EFFECT OF COCONUT FIBER WASTE, SUGAR CANE MOLASSES ON

STRENGTH OF ORDINARY CEMENT

Abstract:

This research represents the effect of natural fibers content on the physical and

mechanical properties as well as fracture behavior of composite cement reinforced with natural

fibers and its comparison with plain concrete. The mix design was based on 1:2:4 ratio for

cement: sand: coarse aggregate and w/c ratio was used as 0.7. Coconut fibers and sugar cane

molasses was used 0.05% by weight of total.

Samples were cured and tested for 7 and 14 days. It was observed that the composite

reinforced with coconut fiber demonstrated the highest strength and plain cement

demonstrated the lowest one.

From the experimental results it was observed that beam reinforced with coconut fiber

gave high strength values as 258.5MPa (7days modulus of rupture strength) and 387.5MPa (14

days modulus of rupture strength).While beam reinforced with sugar cane molasses gave

intermediate values as 221.5MPa (7 days modulus of rupture strength) and 332MPa (14 days

modulus of rupture strength). Plain cement concrete beam gave lowest values as 221.5MPa (7

days modulus of rupture strength) and 295MPa (14 days modulus of rupture strength).

So it is concluded that if we add coconut fibers to port land cement its strength and

durability increases significantly.

Key words: composite concrete, coconut fiber, sugar cane molasses, super plasticizer, silica

fume, construction materials

Introduction:

Our world has plenty of agricultural waste products such as coconut fibers, rice husk,

sugar cane molasses etc. Among the advantages of these fibers are: renewable, nonabrasive,

cheaper, abundance and show no health and safety problems during handling and processing.

(Zulkifli 2009)

In recent days scientists are working in the utilization of agricultural waste products as

low cost construction materials especially in developing countries. Most recently, there have

been considerable efforts to develop natural-reinforced cementations composites for affordable

infra-structure. (Asasuttjarit, 2009; Penamora, 1997; Asasutjarit, 2007). Among those agricultural

wastes, coconut fiber or coir fiber has the potential to be used as reinforcement in the

development of cement fiber composites. Coconut fiber is the most interesting fiber as it has the

lowest thermal conductivity and bulk density. From previous investigations there is limited

application of coconut fibers except some products based on polymer composite. (Wooly 1997;

Savastano, 1999). From researches it has also been proved that the addition of coconut fiber

reduced the thermal conductivity of the composite samples. (Khedari, 2005; Asasutjarit, 2007;

Asasutjarit, 2009). Some researchers investigated the effect of chemical composition

modification and surface modification of coconut fibers as reinforcement to the mechanical

properties of cement composites. (Asautjarit, 2007). They reported that the mechanical

properties of composites; modulus of rupture and internal bond, increased as a result of chemical

composition, modification and surface modification. (Asasutjarit, 2009). Thermal property of

composites revealed that coconut fiber-based lightweight cement board has lower thermal

conductivity.

The properties of concrete that are affected by adding admixtures are mentioned

as. The mechanical properties of concrete in compression and tension differ from each other.

Concrete is strong in compression, but weak in tension. The tensile strength of concrete is on the

order of 1/10 – 1/20 of its compressive strength. Shrinkage is the decrease in the volume of

concrete during hardening and drying. The increase in volume of concrete due to increase in

temperature is called expansion of concrete. Due to expansion and shrinkage cracks appear on

concrete surface. From our experiments it is seen that by adding agricultural fibers tensile and

compressive strength improves effectively. Also these fibers are found effective in controlling

expansion and shrinkage cracks.

Some researcher investigated on the development of a new type of soil–cement

block using coconut fiber. Various compositions were tested. In their investigation, the use of

coconut fiber as an admixture can reduce the block thermal conductivity and weight. The

compressive strength and thermal conductivity decreased when the quantity of fiber increased.

This paper reports on the development of coconut fiber based composites by conventional

method of mixing and curing process. This research work was aimed to investigate and compare

the potential use of coconut fiber, plain cement and sugar cane molasses.

