and in strip footings.Because of the high cost of construction, if we use waste materials as replacement materials in the construction of concrete structures, the cost of construction will be reduce. By the replacement of coconut shells we can get the light weight concrete. As the replacement of coconut shells increases the strength of the concrete will be reduce. The strength properties of concrete were found by the replacement of coconut shells by 0%, 5%, 10%, and 15% at the age of 3days, 7days and 28days. This type of concrete can be treated as eco-friendly concrete.

Key Words : Coarse aggregate, Crushed coconut shell, Compressive strength, Split tensile strength, Waste utilization.

1. Introduction

Concrete is a composite material which composed of aggregates, cement and water. Concrete is used more than any other manmade material in the world. In addition, concrete is the 2nd most consumed substance in the world-behind water. About 7.23 billion tons of concrete is produced every year. The planet production of concrete is increasing due to high growth of infrastructure development and construction activities in the world Production of concrete demand its constituents like aggregates, cement, water and admixtures. Sources of conventional aggregates occupy the major part of the concrete. The large scale production of concrete in construction activities using conventional coarse aggregate such as granite immoderately reduces the natural stone deposits and affecting the environment hence causing ecology im-balance. Increasing demand of natural aggregates show that crushed stone demand will be 2050 million metric tons in 2020. This huge demand of natural aggregate raises a serious question about preservation of natural aggregate sources for sustainable development. Extraction and processing of aggregates is also a major concern for environment. Therefore consumption of alternative waste material in place of natural aggregate in concrete production not only protects environment but also makes concrete a sustainable and environment friendly construction material. Different waste material like rubber, fly ash, glass, bottom ash, artificial sand etc has been used as alternative for replacing natural aggregates. Apart from the above mention waste material, a few studies shows that

agriculture waste coconut shell can also use as coarse aggregate for concrete.

1.1. Coconut Shell

Coconuts are referred to as "man's most useful trees", "king of the tropical flora" and "tree of life". Coconuts or its scientific name “cocos-nucifera” are the most important of cultivated palms and the most widely distributed of all palms. Coconut is a tall cylindrical-stalked palm tree, reaching 30 m in height and 60-70 cm in diameter. It is a tropical plant for low altitudes. It needs sunshine and a soil rich in calcium and phosphorus, and is thus generally suitable for cultivation in sandy seashore.

The coconut industry in India accounts for over a quarter of the world's total coconut oil output and is set to grow further with the global increase in demand. However, it is also the main contributor to the nation's pollution problem as a solid waste in the form of shells, which involves an annual production of approximately 3.18 million tones.

Fig. 1 Coconut Shells

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1.2. Collection of Coconut Shell

The coconut shell is obtained from nearby temple at Markapur Sri Kashinayana Asramam. After collecting the coconut shell it split into the small pieces by using the hand hammer. After that the shells will be sieved from 12mm sieve to avoid the flakiness property of the coconut shell. Then it will be replaced as coarse aggregate with 0%, 5%, 10%, and 15% respectively.

(1) Collection of coconut shell (2) Crushing into pieces

(3) sieving from 12mm sieve

1.3. Aims of the Research

1. Analyzing split tensile strength and compressive strength characteristics of with partial replacement using M25 grade concrete.

2. Main aim to show that coconut shell aggregate is a light weight construction and simultaneously reduces the environmental problem of solid.

2. Experimental Investigation

The present investigations are aimed to study Basic Studies of coconut shell concrete by weight of cement with different W/C ratios 0.45 with coconut replacement 0%, 5%, 10% and 15% after the age of 28 days only.

2.1. Cement

Locally available 53 grade of Ordinary Portland Cement (KCP India PVT Ltd.) confirming to IS: 12269 was used in the investigations. Table 4.1gives the physical properties of OPC used in the presentinvestigation and they conform to IS specifications.

Table 1 : Physical properties of cement

S.No. Physical properties Testresult

1.

2.

3.

4.

5.

6.

Standard consistency

Initial setting time

Final setting time

Fineness

Specific Gravity

Compressive Strength

33%

95 min

300 min

6%

3.01

48.35Mpa

2.2. Aggregate

The size, shape and gradation of the aggregate play an important role in achieving a proper

concrete. The flaky and elongated particles will lead to blocking problems in confined zones. The sizes of aggregates will depend upon the size of rebar spacing.

