STRENGTH ANALYSIS OF CONCRETE

USING M-SAND AND COCONUT SHELL

BY,

ALWIS DEVA KIRUPA J.P

1st YEAR ME (STRUCTURAL ENGINEERING)

REGIONAL CENTER OF ANNA UNIVERSITY,

THIRUNELVELI.

INTRODUCTION

Concrete is the widely used building material in

Civil Engineering constructions because of its

versatility.

River sand, a natural resource and a main

constituent of conventional concrete, is

increasingly depleting nowadays due to illicit sand

mining from river.

Dwindling sand resources poses the

environmental problem and hence government

restrictions on sand quarrying resulted in scarcity

and significant increase in its cost

Scarcity of natural sand due to heavy demand in

growing construction activities forces us to find

the suitable substitute.

Replacing fine aggregate by Manufactured sand

(M-sand) in concrete is a better solution for this

ecological imbalance and economic construction.

Utilizing coconut shell as coarse aggregate in

concrete production not only solves the problem of

disposing this solid waste but also helps to

conserve natural resources. Use of coconut shell in

concrete reduces its density.

The strength of the light weight concrete made by

using M-sand and coconut shell at certain

percentage is equal to the conventional concrete.

Materials used1. CEMENT

For general purpose of ordinary Portland cement

43grade is suitable for the construction of all

engineering works.

Properties of ordinary Portland cement:-

As per IS 269-1967-1975 ,

The fineness residue does not exceed 10% on is

sieve no 90µ.

Soundness of ordinary Portland cement is not

more than 10mm in Le-chatterer apparatus.

Initial setting time is not less than 30 minutes.

Final setting time not more than 10 hours.

Compressive strength after 3days is not less

than11.5N\mm2.

Strength after 7 days is not less than 17.5N\mm2.

2. FINE AGGREGATE

2.1 River Sand

River sand shall conform to IS:383 and relevant

portion of IS:515.It shall pass through the 4.75mm

IS sieve leaving a residue of not more than 5%.

2.2 M-sand

M-sand is a term used for aggregate materials less

than 4.75mm size which are processed from

crushed rock or gravel.

The crushed sand or M-sand range should pass

through 10mm IS sieve and retain on 75µm IS sieve.

Fig 1. M-Sand

3. COARSE AGGREGATE

3.1 Crushed or broken stone

It shall be obtained from crushing Granite, trap or

similar approved stone from approved quarry and

shall be conformed to IS 383 and IS 515. 95% of

which shall be retained on 4.75mm IS sieve. Size of

course aggregate shall be 20mm. Should be cubical

in shape.

3.2 Coconut shell

Coconut shell is one of agricultural by-product.

They were sun dried for 1 month before being

crushed manually. The crushed materials were later

taken to the lab where it is processed. The particle

size of the coconut shell is range from 5 to 20mm.

Fig 2. Coconut Shell

4. WATER

Water used for mixing and curing shall be clean

free from oils, acids, alkalis, salts, sugar, organic

materials or other substances that may be

deleterious to concrete. Portable water is

generally considered satisfactory for mixing

concrete. Water used in concrete is of PH

value is

not less than 6.

Mix designThe process of selecting suitable ingredients of

concrete and determining their relative amounts

with the objective of producing a concrete of the

required, strength, durability, and workability as

economically as possible, is termed the concrete

mix design.

Factors affecting the mix design

Compressive Strength

Workability

Durability

Maximum Nominal Size of Aggregate

Grading and Type of Aggregate

Quality Control

PROCEDURE

Design stipulations for proportioning

a. Grade designation: M20

b. Type of cement: OPC 43 grade, IS 8112

c. Max. nominal size of agg. : 20 mm

d. Minimum cement content: 320 kg/m3

e. Maximum water cement ratio: 0.55

f. Workability: 75 mm (slump)

g. Exposure condition: Mild

h. Degree of supervision: Good

i. Type of agg. : Crushed angular agg.