Materials Description:

Coconut fibers:

Coconut fibers are very important admixtures in strengthening concrete. Fibers

formed bond with concrete and thus a good strength is achieved. It has advantage that it is

environment friendly and economic. Another advantage is that it has lower weight ratio than

other admixtures which contribute to strength. Coconut fibers have no negative effects on any

type of performance of concrete like concrete, corrosion etc. Beside strength, coconut fiber also

can help in reducing the cracking in the concrete can reduced the density of the concrete. Beside

strength, coconut fiber also can help in reducing the cracking in the concrete.

Chemical Properties of coconut fiber: Coconut fibers contain cellulose, hemi-cellulose and lignin as major composition. These

compositions affect the different properties of coconut fibers.

The pre-treatment of fibers changes the composition and ultimately changes not only its properties but also the properties of composites. Some-times it improves the behavior of fibers but sometimes its effect is not favorable.

Physical properties:

Sugar Cane Molasses:

Sugar cane is found very important admixtures in strengthening concrete. Sugar

cane formed bond with concrete and thus a good strength is achieved. It is newly developing idea

and is becoming very popular in research works. It has advantage that it is environment friendly

and economic. Another advantage is that it has lower weight ratio than other admixtures which

contribute to strength. Sugar cane has no negative effects on any type of performance of

concrete like concrete, corrosion etc.

Physical properties of Sugar cane:

Density (g/cm3)

2.52

Blaine surface area (cm2/g)

5140

Particle size (µm) 28.9

Color white

Chemical properties:

Chemical composition (wt. %)

SiO2 62.43

Al2O3 4.38

Fe2O3 6.98 CaO 11.8

MgO 2.51 SO3 1.48

K2O 3.53

LOI 4.73

But the sugar cane contributes less to strength as coconut fibers does.

Chemrite 520 BA (Super Plasticizer):

Chemrite 520 BA High Range Water-Reducing and Set Retarding Concrete Admixture

Table: Properties of chemrite 520 BA (super plasticizer)

[REF: IMPORIENT CHEMICALS (PVT) LTD. GULBERG-III LAHORE-54660 PAKISTAN,

chemrite@brain.net.pk]

Silica Fume:

Fresh concrete containing silica fume is more cohesive and less prone to segregation than concrete without silica fume. Silica fume is very fine non crystalline silica produced in electric arc furnaces as a byproduct of the production of elemental silicon also known as condensed silica fume or micro silica. One of the most beneficial uses for silica fume is in concrete because of its chemical

and physical properties. It is a very reactive pozzolan. Concrete containing silica fume can have

very high strength and can be very durable. Silica fume is available at easy approach and at low

prices. Silica is some time used as a by-weight replacement of cement keeping the certain target

strength.

Product Description

Chemrite 520 BA is used as a highly effective water-reducing agent and super plasticizer for the production of high quality, free flowing concrete. Chemrite 520 BA promotes set retardation followed by high early and ultimate strengths. It is particularly suitable for use in tropical, hot climatic conditions.

Product Data Type Organic polymer blend.

Density at 25°C Approximately 1.18 Kg/Lit.

pH value Approximately 7

Chloride Content Nil (EN 934-2)

Toxicity Non-toxic.

Transportation Non-hazardous

Physical properties:

Procedure:

Samples of beam of standard size 4”x4”x20” (width x depth x length) are prepared. Beam

weight is 18 kg including waste material. The amounts of cement, sand, coarse aggregate and

water are calculated below

Cement : Sand : Aggregate

1 : 2 : 4

Cement = 1/7x18 = 2.57kg

Sand = 2/7x18 = 5.14kg

Coarse Aggregate = 4/7x18 = 10.29kg

Water/ Cement ratio is 0.7

Water = 0.7x2.57 = 1.8kg

Total material used is tabulated below

Sample No.