Table 2 : Physical properties of coarse aggregate

S.No Physical property Test result

1 Maximum Size (mm) 20

2 Fineness modulus 4.189

3 Specific Gravity 2.70

4 Bulk Density(kg/m3)

a)Loose b) Dense

1480kg/m3

1610kg/m3

5 Water Absorption 1%

6 AggregateCrushing Value 16.60%

7 Aggregate Impact Value 11.01%

2.3. Fine Aggregates

The locally available sand is used as fine aggregate in the present investigation. The sand is free from clayey matter, salt and organic impurities. The sand is tested for various properties like specific gravity, bulk density etc., and in accordance with IS 2386-1963. The fine aggregate is conforming to standard specifications.

Table 3 : Physical properties of fine aggregate

S.No Physical property Test result

1. Fineness modulus 2.23

2. Specific Gravity 2.61

3. Bulk Density

(a) loose

(b) compacted

1530 kg/m3

1600 kg/m3

4. Water Absorption 0.80%

Fig. 2 : Collection of Coconut Shells

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Table 4 : Sieve analysis of 20mm coarse aggregate Sample 5000 gms.

S.No IS Sieves size

Wt. Retained (gms.)

Cumulative wt. Retained (gms)

Cumulative % of wt. Retained % Passing

1 40 mm 0 0 0 100

2 20 mm 915 915 18.30 100

3 10 mm 3994 4909 99.09 81.7

4 4.75mm 45 4954 100 0.92

5 2.36 mm 0 5000 100 0

6 1.18 mm 0 5000 100 0

7 600 µ 0 5000 100 0

8 300 µ 0 5000 100 0 9 150 µ 0 5000 100 0

Total 5000 717.38

Fineness modulus of Coarse aggregate=717.38/100 =7.1

S.No. IS Sieve Size Wt.Retained (gms)

Cumulative Wt. Retained (gms)

Cumulative % of wt. Retained

% Passing

1 4.75 mm 3 0.3 0.3 99.7

2 2.36 mm 4 0.4 0.7 99.3

3 1.18 mm 82 8.2 8.9 91.1

4 600µ 318 31.8 40.7 59.3

5 300µ 499 49.9 90.6 9.4

6 150µ 68 6.8 87.4 2.6

7 <150µ 3 0.3 97.7 2.3

Total 1000 -- 238.6 --

Fineness modulus fine aggregate = 238.6/100 = 2.384

S.No. Physical property Test result

1 Maximum Size (mm) 20

2 Fineness modulus 6.48

3 Specific Gravity 1.26

4 Bulk Density(kg/m3)Loose Dense

510600

5 Water Absorption (%) 6

6 Aggregate Crushing Value (%) 2.49

7 Aggregate Impact Value (%) 8.55

8 Moisture Content (%) 4.2

9 Shell Thickness(mm) 3

2.4. Coconut shells

In this work coconut shell was used as partial replacement of coarse aggregate which is crushed granite. Coconut shell needs no pre treatment, except for water absorption. Coconut shell has very high water absorption. Due to this property, before use coconut shells were soaked in potable water for 24 hours. After that it is replaced in coarse aggregate with 0%, 5%, 10%, and 15% in concrete.

2.5. Mixing

Mixing of ingredients is done in a rotating drum. Mixing will be done by concrete mixer, using rotated wheel. The cementations materials are thoroughly blended with hand and then the aggregate is added and mixed followed by gradual addition of water and mixing.

M-25 grade of concrete was designed according to I.S 10262-1982 method. The crushed granite aggregates were replaced as 0%, 5%, 10%, and 15%. The test results

Table 5 : Physical properties of the coconut shell

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were analyzed and compared with control concrete that is made with replacement of coarse aggregate. By reason of high water absorption of coconut shell, it was pre-soaked in water for 24 hours, earlier than mixing.

For W/C ratio 0.45 Ordinary Concrete mix proportion is 1: 1.62: 2.77

2.6. Workability Test

Immediately after mixing each of concrete, was tested for workability by Vee- bee apparatus, slump, compaction factor tests in the laboratory.