j. Maximum cement content: 450 kg/m3

k. Chemical admixture: Not used

1. Target strength for mix proportioning

fck’= fck+ks

By Table 8 of IS 456 2000 standard deviation s = 4

Hence target strength = 20+1.65 x4 = 26.60 N/mm2

2. Selection of w/ c ratio

From Table 5 of IS 456:2000, maximum water

cement ratio = 0.55 (Mild exposure)

Based on experience, water cement ratio is 0.50

0.5 < 0.55. Hence, water cement ratio is 0.5

3. Selection of water content

From Table 2, maximum water content = 186 litre

Estimated water content for 75 mm slump

= 186 + 3/100 x 186 = 191.6 litres

4. Calculation of cement content

Water cement ratio = 0.50

Cement content = 191.6/0.5

=383 kg/m3 >320 kg/m3

(given)

From Table 5 of IS 456, minimum cement content for

Mild exposure condition = 300 kg/m3

Hence Cement content is taken as 383kg/m3

5. Proportion of volume of coarse aggregate and

fine aggregate content

From Table 3, volume of coarse aggregate

corresponding to 20 mm size aggregate and fine

aggregate (Zone I) for water-cement ratio of 0.50

= 0.60

6. Mix calculations

The mix calculations per unit volume of concrete

shall be as follows

a) Volume of concrete = 1 m3

b) Volume of cement =(mass of cement/specific

gravity of cement ) x (1/1000)

= [383.16/3.15] x [1/1000]

= 0.122 m3

c) Volume of water = [192/1] x [1/1000]

= 0.192 m3

d) Volume of all aggregates (e) = a – (b + c)

= 1 – (0.122 + 0.192) = 0.686 m3

e) Volume and weight of coarse aggregates

Volume = 0.686 x 0.6 = 0.412 m3

Weight = Volume of CA x specific gravity of CA

= 1103 kg

f) Volume and weight of fine aggregates

Volume = e x Volume of FA x specific gravity of FA

= 0.686 x 0.4 = 0.274 m3

Weight = Volume of FA x specific gravity of FA x1000

= 727 kg

7. Mix proportions for trial number 1

Cement = 383 kg/m3

Water = 191.6 kg/m3

Fine aggregate = 727 kg/m3

Coarse aggregates = 1103 kg/m3

Water cement ratio = 0.50

Yield = 2404.6 kg

Water : Cement : Fine aggregate : Coarse aggregate

191.6 : 383 : 727 : 1103

0.5 : 1 : 1.89 : 2.88

Mix ratio 1: 1.89: 2.88

Sample Specific gravity

River sand 2.46

M-sand 2.52

Coarse aggregate 2.61

Coconut shell 1.2

Results & discussions1. SPECIFIC GRAVITY

The specific gravity of fine aggregates and coarse

aggregates are shown in Table 1. The average specific

gravity of natural aggregates lies between 2.6 and 2.8.

Table 1 : Specific Gravity of Aggregates

2.462.52 2.61

1.2

0

0.5

1

1.5

2

2.5

3

River sand M-sand coarse agg. coconut shell

spec

ific

gra

vit

y

specific gravity

Fig 3. Specific Gravity of Aggregates

Designation Concrete sample Slump value (mm)

C Conventional concrete 63.33

A1 100% M-sand concrete 60

A2 100% M-sand + 30% CS 8.33

A3 100% M-sand + 20% CS 24

A4 100% M-sand + 10% CS 48.33

2. SLUMP VALUE

Slump test was conducted on the fresh concrete. The slump

values of conventional concrete & M-sand with coconut shell

concrete are shown in table 2

Table 2 Slump Values of Conventional, M-Sand and Coconut

Shell Concretes

0

10

20

30

40

50

60

70

C A1 A2 A3 A4

63.33

60

48.33

24

8.33

slump in mm

Fig 4. Slump Value of Conventional, M-sand and CS

Concretes

Designation Concrete sample Density(kg/m3)

C Conventional concrete 2388

A1 100% M-sand concrete 2427

A2 100% M-sand + 30% CS 2244

A3 100% M-sand + 20% CS 2262

A4 100% M-sand + 10% CS 2296

3. DENSITY OF SAMPLE

The density of different concrete samples was

obtained as shown in table 3.