Description Cement (%age by weight)

Sand (%age by weight)

Coarse Aggregate (%age by weight)

Silica Fume (%age by weight)

w/c ratio

Super Plasticizer (%age by weight of cement)

Coconut fiber (%age by weight)

Sugar Cane (%age by weight)

1 Plain cement beam

13.16% 28.55%

57.16% 2.22%

0.7 0.8% -------- ------

2 Plain Cement beam

13.16% 28.55%

57.16% 2.22%

0.7 0.8% -------- ------

3 Coconut fiber reinf. beam

13.16% 28.55%

57.16% 2.22%

0.7 0.8% 0.05% -------

4 Coconut fiber reinf. beam

13.16% 28.55%

57.16% 2.22%

0.7 0.8% 0.05% --------

5 Sugarcane mol. reinf. beam

13.16% 28.5% 57.16% 2.22%

0.7 0.8% -------- 0.05%

6 Sugarcane mol. reinf. beam

13.16% 28.55%

57.16% 2.22%

0.7 0.8% -------- 0.05%

Table1: Materials used and their weightage

Silica fume is used 2.22% of total weight and is used as a replacement for cement and

its weight is 400 g for each sample. Super plasticizer is used 0.8% of cement and it weighs 21 g

for each sample.

Weighted amount of water is taken in bottle and super plasticizer is added in it in

required quantity. Other contents like coconut, sand, aggregate, silica fume are weighted and dry

mixed with each other by manual or in electric rotating concrete mixer. For manual preparation

a large iron plank is taken and materials are dry mixed with each other with special tools. For

samples of coconut and sugar cane molasses, they are cut into small pieces and dry mixed with

other material.

Now water is added to the dry mixed materials in three steps such that before

applying next amount of water, the paste is homogeneous. In this way a complete homogeneous

paste is prepared. In case of electric concrete mixer, water is added in three steps after short

interval and a homogeneous paste is formed out

Now molds of beam are oiled and homogeneous paste is filled in them in three

layers. After adding each layer sufficient compaction is applied to make it dense enough. Then

samples are left for 24 hours. After 24 hours samples are un-molded and carried to the water

bath for the purpose of curing

Curing:

Curing is the process in which the concrete is protected from loss of moisture and kept

within a reasonable temperature range. The result of this process is increased strength and

decreased permeability. Curing is also a key player in mitigating cracks in the concrete, which

severely impacts durability. Cracks allow open access for harmful materials to bypass the low

permeability concrete near the surface. Good curing can help mitigate the appearance of

unplanned cracking.

For the purpose of curing samples are kept in water bath and one day before testing,

samples are taken out and kept in open air to make it air dry.

Figure: Beams after curing

Testing:

The test procedure to determine strength of beam under loading is two

point load method. The test is performed at 7 day days and 14 days and strength is

checked.

The supports to beam are applied at 2.5” from each side, giving a clear span

of 15”. The loads are applied at 5” distance from each support, giving the distance

between two loads 5”

Figer2: Testing of Beam

Figer3: support conditions and loading pattern

Test Results:

The test results obtained from 7 days and 14 days testing are tabulated below

Day Of Testing

P.C.C Beam (Modulus of rupture)

Beam reinforced with Sugar cane (Modulus of rupture)

Beam reinforced with coconut (Modulus of rupture)

7 Day

221.5MPa

221.5MPa

258.5MPa

14 Day

295MPa

332MPa

387.5MPA

Conclusion:

Behavior of P.C.C Beam:

Strength results of P.C.C beams conducted from experimental test were less

from that reinforced with sugar cane molasses or coconut fibers. It is because of low bond

strength among the aggregate of P.C.C beam. When load is applied, load increase linearly and no

warning cracks occur. When ultimate failure occur P.C.C beam failed suddenly without showing

any warning cracks. The sudden failure occur because the concrete is a brittle material. A material

is brittle if, when subjected to stress, it breaks without significant deformation (strain). Brittle

materials absorb relatively little energy prior to fracture, even those of high strength. Breaking is

often accompanied by a snapping sound.