S.No Workability Test 0% 5% 10% 15%

1 Slump (mm) 110 170 160 150

2 Compaction Factor

0.91 0.77 0.83 0.65

Fig. 5 : Slump Compaction Factor

S. No

Coconut shell concrete V-bee

Time in Sec

Degree of Workability W/B

% of replacement of coconut

shell

1.

0.45

0 2.5 Medium

2. 5 3.0 Medium

3. 10 3.0 Medium

4. 15 4.0 Medium

2.7. Workability of Coconut Shell Concrete

Workability decreases as the percent of coconut shell replacement increases as the slump factor and compaction factor decreases.

Graph 1: Workability analysis for slump

Graph 2:Workability analysis for compaction factor

3. Compressive Strength of Coconut Shell Concrete (N/mm2) : Values of compressive strength at different percentage of CS

S.No. Days 0% 5% 10% 15%

1 3 25.92 21.55 19.63 17.40

2 7 31.77 30.66 27.79 25.62

3 28 41.1 40.44 35.03 32.94

Graph 3. Compressive strength analysis at the age 3days

Fig. 3 : Mixing

Fig. 4 : Coconut shell concrete

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Graph 4:Compressive strength analysis at the age 7days

Graph 5: Compressive strength analysis at the age 28days

4. Split tensile Strength of Coconut Shell Concrete (N/mm2)

For tensile test cylinders of 150×300 mm2 size were adopted. The tensile strength is one of the basic and important properties of the concrete. The concrete is not usually expected to resist the direct tension because of its low tensile strength and brittle nature. However, the determination of tensile strength of concrete is necessary to determine the load at which the concrete members may crack. The cracking is a form of tension failure.

Values of split tensile strength at different percentage of CS

Days 0% 5% 10% 15%

3 1.55 1.06 0.91 0.84

7 2.82 1.83 1.62 1.41

28 5.09 3.11 2.75 2.54

Graph 6: Split tensile strength analysis at the age of 3days

Graph 7:Split tensile strength analysis at the age of 7days

Graph 8: Split tensile strength analysis at the age of 28days

Fig. 6 : Compressive strength testing machine

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Fig. 7 : Split tensile strength testing machine

5. Conclusions

The following Conclusions are drawn from the Experimental investigation in present work:

Ø It is analyzed that in the replacement of coarse aggregate with coconut shell if we increase the percent of replacement of CS it reduces the compressive strength of the concrete.

Ø Production of Sustainable Light-weight concrete is attained.

Ø Similar to the compressive strength, the split tensile strength also decreased with increase in CS replacement.

Ø Density reduces with at the increase of percentage of replacement of coconut shell.

Ø Workability decreases as the percent of coconut shell replacement increases as the slump factor and compaction factor decreases.

Ø Cost reduction of the construction is observed.

Ø With CS percentage increase the 7 day strength gain also increased with corresponding 28 day curing strength. However, the overall strength decreased with CS replacement when compared to control concrete.

References

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[2] A. GopalCharanBehera, Ranjan Kumar Behera, Coconut Shell as Coarse Aggregate, International Journal of Engineering Research & Technology (IJERT), vol.2, Issue 6, June – 2013.

[3] A. AmarnathYerramalaRamachandrudu C, Properties of Concrete with Coconut Shells as Aggregate Replacement, International Journal of Engineering Inventions, vol.1, Issue 6, October 2012.

[4] Concrete technologyA.M. Neville. Properties of concrete, Person Edition 2006.

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[6] A. Kulkarni V.P, Kumar .S, (2013), “Comparative study on coconut shell aggregate with conventional concrete”, Vol.2, Issue 12, pp 67-70

[7] A.J. P. Ries, J. Speck, (2010), “Lightweight Aggregate Optimizes the Sustainability of Concrete”, Concrete Sustainability Conference, National Ready Mixed Concrete Association.

[8] A. Abdullah A.A.A. et al (1984) “Basic Strength Properties of Light Weight Concrete Using Agricultural Waste as Aggregate” International conference on Low Cost Housing in developing countries,Roorkee,India,pp624-636.

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[14] I.S 456-2000-Indian Standard: Plain and Reinforced Cement Concrete

[15] Indian Standard (IS 383 -1970) Specification for coarse and fine aggregates from natural sources for concrete.