PROJECT REPORT

ENHANCING THE

PROPERTIES OF CONCRETE

BY ADDING HAIR FIBER

A report submitted in partial fulfillment of the

requirements for the award of the certificate of

Diploma

in

CIVIL ENGINEERING

Submitted By

Rohit chaudhary (143000247)

Santosh fozdar (143000254)

Satish chand (143000255)

Shekhar yadav (143000266)

Under the supervision of

Mr. Krishan murari sharma

Department of Civil Engineering

GLA University Polytechnic

May-June, 2017

ENHANCING THE

PROPERTIES OF CONCRETE

BY ADDING HAIR FIBER

A report submitted in partial fulfillment of the

requirements for the award of the certificate of

Diploma

in

CIVIL ENGINEERING

Submitted By

Rohit chaudhary (143000247)

Santosh fozdar (143000254)

Satish chand (143000255)

Shekhar yadav (143000266)

Under the supervision of

Mr. Krishan murari sharma

Department of Civil Engineering

University Polytechnic

May-June, 2017

DECLARATION

I hereby declare that the work which is presented in Diploma Sixth semester.

“Enhancing the properties of concrete by adding hair fiber ” in partial

fulfillment of the requirements for the award of the Diploma in Civil Engineering

and submitted to the Department of Civil Engineering of GLA University

Polytechnic, Mathura is an authentic record of my own work carried under the

supervision of Mr. krishan murari sharma

(Lecturer in GLA University ).

Name of the candidates:

Rohit chaudhary (143000247)

Santosh Fozdar (143000254)

Satish Chand (143000255)

Shekhar Yadav (143000266)

CERTIFICATE

Certified that this project report “ENHANCING THE

PROPERTIES OF CONCRETE BY ADDING HAIR FIBER” is the

bonafide work of “Rohit, Santosh, Satish, Shekhar” who carried

out the project work under my supervision.

Signature of Project Guide Mr. Krishna Murari Sharma Lecturer GLA University Polytechnic

ACKNOWLEDGEMENT

It gives me a great sense of pleasure to present the progress report work,

undertaken during Diploma Six Semester. I owe special debt of gratitude to Mr.

(Mr. Krishan murari sharma), Department of Civil Engineering, GLA University

Polytechnic, Mathura for their constant support and guidance throughout the

course of my work. His sincerity, thoroughness and perseverance have been a

constant source of inspiration for me. It is only their cognizant efforts that my

endeavors have seen light of the day.

We also take the opportunity to acknowledge the contribution of Dr. Diwakar

Bhardwaj and Dr. Vikas Sharma, Principals University Polytechnic, GLA University,

Mathura for their full support.

I also do not like to miss the opportunity to acknowledge the contribution of Mr.

Sanjay Agarwal, Mr.Pravesh Tiwari, Mr.Prashant sharma, Mr. Mayankesher

Singh and all faculty members of the department for their kind assistance and co-

operation during the development of my report. Last but not the least, I

acknowledge my friends for their contribution in the completion of the project.

Sign:

Rohit chaudhary (143000247)

Santosh Fozdar (143000254)

Satish Chand (143000255)

Shekhar Yadav (143000266)

DATE:

Abstract

This project is intended to analyze the Performance of Hair Reinforced

Concrete. Fibre reinforced concrete can offer a convenient, practical and

economical method for overcoming micro-cracks and similar type of

deficiencies. Since concrete is weak in tension hence some measures must

be adopted to overcome this deficiency. Human hair is strong in tension;

hence it can be used as a fibre reinforcement material. Hair Fibre (HF) an

alternate non-degradable matter is available in abundance and at a very

cheap cost. It also creates environmental problem for its decompositions.

This particular project has been undertaken to study the effect of human

hair on plain cement concrete on the basis of its compressive strength,

flexural strength, and rheological parameter. Experiments were conducted

on concrete beams and cubes with various percentages of human hair fibre

i.e. 0%, 0.5%, 1%, 1.5% by weight of cement. For each combination of

proportions of concrete one beam and three cubes are tested for their

mechanical properties. By testing of cubes and beams we found that there is

an increment in the various properties and strength of concrete by the

addition of human hair as fibre reinforcement.

Objective

Develop suitable mix design.

Develop characterization tests for the fiber.

Demonstrate the use of steel fiber from use of waste natural fiber.

For checking the effect on properties and strength of concrete by using hair fiber as

reinforcement.

Introduction

Definition & History of concrete is a material used in building construction, consisting of a

hard, chemically inert particulate substance, known as an aggregate (usually made from

different types of sand and gravel), that is bonded together by cement and water. In 1756,

British engineer, John Smeaton made the first modern concrete (hydraulic cement) by adding

pebbles as a coarse aggregate and mixing powered brick into the cement. In 1824, English

inventor, Joseph Aspdin invented Portland cement, which has remained the dominant cement

used in concrete production. Joseph Aspdin created the first true artificial cement by burning

ground limestone and clay together. The burning process changed the chemical properties of

the materials and Joseph Aspdin created stronger cement than what using plain crushed

limestone would produce.

Biological fibers have been already used some 3000 years ago in composite systems in the

ancient Egypt, where straw and clay were mixed together to build the walls. In the last few years,

biological fibers have become an attractive reinforcement for polymeric composites from

economical and ecological point of view. There is an increase in the environmental awareness in

the world which has aroused an interest in the research and the development of biodegradable

materials. Biological/Natural fibers can be obtained from natural resources such as plants,

animals or minerals .

With the increase of global energy crisis and ecology risk, the unique advantages of biological

fibers such as its abundance quantity, non-toxic, non-irritation of the skin, eyes, or respiratory

system, noncorrosive property, biological fiber reinforced polymer composites have attracted

much interest owing to their potential of serving as alternatives reinforcement to the synthetic

ones [2]. The lower weight and higher volume of the biological fibers as compared to the

synthetic fibers improve the fuel efficiency and reduced emission in auto applications .

