“STUDY OF NATURAL FIBERS AS AN ADMIXTURE FOR CONCRETE MIX DESIGN” (CHAPTER 2)

CHAPTER 2: REVIEW OF RELATED LITERATURE 2009-2010

CHAPTER 2

REVIEW OF RELATED LITERATURE

The use of fibers in brittle matrix materials has a long history going back at least 3500

years when sun-baked bricks reinforced with straw were used to build the 57 meter high hill of

Aqar Quf near Baghdad. In more recent times, asbestos fibers have been used to reinforce

cement products for about 100 years, cellulose fibers for at least 50 years, and steels,

polypropylene and glass fibers have been used for the same purpose for the past 30 years. The

main objectives of the modern engineer in attempting to modify the properties of concrete by the

inclusion of fibers are as follows:

To improve the rheology or plastic cracking characteristics o the material in the

fresh state or up to about 6 hours after casting

To improve the tensile and flexural strength

To improve the impact strength and toughness

To control cracking and the mode of failure by means of post-cracking ductility

To improve durability

2.1 FOREIGN STUDIES

2.1.1. “Palm oil fiber as additive in concrete” by Magendran Subramani (2007)

This research was carried out to establish the effects of palm oil fiber addition on

workability, density, compressive and flexural strength in the concrete mix design of constant

water-cement ratio. The mixes were prepared with fiber-cement ratio of 0.25% and 0.50% and

the mix design was done based on the DOE Method.

The sizes of the specimen tested were 150mm x 150mm x 150mm cubes for compressive

and 100mm x 100mm x 500mm rectangular beams for flexural strength. Specimens were cured

in water for 28 days before testing them. Workability of palm oil fiber added to concreter mix

decreases with the increase of fiber content in the concrete mix. The results from density test also

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demonstrated that the fiber content increases the density of concrete when 0.25% fiber is added,

but the density decreases when 0.50% fiber is added to the concrete. The study on palm oil fiber

shows that adding palm oil fiber to concrete increases the compressive and flexural strength of

concrete after 28 days. Even though adding fiber contributes to strength increase, but the strength

does not increase with the increasing fiber content (percentage). In other words, the increase in

strength is only upto certain amount of fiber content.

2.1.2. “Ultimate compressive and tensile strength of fiber-reinforced concrete containing

Coconut Fibers” by Labadan (2001)

Labadan (2001), in his study entitled “Ultimate compressive and tensile strength of fiber-

reinforced concrete containing Coconut Fibers” tested a fiber reinforced concrete cylinder with

fiber lengths 3cm, 6cm, and 12cm in different percentages of fiber (0.25%, 0.50%, 1.0%) by

weight of plain concrete prepared in 18 batches. He included that a 0.25% fiber by weight of

plain concrete with a length of 6cm gave a good result in splitting tensile strength but no

significant results on compressive strength. He also concluded that the higher tensile strength

could be obtained by immersing the fibers in a cement solution for four hours before mixing

them with concrete.

According to Santha (1999), coconut fibers are good materials for soil erosion and

sedimentation control especially in environmentally-sensitive agricultural areas. This is due to

the low decomposition rate of coconut fibers. In his study coir rolls were used as a stabilization

of riverbanks. This is an innovative fabric-encapsulated technique in stabilization.

Previous studies and investigation of the use of natural fibers as reinforcement to cement

composites showed positive results. Coconut fibers use as reinforcement to cement composite

board satisfies ASTM specifications.

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2.1.3. “Characteristic of concrete Reinforced with San fibers” by Siddique (1996)

Siddique (1996) presented a paper entitled “Characteristic of concrete Reinforced with

San fibers”. The paper shows the result of an experimental investigation carried out to determine

the physical and mechanical properties of natural San (Crotolaria Juncea) Fibers, and their effect

on compressive strength, splitting tensile strength and flexural strength (modulus of rupture) of

concrete. Concrete mixtures were prepared with three volume fractions of San fibers – 0.25%,

0.50% and 0.75%. Experimental results of the mechanical properties of San fibers reinforced

concrete had been compared with the theoretical model developed by Packtiprapha, et al.

Comparison of theoretical and experimental results showed good agreement and were well

within 10%.

Another published work of Siddique (1997) is the experimental investigation carried out

to study the effect of twines made of San natural fibers used as reinforcement, in place of steel

bars, in concrete beams. Three series of tested beams of dimension 100mm x 100mm x 500mm

were tested with three different percentages of twine (0.7512%, 0.5467%, 0.4100% of the cross

sectional area of the beam). Another series of concrete beams were cast with three percent of

twines along with 0.75% of fibers by volume of concrete, fiber length being 25mm. It is

observed from experimental investigation that twines of natural fibers enhance the load carrying

capacity and ductility and can be used effectively as main reinforcement in concrete beams.