Table 3. Density of concrete Sample

The density of conventional concrete was obtained as

2388kg/m3. The density of M-sand concrete was found as 2427

kg/m3. When compared, it is 2% greater than conventional

concrete.

The density of 30% coconut shell concrete was found to be

2244kg/m3, it is 6% lesser than the density of conventional

concrete.

The density of 20% coconut shell concrete was found to be

2262kg/m3, it is 5% lesser than the density of conventional

concrete.

The density of 10% coconut shell concrete was found to be

2296kg/m3, it is 4% lesser than the density of conventional

concrete.

The variations of density of different concrete samples are

shown in figure 5

2150

2200

2250

2300

2350

2400

2450

C A1 A2 A3 A4

DE

NS

IT

Y(K

G/M

3)

DENSITY

Fig 5. Density of Concrete Sample

7 days compressive strength

(N/mm2)

21 days compressive

strength (N/mm2)

28 days compressive

strength (N/mm2)

Sampl

e 1

Samp

le 2

Samp

le

3

Averag

e

Sampl

e 1

Samp

le 2

Sampl

e

3

Averag

e

Sampl

e 1

Sample

2

Sample

3

18.22 17.78 19.56 18.52 23.56 24.22 23.33 23.72 25.56 24.44 26.22

23.77 24.66 24.22 24.22 28 30.89 28.44 29.11 36.67 35.56 36

13.11 13.33 13.56 13.33 21.11 20 20.67 20.59 22.22 21.56 22.67

15.56 15.11 15.56 15.41 23.78 24.44 22.44 23.56 25.33 25.11 24.67

18.67 19.33 19.11 19.04 25.78 26 24.89 25.56 27.11 26.67 27.78

Table 4. Compressive Strength of Different

Concrete Samples

18.52

24.22

13.33

15.41

19.04

0

5

10

15

20

25

30

C A1 A2 A3 A4

CO

MP

RE

SS

IV

E S

TR

EN

GT

H(N

/𝐦𝐦

2)

Fig 6 : 7 Days Compressive Strength

23.72

29.11

20.59

23.56

25.56

0

5

10

15

20

25

30

35

C A1 A2 A3 A4

CO

MP

RE

SS

IV

E S

TR

EN

GT

H(N

/𝐦𝐦

2)

Fig 7 : 21 Days Compressive Strength

25.38

36.07

22.44

25.04

27.19

0

5

10

15

20

25

30

35

40

C A1 A2 A3 A4

CO

MP

RE

SS

IV

E S

TR

EN

GT

H(N

/𝐦𝐦

2)

Fig 8 : 28 Days Compressive Strength

0

5

10

15

20

25

30

35

40

C A1 A2 A3 A4

CO

MP

RE

SS

IV

E S

TR

EN

GT

H(N

/M

M2)

7 DAYS COMPRESSIVE STRENGTH

21DAYS COMPRESSIVE STRENGTH

28DAYS COMPRESSIVE STRENGTH

Fig : 9 Comparison of 7, 21 and 28 Days Compressive

Strength

conclusionThe availability of river sand is very scarce

nowadays. M-sand fulfill the requirement of sand in

concrete.

The compressive strength of concrete using M-

sand is high when compared to concrete made by

river sand.

By replacing 20% coconut shell in place of

coarse aggregate, concrete has 9% lesser density

compared to conventional concrete.

Compressive strength of concrete made by using

the M-sand and 20% coconut shell is nearly equal

to the strength of conventional concrete.

The compressive strength of conventional concrete

was found as 25.38N/mm2

whereas the compressive

strength of full replaced M-sand concrete was found

as 36.07N/mm2.

While replacing 20% coarse aggregate by coconut

shell in M-sand concrete the strength was found as

25.04N/mm2. This value is nearly equal to the

conventional concrete and also that density was 5%

lesser than conventional concrete.

..