Hair is a protein filament that grows from follicles found in the dermis or skin. It is one of the

defining characteristics of mammals. The human body, apart from areas of glabrous skin, is

covered in follicles which produce thick terminal and fine vellus hair. Most common interest in

hair is focused on hair growth, hair types and hair care, but hair is also an important biomaterial

primarily composed of protein, notably keratin. Keratins are proteins, long chains (polymers) of

amino acids. In terms of raw elements, on an average, hair is composed of 50.65% carbon,

20.85% oxygen, 17.14% nitrogen, 6.36% hydrogen, and 5.0% sulphur. Amino acid present in

hair contain cytosine, serine, glutamine, threonine, glycine, leucine, valine and arginine [5].

The word “hair” usually refers to two distinct structures:

The part beneath the skin called the hair follicle or when pulled from the skin, called the bulb.

This organ is located in the dermis and maintains stem cells, which not only re-grow the hair

after it falls out, but also are recruited to regrow skin after a wound.

The shaft, which is the hard filamentous part that extends above the skin surface.

The cross section of human hair shaft may be divided roughly into three zones:

The cuticle, which consists of several layers of flat, thin cells laid out overlapping one another as

roof shingles.

The cortex, which contains the keratin bundles in cell structures that remain roughly rod like.

Fiber

Fiber Reinforced Concrete can be defined as a composite material consisting of mixtures of

cement, mortar or concrete and discontinuous, discrete, uniformly dispersed suitable fibers. Fiber

reinforced concrete are of different types and properties with many advantages. Continuous

meshes, woven fabrics and long wires or rods are not considered to be discrete fibers. Fiber is a

small piece of reinforcing material possessing certain characteristics properties. They can be

circular or flat. The fiber is often described by a convenient parameter called “aspect ratio”. The

aspect ratio of the fiber is the ratio of its length to its diameter. Typical aspect ratio ranges from

30 to 150.

Advantages of fibre reinforced concrete

(1) FRC is used in civil structures where corrosion is to be avoided at the maximum.

(2) FRC is better suited to minimize cavitations erosion damage in structures where high

velocity flows are encountered.

(3) A substantial weight saving can be realized using relatively thin FRC sections having the

equivalent strength of thicker plain concrete sections.

(4) When used in ridges it helps to avoid catastrophic failures. In quake prone areas the

use of fibre reinforced concrete would certainly minimize the human casualties.

(5) Fibre reduces internal forces by locking microscopic cracks from forming within the

concrete.

(6) Studies have been proven that fibre reinforced concrete is found to improve the following

mechanical properties of ordinary concrete: Compressive Strength, Modulus of Elasticity and

flexural strength, Toughness, Splitting Tensile Strength, Fatigue Strength, and Impact

Resistance..

Disadvantages

The fibres have to be uniformly mixed and spread throughout the concrete mix. At times, this is

found to be a difficult process and time consuming. If this limitation has been overcome by new

and effective methods of fabrication, fibre reinforced concrete is found to be more adaptable for

common concreting works.

Why Fibres are used in Concrete?

Fibres are usually used in concrete for the following reasons:

i. To control cracking due to both plastic shrinkage and drying shrinkage.

ii. They also reduce the permeability of concrete and thus reduce bleeding of water.

iii. Some types of fibres also produce greater impact, abrasion and shatter resistance in

concrete.

iv. The fineness of the fibres allows them to reinforce the mortar fraction of the concrete,

delaying crack formation and propagation. This fineness also inhibits bleeding in the

concrete, thereby reducing permeability and improving the surface characteristics of the

hardened surface.

Main Properties of Fibre in FRC:

Type of fibres used,Volume percent of fibre (vf =0.1 to 3%), Aspect ratio (the length of a fibre

divided by its diameter), Orientation and distribution of the fibres in the matrix, It prevents

spalling of concrete, Shape, dimension and length of fibre is important,Strength of the fibre.

Effect of Fibers in Concrete

Fibers are usually used in concrete to control plastic shrinkage cracking and drying shrinkage

cracking. They also lower the permeability of concrete and thus reduce bleeding of water. Some

types of fibers produce greater impact, abrasion and shatter resistance in concrete. Generally

fibers do not increase the flexural strength of concrete, so it can not replace moment resisting or

structural steel reinforcement. Some fibers reduce the strength of concrete. Some recent research

indicated that using fibers in concrete has limited effect on the impact resistance of concrete

materials. This finding is very important since traditionally people think the ductility increases

when concrete reinforced with fibers. The results also pointed out that the micro fibers is better

in impact resistance compared with the longer fibers.

Necessity of Fiber Reinforced Concrete:

1. It increases the tensile strength of the concrete.

2. It reduce the air voids and water voids the inherent porosity of gel.

3. It increases the durability of the concrete.

4. Fibers such as graphite and glass have excellent resistance to creep, while the same is not

true for most resins. Therefore, the orientation and volume of fibers have a significant

influence on the creep performance of rebars/tendons.

5. Reinforced concrete itself is a composite material, where the

reinforcement acts as the strengthening fiber and the concrete as the

matrix. It is therefore imperative that the behavior under thermal stresses

for the two materials be similar so that the differential deformations of

concrete and the reinforcement are minimized.

6. It has been recognized that the addition of small, closely spaced and uniformly dispersed

fibers to concrete would act as crack arrester and would substantially improve its static

and dynamic properties.

Factors Affecting Properties of Fiber Reinforced Concrete

Fiber reinforced concrete is the composite material containing fibers in the cement matrix in an

orderly manner or randomly distributed manner. Its properties would obviously, depends upon

the efficient transfer of stress between matrix and the fibers. The factors are briefly discussed

below:

1. Relative Fiber Matrix Stiffness

2. Volume of Fibers

3. Aspect Ratio of the Fiber

4. Orientation of Fibers

5. Workability and Compaction of Concrete

6. Size of Coarse Aggregate

7. Mixing

Fiber reinforced concrete

Fiber reinforced concrete (FRC) is concrete containing fibrous material which increases its

structural integrity. It contains short discrete fibers that are uniformly distributed and randomly

oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers. Within these

different fibers that character of fiber reinforced concrete changes with varying concretes, fiber

materials, geometries, distribution, orientation and densities.

Different Types of Fiber Reinforced Concrete

Following are the different type of fibers generally used in the construction industries.