Siddique stated that even though the tests show an encouraging result, further studies are still

required to establish the possibilities of its use in actual practice.

2.1.4. “Contribution of fibers to crack reduction of cement composite during the initial and

final setting period” by Balaguru (1994)

Balaguru (1994), in his paper entitled “Contribution of fibers to crack reduction of

cement composite during the initial and final setting period”, presented the contribution of steel

synthetic and cellulose fibers to the shrinkage-crack reduction potential of cement composites

during the initial and final setting period. The primary variables of the investigation were fiber

type, matrix composition and test methods. Fiber type consisted of steel and non-metallic

(synthetic and cellulose) fibers with length varying from a fraction of an inch to 2.4 inches. For

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steel fibers three fiber length of 1.2, 2.0 and 2.4 inches were investigated at volume contents of

75 and 100 lbs/yd3. The non-metallic fibers were made of cellulose in pulp form (microfiber)

with lengths in the order of a few millimeters and microns. The matrix consisted of cement

mortar with various cement-sand ratios, coarse and light weight aggregates in the test methods,

the primary variables were specimen thickness and plane dimensions of test panels. Results

indicated that both steel and synthetic fibers make a definite contribution to shrinkage crack

reduction during the initial and final setting periods. The microfibers (pulp form) are more

effective in rich cement mortar; whereas, the longer fibers are more effective in lean mortars and

concrete. None of the test methods available in the published literature are suitable for

standardization in the present form. The primary drawbacks of the test methods are the attempt to

induce cracks in plain matrices and normal temperature, humidity and wind velocity, and the

possible errors that can occur in the measurement of crack area.

2.1.5. “Natural Fiber as reinforcement” by Robles-Austriaco and Palma (1990)

The use of natural fibers to improve strength and ductility of brittle materials has been

investigated at the Asian Institute of Technology, Bangkok Thailand. The group of Sera, Robles-

Austriaco and Palma (1990) came out with a research entitled “Natural Fiber as reinforcement”.

Their objective is to use the fibers as reinforcement to offer a unique low cost material for

roofing and other structural elements. The mechanical property of wood, bamboo and bamboo

pulp, coir, bagasse and palm fiber cement composites and the durability of jute, ramie, sisal and

coir fiber cement composites with pozzolanas were investigated. The mechanical properties of

straw-clay composites were also studied for use in grain storage silos. Results the investigation

showed that the natural fiber could be use as reinforcement in cement-based composites to

produce low-cost housing elements. Cost comparisons with commercial boards showed that the

natural fibers are not only least in cost, but they offer higher strength, ductility and toughness. It

was also found out that the durability of natural fibers in cement paste could be improved by

partial replacement of cement with pozzolana. The best results in strength were obtained when

49% silica fume is used. It was also concluded that the natural fibers used in non-cement

composites were also applicable.

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2.1.6. “Cement mortar reinforced with natural fibers” by Castro and Naaman (1981)

The relatively high cost of man made fibers and wire meshes used in fiber reinforced

concrete and ferrocement, combined with a reduction in the usage of asbestos fibers prompted

Castro and Naaman (1981) to evaluate natural fibers of the Agave family that are widely

available in Mexico. In their published paper entitled “Cement mortar reinforced with natural

fibers”, they used two types of fibers of the Agave family – the Lechuguilla and Maguey

Pulquero which were bought in the market place of Mexico city and were sold in bulk. Four

specimens of 12.5mm x 75mm x 300mm dimensions were prepared, mixing the components

manually and cured After 28 days, the flexural strength was tested and the result was very

encouraging. They concluded that natural fibers of the Agave family have significant mechanical

properties that made them eligible as potential reinforcement of cementitious matrices. Likewise,

it was concluded that length of fibers of up to 75mm and volume fractions of up 11 percent can

be mixed with a Portland cement matrix and that the elasto-plastic behavior in flexure and

multiple matrix cracking were achieved for volume fraction of fibers above 7 percent.

It was also suggested that further systematic research should be encouraged to discover

other behavior of natural fibers that affect the strength of the composite.

2.2 FOREIGN LITERATURE

2.2.1 Naturally occurring fibers

The oldest form of fiber-reinforced composites was made with naturally occurring fibers

such as straw and horse hair. Modern technology has made it possible to extract fibers

economically from various plants, such as jute and bamboo, to be used in cement composites. A

unique aspect of these fibers is the low amount of energy required to extract these fibers. The

primary problem with the use of these fibers is their tendency to disintegrate in an alkaline

environment. Efforts are being made to improve the durability of these fibers in concrete by

using admixtures to make the concrete less alkaline and by subjecting the fibers to special

treatment.

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2.2.2 Coconut coir fibers

The coconut palm (Cocos nucifera L.) belongs to the family Palmae, an important

member of the monocotyledons. It is tall and stately palm measuring about 15 to 30 meters when

fully mature. It has a tall, stout, somewhat flexible trunk, rising from a swollen base surrounded

by a mass of roots.