Figer4: P.C.C beam fails suddenly without giving warning cracks

Graph1: graph between 7 days and 14 days strength of plain cement beam

Behavior of Beam reinforced with sugar cane molasses:

From our tests and their results, it is seen that beams with sugar cane

molasses show no more special behavior other than plain cement concrete beam. Its strength

results were a little bit higher than that of Plain cement concrete beam. The beam reinforced

with sugar cane molasses show little change in failure behavior than plain cement concrete beam.

It is because of addition of fibers of sugar cane molasses. They add a little bit to increase the bond

strength between aggregate. So the beam reinforced with sugar cane molasses is not fully brittle.

When load is applied, load increase linearly and small cracks appear on the beam. On further

loading, the cracks suddenly grow larger and failure of beam occur.

Figer5: Sugar Cane Molasses Reinforced beam shows large cracks ant then fails abruptly

0

50

100

150

200

250

300

350

7 days 14 days

Mo

du

lus

of

Ru

ptu

re M

Pa

Days

Chart Title

Graph2: graph between 7 days and 14 days strength of sugarcane molasses reinf. beam

Behavior of coconut fiber reinforced Beam:

From our test results, it is seen that beams reinforced with coconut fibers show

special behavior in strength and failure mode.

Its strength results were much higher of that concluded from testing of plain

cement beam and sugar cane molasses beam. It is because fibers of coconut play important role

in bonding between concrete aggregate. They form a good bond with aggregate. So due to high

bond strength, its strength results are better than P.C.C beam and sugar cane molasses reinforced

beam. The coconut reinforced beam show a little bit ductile behavior. A ductile material is that

which under loading, shows bending before cracking.

The cracking behavior of coconut reinforced beam is different from P.C.C beam

and sugar cane molasses reinforced beam. When loading is applied, the load increase linearly

and no cracks occur. On further increment of load, the small cracks appear on the beam. The

cracks grow larger with increase of load and then beam fails ultimately.

Graph3: graph between 7 days and 14 days strength of coconut fiber reinf. beam

0

50

100

150

200

250

300

350

7 days 14 days

Mo

du

lus

of

Ru

ptu

re M

Pa

Days

Chart Title

050

100150200250300350400450

7 days 14 daysMo

du

lus

of

Ru

ptu

re M

Pa

Days

Figure6: Coconut reinforced beam show cracks that develop larger with loading and then fails.

Acknowledgement:

Above experimental results demonstrate us the behavior of different

types of beams. Among the three types of beams used as plain cement concrete beam, beam

reinforced with sugar cane molasses and beam reinforced with coconut fibers, the coconut

reinforced beam gives the high compression strength and modulus of rupture values. Plain

cement concrete beam gives the lowest values of compression strength and modulus of rupture,

while beam reinforced with sugar cane molasses gives intermediate values.

The comparison graph given below demonstrates well the results

Graph4: A comparison graph between three types of beams used in experiment

Where the series show the data of:

Series1: plain cement beam; series2: sugarcane molasses reinf. beam; series3: coconut fiber reinf. Beam

0

100

200

300

400

500

Axi

s Ti

tle

Days

Chart Title

Series1 Series2 Series3

So among the natural fibers, coconut fiber increase strength and durability of the ordinary port

land cement.

Recommendation:

From the research it is recommended to use coconut fiber reinforced

beams. The advantages of using coconut fiber is that it increases bond strength between concrete

aggregate. The beam reinforced with coconut fiber gives warning cracks before ultimate failure.

Furthermore coconut fiber reinforced beam show a little bit ductile behavior in failure

mechanism. Also the addition of coconut fiber reduces the high amount of ordinary port land

cement to gain high strength. Use of coconut fiber is a cheaper method and coconut fibers are

easily available. In this way it is also an environmental friendly method of increasing concrete

strength and durability. On the other hand, the addition of chemicals to port land cement is a

costly and unsafe method. The coconut fibers can also be used in steel reinforced beams.

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