Steel Fiber Reinforced Concrete

Polypropylene Fiber Reinforced (PFR) cement mortar & concrete

GFRC Glass Fiber Reinforced Concrete

Asbestos Fibers

Carbon Fibers

Organic Fibers

Organic Fibers/Natural fiber:

Organic fiber such as polypropylene or natural fiber may be chemically more inert than either

steel or glass fibers. They are also cheaper, especially if natural. A large volume of vegetable

fiber may be used to obtain a multiple cracking composite. The problem of mixing and uniform

dispersion may be solved by adding a super plasticizer. We prefer hair fiber.

Why Hair as a Fibre?

Hair is used as a fibre reinforcing material in concrete for the following reasons: i. It has a high

tensile strength which is equal to that of a copper wire with similar diameter. ii. Hair, a non-

degradable matter is creating an environmental problem so its use as a fibre reinforcing

material can minimize the problem. iii. It is also available in abundance and at a very low cost.

iv. It reinforces the mortar and prevents it from spalling.

Treatment of hair fibre

The hair needed for the preparation of concrete cubes was collected from salons and beauty

parlours. It needs treatment before to be added in the concrete specimens. It is carried out as in

the following steps:

• Separating hair from other waste: Depending on the source, the collected hair may contain

wastes. This has to be removed.

• Washing: After sorting, the hair is washed with acetone to remove impurities.

• Drying: The hair is then dried under sun or in oven. After drying, the hair can be stored without

any concern for decay or odor.

• Sorting: The hair is then sorted according to length, color, and quality. The hair fibres are

checked at random for its length and diameter.

Hair as Fibre in Fibre Reinforced Concrete

Hair is used as a fibre because it has a high elasticity which is equivalent to that of a copper wire

with comparable width. Hair, a non-degradable matter is making an ecological issue so its

utilization as a fiber fortifying material can minimize the issue. It is additionally accessible in

wealth and with ease. It fortifies the mortar and keeps it from spalling for this project we have

used hair with fibre length between 15 mm to 60mm.

Mechanical properties of human hair fiber

Ganiron investigated the effects of human hair additives in compressive strength of asphalt

cement mixture and concluded that addition of hair to the asphalt cement mixture greatly

improves its capability to bear more loads applied to it. Choudhry and Pandey studied the

mechanical behaviour of polypropylene matrix and human hair fiber and founded that composite

with 3-5 wt.% of human hair fiber shows higher flexural strength, flexural modulus and Izod

impact strength than non-reinforced polymer but at 10-15 wt.% it lowers the flexural strength,

flexural modulus and Izod impact strength as compared to the non-reinforced polymer.

Fueghelman examined the mechanical properties and structure of alpha-keratin fibers such as

wool, human hair and related fibers and concluded that the human hair possesses the highest

tensile strength amongst the compared fibers. He further unlocked the exceptional properties of

human hair such as its unique chemical composition, slow degradation rate, high tensile strength,

thermal insulation, elastic recovery, scaly surface, and unique interactions with water and oils

that has led to many diverse uses of the corresponding fiber.

Thompson manufactured a hair based composite material by manipulating a plurality of cut

lengths of hair to form a web or mat of hair and combining with a structural additive to form the

required composite material. Jain and Kothari studied on human hair fiber reinforced concrete

and concluded that there is tremendous increment in properties of concrete according to the

percentages of hairs by weight of in concrete. The addition of human hairs to the concrete

improves various properties of concrete like tensile strength, compressive strength, binding

properties, micro cracking control and also increases spalling resistance. Barone has also shown

that the human hair fiber is a non-homogeneous complex material made of keratin fibers oriented

along the longitudinal axis which offer anisotropic mechanical properties. According to them, it

is possible to measure the mechanical properties of hairs with the classical tests, but most often,

these tests are destructive and make hard to measure the influence of some external factors or

treatments on the behaviour of a same hair fiber. They utilized vibrations induced by a non-

contact impact as a representative response of the mechanical behaviour of hair. The

characteristics of the vibratory response allow measuring the variation in the mechanical

properties and the instantaneous effect of an external factor on the properties of a same sample.

First, load relaxation tests have been performed on hair samples after moisturisation and for

different times of an air-drying process in order to characterize the change in the visco-elastic

behaviour of hair during the water desorption. The vibratory response has then been correlated to

the mechanical properties of the hair fiber.

Barone and Ahmad prepared composites taking human hair as the fiber and polymers as the

matrix and firmed that the human hair is an emerging engineering composite fiber. They

collectively wrapped up with the conclusion that the tensile and flexural properties decrease

when the fiber loading percentage increases. Utilizing whole fiber not only provided good

properties but will also eliminate the need for processing the fiber leading to lower costs and

superior characteristics. The tensile properties can be enhanced with the increasing percentage of

the human hair fiber and also with different matrix. Another way to enhance the composite

properties is to determine an effective treatment to eliminate lack of adhesion between matrix

and fiber, which was approved by Ganiron and Belani et al. who took concrete and fly ash

respectively, as the matrix. Due to the above discussed incomparable mechanical properties of

human hairs, which are in relative abundance in nature and are nondegradable.

Chemical experimentations on human hair fiber

Hair is a proteinaceous fiber with a strongly hierarchical organization of subunits, from the α-

keratin chains, via intermediate filaments to the fiber, as suggested by Popescu and Hocker.

Thomas et al.determined that the hair contains a high amount of sulphur because α-amino acid

cysteine (HO2CCH(NH2)CH2SH) is a key component of the keratin proteins in hair fiber,

focused on the comparative study of chemical composition of the human hair on different races

of different continents. Hu et al. studied on protein based composite biomaterials which can be

formed into a wide range of biomaterials with tunable properties, including control of cell

responses. They provided new biomaterials which is an important need in the field of biomedical

science, with direct relevance to tissue regeneration, nano-medicine and disease treatments.

Volkin and Klibanov identified and characterized the processes leading to destruction of cysteine

residues. They compared proteins from different species, including those of thermophilic

bacteria living near the boiling point of water.

Hernandez and Santos studied on keratin which is a fiber, found in hair and feathers. Keratin

fiber has a hierarchical structure with a highly ordered conformation, is by itself a bio-composite,

product of a large evolution of animal species. Through their research it was concluded that the

keratin fibers from chicken feathers shows an eco-friendly material which can be applied in the

development of green composites. Hernandez et al. have previously developed a matrix solid

phase dispersion (MSPD) method and it proved to offer quantitative results when isolating

cocaine, benzoylecgonine (BZE), codeine, morphine and 6-monoacethylmorphine (6-MAM)

from human hair samples which further determined the chemical composition of human hair.