Table 2.1: Properties of Coconut Coir

Morphological Properties

Low Median High

Fiber length (mm) 1.0800 1.2000 1.3200

Fiber diameter (mm) 0.0308 0.0352 0.0395

Lumen width (mm) 0.0172 0.0213 0.0254

Cell wall thickness (mm) 0.0067 0.0068 0.0070

Runkel ratio value 0.5500 0.6600 0.7800

Physical Properties

Tensile strength (kg/g.m) 7.70

Elongation (%) 10.62

Chemical Properties

Low Median High

Ash (%) 1.54 2.24 5.40

Solubilities in:

1% NaOH (%) 25.10 25.30 25.50

Alcohol-Benzene (%) 1.70 2.50 10.56

Hot water (%) 2.40 5.15 10.63

Lignin (%) 23.20 40.30 45.84

Holocellulose (%) 49.81 55.55 62.00

Alpha cellulose (%) 32.86 43.44 57.99

Hemi cellulose (%) 0.10 0.25 0.50 * These result was given by FIDA

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2.2.3 Sugarcane baggase fibers

Sugarcane baggase is the fibrous material left after the extraction of juice from sugarcane.

In most instances, baggase has about 50 percent fiber content. The physical properties of the

fibers depend on the variety of sugarcane, its maturity and the efficiency of the milling plant

Table 2.2: Properties of Sugarcane


Low Median High

Fiber length (mm) 0.8 1.7 2.8

Fiber width (mm) 10 22 34

Lumen width (mm) - - -

Cell wall thickness (mm) - - -

Runkel ratio value - - -

Physical Properties

Tensile strength (kg/g.m) -

Elongation (%) -

Chemical Properties

Low Median High

Ash (%) 1.5 2.2 5

Solubilities in:

1% NaOH (%) - - -

Alcohol-Benzene (%) - - -

Hot water (%) - - -

Lignin (%) 19 21 24

Holocellulose (%) 32 40 48

silica 0.7 2.1 3.5

Pentosan 27 29 32 * These result was given by FIDA

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2.2.4 Pineapple fibers

Pineapple plant (Ananas comosus L.) is a member of the family Bromeleaceae. It can be

planted using ratoon, sucker or slip. It consists of a rosette of stiff succulent leaves on massive

upright stem. The leaves are about 3 to 5 feet long and 1 to 2 inches wide tapering to a point,

generally thin and with or without marginal prickles depending on the variety. The fruit which is

an enlarge aggregate of fruitlets is conical and produce a crown at the top with eyes or fruitlets

arranged all over in rectangular fashion. It is edible, juicy, fleshly and yellowish when ripe.

Table 2.3: Properties of Pineapple Fiber


Fiber length (mm) 4.0700

Fiber diameter (mm) 0.0080

Lumen width (mm) 0.0030

Cell wall thickness (mm) 0.0025

Runkel ratio value 1.6700

Physical Properties

Low Median High

Tensile strength (kg/g.m) 22.40 25.73 34.52

Elongation (%) 1.05 1.07 1.88

Fineness (g/1000m) 3.96 5.63 9.90

Chemical Properties:

Chemical Properties Low Median High

Moisture 8.64 9.53 11.91

Ash (%) 0.32 0.86 2.29

Solubilities in:

Alcohol-Benzene (%) 1.01 2.10 3.02

Lignin (%) 0.93 4.60 12.70

Holocellulose (%) 75.23 86.36 92.43

Alpha cellulose (%) 57.86 79.36 87.36* These result was given by FIDA

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2.2.5 Abaca fibers

Abaca is a relative of the banana plant that grows in hot, humid climates. One of the main

producers of abaca is the Philippines, which is why the plant has been mistakenly called Manila

hemp. Unlike banana plants, however, which are valued for their fruit, abaca’s primary benefit is

in its long leaf sheaths, which grow to be 12 to 20 feet high. All parts of the stalk—from the

outer dark layer to the inner most layers—can be extracted, stripped and processed.

Abaca is amazingly strong, long, light and elastic fiber that outperforms hemp, sisal,

cotton, and synthetic fibers.

Table 2.4: Properties of abaca


Low Median High

Fiber length (mm) 2 6 12

Fiber width (mm) 16 24 32

Chemical Properties

Low Median High

Ash (%) 3 - -

Solubilities in:

1% NaOH (%) - - -

Alcohol-Benzene (%) - - -

Hot water (%) - - -

Lignin (%) 7 9

Holocellulose (%) 56 60 63

Silica - - -

Pentosan 15 16 17 * These result was given by FIDA

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“STUDY OF NATURAL FIBERS AS AN ADMIXTURE FOR CONCRETE MIX DESIGN” (CHAPTER 2)

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