Overall they scrutinized the dynamical, mechanical and chemical analysis of polymeric

composites reinforced with keratin biological fiber from human hair composites and founded the

capability of human hair as a proficient fiber in the industry.

Renju et al.founded an innovative chemical technique of improving the soil fertility by using

human hair fibers. Robbins described the hair as a protein filament that grows from follicles

found in the dermis, or skin. Most common interest in hair is focused on hair growth, hair types

and hair care, but hair is also an important biomaterial primarily composed of protein, notably

keratin.

Preparation of specimen:

It is the most common test conducted on hardened concrete as it is an easy test to perform and

also most of the desirablecharacteristic properties of concrete are qualitatively related to

compressive strength. The compression test is carried out on specimens cubical in shape as

shown in figure of the size 150 × 150 × 150 mm. The test is carried out in the following steps:

First of all the mould preferably of cast iron, is used to prepare the specimen of size 150 × 150 ×

150 mm. During the placing of concrete in the moulds it is compacted with the tamping bar with

not less than 25 strokes per layer. Then these moulds are placed on the vibrating table and are

compacted until the specified condition is attained. After 24 hours the specimens are removed

from the moulds and immediately submerged in clean fresh water. After 28 days the specimens

are tested under the load in a compression testing machine.

MATERIALS USED:

Cement: This is the most common binding material used in concrete production. The cement

used in this study is Ultra-tech OPC of 53 grade confirming to IS: 12269-1987.Physical

properties of cement show in table no.1 which is given below.

Fineregate: Locally available fresh river sand, free from organic matter, was used. The result of

sieve analysis confirms-ΙI (according to IS: 383-1970)

Coarse aggregate: For this study the locally available good quality coarse aggregate is used.

The size of coarse aggregate varies from 10 mm to 20 mm, means the material passed from

20mm IS sieve but retained in 10mm IS sieve.

Properties of concrete:

Properties of concrete are influenced by many factors mainly due to mix proportion of cement,

sand, aggregates and water. Ratio of these materials control the various concrete properties

which are discussed below. Concrete has relatively high compressive strength, but significantly

lower tensile strength, and as such is usually reinforced with materials that are strong in tension

(often steel). The elasticity of concrete is relatively constant at low stress levels but starts

decreasing at higher stress levels as matrix cracking develops. Concrete has a very low

coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will

crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration

forces is prone to creep.

Tests can be made to ensure the properties of concrete correspond to specifications for the

application. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150

lb/cu ft).[1] As a result,[further explanation needed] without compensating, concrete would

almost always fail from tensile stresses – even when loaded in compression. The practical

implication of this is that concrete elements subjected to tensile stresses must be reinforced with

materials that are strong in tension.

Reinforced concrete is the most common form of concrete. The reinforcement is often steel,

rebar (mesh, spiral, bars and other forms). Structural fibers of various materials are available.

Concrete can also be prestressed (reducing tensile stress) using internal steel cables (tendons),

allowing for beams or slabs with a longer span than is practical with reinforced concrete alone.

Inspection of existing concrete structures can be non-destructive if carried out with equipment

such as a Schmidt hammer, which is sometimes used to estimate relative concrete strengths in

the field.

The ultimate strength of concrete is influenced by the water-cementitious ratio (w/cm), the

design constituents, and the mixing, placement and curing methods employed. All things being

equal, concrete with a lower water-cement (cementitious) ratio makes a stronger concrete than

that with a higher ratio. The total quantity of cementitious materials (portland cement, slag

cement, pozzolans) can affect strength, water demand, shrinkage, abrasion resistance and

density. All concrete will crack independent of whether or not it has sufficient compressive

strength. In fact, high Portland cement content mixtures can actually crack more readily due to

increased hydration rate. As concrete transforms from its plastic state, hydrating to a solid, the

material undergoes shrinkage. Plastic shrinkage cracks can occur soon after placement but if the

evaporation rate is high they often can actually occur during finishing operations, for example in

hot weather or a breezy day. In very high-strength concrete mixtures (greater than 70 MPa) the

crushing strength of the aggregate can be a limiting factor to the ultimate compressive strength.

In lean concretes (with a high water-cement ratio) the crushing strength of the aggregates is not

so significant. The internal forces in common shapes of structure, such as arches, vaults, columns

and walls are predominantly compressive forces, with floors and pavements subjected to tensile

forces. Compressive strength is widely used for specification requirement and quality control of

concrete. Engineers know their target tensile (flexural) requirements and will express these in

terms of compressive strength.

Elasticity

The modulus of elasticity of concrete is a function of the modulus of elasticity of the aggregates

and the cement matrix and their relative proportions. The modulus of elasticity of concrete is

relatively constant at low stress levels but starts decreasing at higher stress levels as matrix

cracking develops. The elastic modulus of the hardened paste may be in the order of 10-30 GPa

and aggregates about 45 to 85 GPa. The concrete composite is then in the range of 30 to 50 GPa.

Expansion and shrinkage

Concrete has a very low coefficient of thermal expansion. However, if no provision is made for

expansion, very large forces can be created, causing cracks in parts of the structure not capable

of withstanding the force or the repeated cycles of expansion and contraction. The coefficient of

thermal expansion of Portland cement concrete is 0.000008 to 0.000012 (per degree Celsius) (8

to 12 microstrains/°C)(8-12 1/MK).

Thermal Conductivity

Concrete has moderate thermal conductivity, much lower than metals, but significantly higher

than other building materials such as wood, and is a poor insulator.

A layer of concrete is frequently used for 'fireproofing' of steel structures. However, the term

fireproof is inappropriate, for high temperature fires can be hot enough to induce chemical

changes in concrete, which in the extreme can cause considerable structural damage to the

concrete.

Cracking

As concrete matures it continues to shrink, due to the ongoing reaction taking place in the

material, although the rate of shrinkage falls relatively quickly and keeps reducing over time (for

all practical purposes concrete is usually considered to not shrink due to hydration any further

after 30 years). The relative shrinkage and expansion of concrete and brickwork require careful

accommodation when the two forms of construction interface.

All concrete structures will crack to some extent. One of the early designers of reinforced

concrete, Robert Maillart, employed reinforced concrete in a number of arched bridges. His first

bridge was simple, using a large volume of concrete. He then realized that much of the concrete

was very cracked, and could not be a part of the structure under compressive loads, yet the

structure clearly worked. His later designs simply removed the cracked areas, leaving slender,

beautiful concrete arches. The Salginatobel Bridge is an example of this.

Concrete cracks due to tensile stress induced by shrinkage or stresses occurring during setting or

use. Various means are used to overcome this. Fiber reinforced concrete uses fine fibers

distributed throughout the mix or larger metal or other reinforcement elements to limit the size

and extent of cracks. In many large structures joints or concealed saw-cuts are placed in the

concrete as it sets to make the inevitable cracks occur where they can be managed and out of

sight. Water tanks and highways are examples of structures requiring crack control.

Shrinkage cracking

Shrinkage cracks occur when concrete members undergo restrained volumetric changes

(shrinkage) as a result of either drying, autogenous shrinkage or thermal effects. Restraint is

provided either externally (i.e. supports, walls, and other boundary conditions) or internally

(differential drying shrinkage, reinforcement). Once tensile strength of the concrete is exceeded,

a crack will develop. The number and width of shrinkage cracks that develop are influenced by

the amount of shrinkage that occurs, the amount of restraint present and the amount and spacing

of reinforcement provided.These are minor indications and have no real structural impact on the

concrete member.Plastic-shrinkage cracks are immediately apparent, visible within 0 to 2 days of

placement, while drying-shrinkage cracks develop over time. Autogenous shrinkage also occurs

when the concrete is quite young and results from the volume reduction resulting from the

chemical reaction of the Portland cement.

Tension cracking

Concrete members may be put into tension by applied loads. This is most common in concrete

beams where a transversely applied load will put one surface into compression and the opposite

surface into tension due to induced bending. The portion of the beam that is in tension may

crack. The size and length of cracks is dependent on the magnitude of the bending moment and

the design of the reinforcing in the beam at the point under consideration. Reinforced concrete

beams are designed to crack in tension rather than in compression. This is achieved by providing

reinforcing steel which yields before failure of the concrete in compression occurs and allowing

remediation, repair, or if necessary, evacuation of an unsafe area.

Creep

Creep is the permanent movement or deformation of a material in order to relieve stresses within

the material. Concrete that is subjected to long-duration forces is prone to creep. Short-duration

forces (such as wind or earthquakes) do not cause creep. Creep can sometimes reduce the amount

of cracking that occurs in a concrete structure or element, but it also must be controlled. The

amount of primary and secondary reinforcing in concrete structures contributes to a reduction in

the amount of shrinkage, creep and cracking.

Water retention

cement concrete holds water. However, some types of concrete (like Pervious concrete allow

water to pass, hereby being perfect alternatives to Macadam roads, as they do not need to be

fitted with storm drains.

Properties of Concrete are:

Grades (M25)

Compressive strength

Characteristic Strength

Tensile strength

Durability

Creep

Shrinkage

Unit weight

Modular Ratio

Poisson’s ratio

Grades of concrete:

Concrete is known by its grade which is designated as M25 etc. in which letter M refers to

concrete mix and number 15, 20 denotes the specified compressive strength (fck) of 150mm

cube at 28 days, expressed in N/mm2. Thus, concrete is known by its compressive strength. M20

and M25 are the most common grades of concrete, and higher grades of concrete should be used

for severe, very severe and extreme environments.

Data Required for Concrete Mix Design

(i) Concrete Mix Design Stipulation

(a) Characteristic compressive strength required in the field at 28 days grade designation — M

25

(b) Nominal maximum size of aggregate — 20 mm

(c) Shape of CA — Angular

(d) Degree of workability required at site — 50-75 mm (slump)

(e) Degree of quality control available at site — As per IS:456

(f) Type of exposure the structure will be subjected to (as defined in IS: 456) — Mild

(g) Type of cement: PSC conforming IS:455

(h) Method of concrete placing: pump able concrete

(ii) Test data of material (to be determined in the laboratory)

(a) Specific gravity of cement — 3.15

(b) Specific gravity of FA — 2.64

(c) Specific gravity of CA — 2.84

(d) Aggregate are assumed to be in saturated surface dry condition.

(e) Fine aggregates confirm to Zone II of IS – 383

Procedure for Concrete Mix Design of M25 Grade Concrete

Step 1 — Determination Of Target Strength

Himsworth constant for 5% risk factor is 1.65. In this case standard deviation is taken from

IS:456 against M 20 is 4.0.

ftargetftarget = fck + 1.65 x S

= 25 + 1.65 x 4.0 = 31.6 N/mm2

Where,

S = standard deviation in N/mm2 = 4 (as per table -1 of IS 10262- 2009)

Step 2 — Selection of water / cement ratio:-

Maximum water-cement ratio for Mild exposure condition = 0.55

Based on experience, adopt water-cement ratio as 0.5.

0.5<0.55, hence OK.

Step 3 — Selection of Water Content Table 2 of IS 10262- 2009,Maximum water content = 186

Kg (for Nominal maximum size of aggregate — 20 mm)

Step 4 — Selection of Cement Content

Water-cement ratio = 0.5

Corrected water content = 191.6 kg /m3

Cement content =

From Table 5 of IS 456,

Minimum cement Content for mild exposure condition = 300 kg/m3

383.2 kg/m3 > 300 kg/m3, hence, OK.

This value is to be checked for durability requirement from IS: 456.

In the present example against mild exposure and for the case of reinforced concrete the

minimum cement content is 300 kg/m3 which is less than 383.2 kg/m3. Hence cement content

adopted = 383.2 kg/m3.

AsAs per clause 8.2.4.2 of IS: 456

Maximum cement content = 450 kg/cm3.

Estimation

MIX PROPORSION M25

Quantity of cement (kg

6.68

Quantity of sand (kg)

6.68

Quantity of coarse aggregate (kg

13.36

Water cement ratio

0.55

Quantity of water (l

3.67

Estimation of the mix ingredients

a) Volume of concrete = 1 m3

b) Volume of cement = (Mass of cement / Specific gravity of cement) x (1/100)

= (383.2/3.15) x (1/1000) = 0.122 m3

c) Volume of water = (Mass of water / Specific gravity of water) x (1/1000)

= (191.6/1) x (1/1000) = 0.1916 m3

d) Volume of total aggregates = a – (b + c ) = 1 – (0.122 + 0.1916) = 0.6864 m3

e) Mass of coarse aggregates = 0.6864 x 0.558 x 2.84 x 1000 = 1087.75 kg/m3

f) Mass of fine aggregates = 0.6864 x 0.442 x 2.64 x 1000 = 800.94 kg/m3

Concrete Mix proportions for Trial Mix 1

Cement = 383.2 kg/m3

Water = 191.6 kg/m3

Fine aggregates = 800.94 kg/m3

Coarse aggregate = 1087.75 kg/m3

W/c = 0.5

For trial -1 casting of concrete in lab, to check its properties.

It will satisfy durability & economy.

For casting trial -1, mass of ingredients required will be calculated for 4 no’s cube assuming 25%

wastage.

Volume of concrete required for 4 cubes = 4 x (0.153 x1.25) = 0.016878 m3

Cement = (383.2 x 0.016878) kg/m3 = 6.47 kg

Water = (191.6 x 0.016878) kg/m3 =3.23 kg

Coarse aggregate = (1087.75 x 0.016878) kg/m3 =18.36 kg

Fine aggregates = (800.94 x 0.016878) kg/m3 = 13.52 kg

Correction due to absorbing / moist aggregate:-

Since the aggregate is saturated surface dry condition hence no correction is required.

Concrete Trial Mixes:-

Concrete Trial Mix 1:

The mix proportion as calculated in Step 6 forms trial mix1. With this proportion, concrete is

manufactured and tested for fresh concrete properties requirement i.e. workability, bleeding and

finishing qualities.

In this case,

Slump value = 25 mm

Compaction Factor = 0.844

So, from slump test we can say,

Mix is cohesive, workable and had a true slump of about 25 mm and it is free from segregation

and bleeding.

Desired slump = 50-75 mm . So modifications are needed in trial mix 1 to arrive at the desired

workability.

Concrete Trial Mix 2:

To increase the workability from 25 mm to 50-75 mm an increase in water content by +3% is to

be made.

The corrected water content = 191.6 x 1.03 = 197.4 kg.

As mentioned earlier to adjust fresh concrete properties the water cement ratio will not be

changed. Hence

Cement Content = (197.4/0.5) = 394.8 kg/m3

Which also satisfies durability requirement.

Volume of all in aggregate = 1 – [{394.8/(3.15×1000)} + {197.4/(1 x 1000)}] = 0.6773 m3

Mass of coarse aggregate = 0.6773 x 0.558 x 2.84 x 1000 = 1073.33 kg/m3

Mass of fine aggregate = 0.6773 x 0.442 x 2.64 x 1000 = 790.3 kg/m3

Concrete Mix Proportions for Trial Mix 2

Cement = 384.8 kg/m3

Water = 197.4 kg/m3

Fine aggregate =790.3 kg/m3

Coarse aggregate = 1073.33 kg/m3

For casting trial -2, mass of ingredients required will be calculated for 4 no’s cube assuming 25%

wastage.

Volume of concrete required for 4 cubes = 4 x (0.153 x1.25) = 0.016878 m3

Cement = (384.8 x 0.016878) kg/m3 = 6.66 kg

Water = (197.4 x 0.016878) kg/m3 =3.33 kg

Coarse aggregate = (1073.33 x 0.016878) kg/m3 =18.11 kg

Fine aggregates = (790.3 x 0.016878) kg/m3 = 13.34 kg

In this case,

Slump value = 60 mm

Compaction Factor = 0.852

So, from slump test we can say,

Mix is very cohesive, workable and had a true slump of about 60 mm.

It virtually flowed during vibration but did not exhibit any segregation and bleeding.

Desired slump = 50-75 mm

So , it has achieved desired workability by satisfying the requirement of 50-75 mm slump value .

Now , we need to go for trial mix-3 .

Concrete Trial Mix 3:

In case of trial mix 3 water cement ratio is varied by +10% keeping water content constant. In

the present example water cement ratio is raised to 0.55 from 0.5.

An increase of 0.05 in the w/c will entail a reduction in the coarse aggregate fraction by 0.01.

Hence the coarse aggregate as percentage of total aggregate = 0.558 – 0.01 = 0.548

W/c = 0.55

Water content will be kept constant.

Cement content = (197.4/0.55) = 358.9 kg/m3

Hence, volume of all in aggregate

= 1 – [{(358.9/(3.15 x 1000)} + (19)

Water cement Ratio

We add water only to hydrate cement. Aggregates do not require water.

So water cement ratio is defined.

As the strength increase cement content increase, so water also increase.

Both water and cement increase so water cement ratio almost remain

same.

If we add less water…cement remain unhydrated

If we add more water….density decreases and strength decrease.

So.we have to add water to exactly hydrate cement. Amount of cement

changes from place to place due to change in shapes and sizes of

aggregate.

Till M25 grade 0.4 to 0.6 will be sufficient. We have to check till

sufficient workability is attained. It is not fixed with strength.

METHODS OF PROPORTIONING CONCRETE

(1) Arbitrary Method

The general expression for the proportions of cement, sand and coarse aggregate is 1 : n : 2n by

volume.

1 : 1 : 2 and 1 : 1.2 : 2.4 for very high strength.

1 : 1.5 : 3 and 1 : 2 : 4 for normal works.

1 : 3 : 6 and 1 : 4 : 8 for foundations and mass concrete works.

(2) Fineness Modulus Method:

The term fineness modulus is used to indicate an index number which is roughly proportional to

the average size of the particle in the entire quantity of aggregates.

The fineness modulus is obtained by adding the percentage of weight of the material retained on

the following sieve and divided by 100.

The coarser the aggregates, the higher the fineness modulus.

Sieve is adopted for:

All aggregates : 80 mm, 40 mm, 20 mm, 10 mm, and Nos. 480, 240, 120, 60, 30 and 15.

Coarse aggregates : mm, 40 mm, 20 mm, 10 mm, and No. 480.

Fine aggregates : Nos. 480, 240, 120, 60, 30 and 15.

Proportion of the fine aggregate to the combined aggregate by weight

(3) Minimum Void Method (Does not give satisfactory result)

The quantity of sand used should be such that it completely fills the voids of coarse aggregate.

Similarly, the quantity of cement used shown such that it fills the voids of sand, so that a dense

mix the minimum voids is obtained.

In actual practice, the quantity of fine aggregate used in the mix is about 10% more than the

voids in the coarse aggregate and the quantity of cement is kept as about 15% more than the

voids in the fine aggregate.

(4) Water – Cement Ratio Method:

According to the water – cement ratio law given by Abram as a result of many experiments, the

strength of well compacted concrete with good workability is dependent only on the ratio.

The lower water content produces stiff paste having greater binding property and hence the

lowering the water-cement ratio within certain limits results in the increased strength.

Similarly, the higher water content increases the workability, but lower the strength of concrete.

The optimum water-cement ratio for the concrete of required compressive strength is decided

from graphs and expressions developed from various experiments.

Amount of water less than the optimum water decreases the strength and about 10% less may be

insufficient to ensure complete setting of cement. An increase of 10% above the optimum may

decrease the strength approximately by 15% while an increase in 50% may decrease the strength

to one-half.

According to Abram’s Law water-cement law, lesser the water-cement ratio in a workable mix

greater will be the strength.

If water cement ratio is less than 0.4 to 0.5, complete hydration will not be secured.

Some practical values of water cement ratio for structure reinforced concrete

0.45 for 1 : 1 : 2 concrete

0.5 for 1 : 1.5 : 3 concrete

0.5 to 0.6 for 1 : 2 : 4 concrete.

Concrete vibrated by efficient mechanical vibrators require less water cement ratio, and hence

have more strength.

Thumb Rules for deciding the quantity of water in concrete:

(i) Weight of water = 28% of the weight of cement + 4% of the weight of total aggregate

(ii) Weight of water = 30% of the weight of cement + 5% of the weight of total aggregate

PROCEDURE:

Check the all component are use in mix design m25 grade concrete.

After checking m25 to take a ratio 1:1:2.

Take cement in 5.7 kg, sand 5.7 and aggregate 11.4 kg.

Aggregate size is 20mm.

To take the water to mix the concrete is to be 3135 ml.

Mix the all component very carefully.

Take a 2 specimen size is 10*10*50.

Volume of one specimen is 0.005 m3.

Fill their specimen for m25 grade concrete.

After filling the specimen dry the specimen in 7 days.

After 7 day the curing process is start in cuboid.

Curing process is done in 28 days.

Flexural strength is to be checked by the flexural test machine.

Test Performed:

For determining the effect of hair as fibre in concrete following tests were performed:

i. Compression test: It is the most common test conducted on hardened concrete as it is an easy

test to perform and also most of the desirable characteristic properties of concrete are

qualitatively related to its compressive strength. The compression test is carried out on

specimens cubical in shape of the size 150 × 150 × 150 mm. The test is carried out in the

following steps: First of all the mould preferably of cast iron, is used to prepare the

specimen of size 150 × 150 × 150 mm. During the placing of concrete in the moulds it is

compacted with the tamping bar with not less than 35 strokes per layer. Then these moulds

are placed on the vibrating table and are compacted until the specified condition is attained. After

24 hours the specimens are removed from the moulds and immediately submerged in clean fresh

water. After 28 days the specimens are tested under the load in a compression testing machine. ii.

Flexural Strength test: Direct measurement of the tensile strength of concrete is difficult. Neither

specimens nor testing apparatushave been designed which assure uniform distribution of the

stress in bending depends on the dimensions of the beam and manner of loading.

pull applied to the concrete. The value of the extreme fibre

The system of loading used in finding out the flexural tension is Third-point Loading Method. In

this method the critical crack may appear at any section, not strong enough to resist the stress

within the middle third, where the bending moment is maximum. The test is carried out in the

following steps: First of all the mould preferably of cast iron, is used to prepare the

specimen of size 150 × 150 × 700 mm During the placing of concrete in the mould it is

compacted with the tamping bar weighing 2 kg, 400 mm long with not less than 35 strokes per

layer. Then this mould is placed on the vibrating table and is compacted until the specified

condition is attained. After 24 hours the specimen is removed from the mould and immediately

submerged in clean fresh water. After 28 days the specimen is taken out from the curing tank and

placed on the rollers of the flexural testing machine as shown in figure 5 for testing. Then the

load is applied at a constant rate of 400 kg/min. The load is applied until the specimen fails, and

the maximum load applied to the specimen during the test is recorded.The specimen for both the

test is made in the following manner: i. Compression test: Three cubes are made for each M-15,

M-2O and M-25 with 0%, 1%, 1.5%, 2%, 2.5% and 3% hair by weight of cement. ii. Flexural

Strength test: One beam is made for each M-15, M-2O and M-25 with 0%, 1%,1.5%, 2%, 2.5%

and 3% hair by weight of cement.

Methodology

The methodology adopted to test the properties and strength of hair reinforced concrete is

governed by: Compressive Strength, Workability test, Flexure test.

Compressive strength of concrete:

Like load, the strength of the concrete is also a quality which varies considerably for the same

concrete mix. Therefore, a single representative value, known as characteristic strength is used.

Characteristic strength of concrete:

It is defined as the value of the strength below which not more then 5% of the test results are

expected to fall (i.e. there is 95% probability of achieving this value only 5% of not achieving

the same)

Characteristic strength of concrete in flexural member

The characteristic strength of concrete in flexural member is taken as 0.67 times the strength of

concrete cube.

Design strength and partial safety factor for material strength

The strength to be taken for the purpose of design is known is known as design strength and is

given by

Design strength (fd) = characteristic strength/ partial safety factor for material strength

The value of partial safety factor depends upon the type of material and upon the type of limit

state. According to IS code, partial safety factor is taken as 1.5 for concrete and 1.15 for steel.

Design strength of concrete in member = 0.45fck

Tensile strength of concrete:

The estimate of flexural tensile strength or the modulus of rupture or the cracking strength of

concrete from cube compressive strength is obtained by the relations

fcr = 0.7 fck N/mm2

The tensile strength of concrete in direct tension is obtained experimentally by split cylinder. It

varies between 1/8 to 1/12 of cube compressive strength.

Creep in concrete:

Creep is defined as the plastic deformation under sustain load. Creep strain depends primarily on

the duration of sustained loading. According to the code, the value of the ultimate creep

coefficient is taken as 1.6 at 28 days of loading.

Shrinkage of Concrete:

The property of diminishing in volume during the process of drying and hardening is termed

Shrinkage. It depends mainly on the duration of exposure. If this strain is prevented, it produces

tensile stress in the concrete and hence concrete develops cracks.

Modular ratio:

Short term modular ratio is the modulus of elasticity of steel to the modulus of elasticity of

concrete.

Short term modular ratio = Es / Ec

Es = modulus of elasticity of steel (2×10 5 N/mm2)

Ec = modulus of elasticity of concrete (5000xSQRT(fck) N/mm2)

As the modulus of elasticity of concrete changes with time, age at loading etc the modular ratio

also changes accordingly. Taking into account the effects of creep and shrinkage partially IS

code gives the following expression for the long term modular ratio.

Long term modular ratio (m) = 280/ (3fcbc)

Where, fcbc = permissible compressive stress due to bending in concrete in N/mm2.

Poisson’s ratio:

Poisson’s ratio varies between 0.1 for high strength concrete and 0.2 for weak mixes. It is

normally taken as 0.15 for strength design and 0.2 for serviceability criteria.

Durability of concrete:

Durability of concrete is its ability to resist its disintegration and decay. One of the chief

characteristics influencing durability of concrete is its permeability to increase of water and other

potentially deleterious materials.

The desired low permeability in concrete is achieved by having adequate cement, sufficient low

water/cement ratio, by ensuring full compaction of concrete and by adequate curing.

Unit weight of concrete:

The unit weight of concrete depends on percentage of reinforcement, type of aggregate, amount

of voids and varies from 23 to 26KN/m2. The unit weight of plain and reinforced concrete as

specified by IS:456 are 24 and 25KN/m3 respectively.

FACTORS AFFECTING THE CHOICE OF MIX PROPORTIONS

The various factors affecting the mix design are:

1. Compressive strength:

It is one of the most important properties of concrete and influences many other describable

properties of the hardened concrete. The mean compressive strength required at a specific age,

usually 28 days, determines the nominal water-cement ratio of the mix. The other factor affecting

the strength of concrete at a given age and cured at a prescribed temperature is the degree of

compaction. According to Abraham’s law the strength of fully compacted concrete is inversely

proportional to the water-cement ratio.

2. Workability:

The degree of workability required depends on three factors. These are the size of the section to

be concreted, the amount of reinforcement, and the method of compaction to be used. For the

narrow and complicated section with numerous corners or inaccessible parts, the concrete must

have a high workability so that full compaction can be achieved with a reasonable amount of

effort. This also applies to the embedded steel sections. The desired workability depends on the

compacting equipment available at the site.

3. Durability:

The durability of concrete is its resistance to the aggressive environmental conditions. High

strength concrete is generally more durable than low strength concrete. In the situations when the

high strength is not necessary but the conditions of exposure are such that high durability is vital,

the durability requirement will determine the water- cement ratio to be used.

4. Maximum nominal size of aggregate :

In general, larger the maximum size of aggregate, smaller is the cement requirement for a

particular water-cement ratio, because the workability of concrete increases with increase in

maximum size of the aggregate. However, the compressive strength tends to increase with the

decrease in size of aggregate.

5. Grading and type of aggregate :

The grading of aggregate influences the mix proportions for a specified workability and water-

cement ratio. Coarser the grading leaner will be mix which can be used. Very lean mix is not

desirable since it does not contain enough finer material to make the concrete cohesive.

Analysis of Data collected:

The analysis of data collected is done in the following manner:

Compression test:

The results from the compression test are in the form of the maximum load the cube can carry

before it ultimately fails. The compressive stress can be found by dividing the maximum load by

the area normal to it. The results of compression test and the corresponding compressive stress .

Let,

P = maximum load carried by the cube before the failure

A = area normal to the load = 150 × 150 mm2 = 22500 mm2

σ = maximum compressive stress (N/mm2

Procedure: Compressive Strength Test of Concrete Cubes

For cube test two types of specimens either cubes of 15cm X 15cm X 15cm or 10cm X 10cm x

10cm depending upon the size of aggregate are used. For most of the works cubical moulds of

size 15cm x 15cm x 15cm are commonly used.

This concrete is poured in the mould and tempered properly so as not to have any voids. After 24

hours these moulds are removed and test specimens are put in water for curing. The top surface

ofhese specimen should be made even and smooth. This is done by putting cement paste and

spreading smoothly on whole area of specimen.

These specimens are tested by compression testing machine after 7 days curing or 28 days

curing. Load should be applied gradually at the rate of 140 kg/cm2 per minute till the Specimens

fails. Load at the failure divided by area of specimen gives the compressive strength of concrete.

Following are the procedure for testing Compressive strength of Concrete Cubes

APPARATUS

Compression testing machine

PREPARATION OF CUBE SPECIMENS

The proportion and material for making these test specimens are from the same concrete used in

the field.

SPECIMEN

6 cubes of 15 cm size Mix. M25

MIXING

Mix the concrete either by hand or in a laboratory batch mixer

HAND MIXING

(i)Mix the cement and fine aggregate on a water tight none-absorbent platform until the mixture

is thoroughly blended and is of uniform color

(ii)Add the coarse aggregate and mix with cement and fine aggregate until the coarse aggregate

is uniformly distributed throughout the batch

(iii)Add water and mix it until the concrete appears to be homogeneous and of the desired

consistency

SAMPLING

(i) Clean the mounds and apply oil

(ii) Fill the concrete in the molds in layers approximately 5cm thick

(iii) Compact each layer with not less than 35strokes per layer using a tamping rod (steel bar

16mm diameter and 60cm long, bullet pointed at lower end)

(iv) Level the top surface and smoothen it with a trowel

CURING

The test specimens are stored in moist air for 24 hours and after this period the specimens are

marked and removed from the molds and kept submerged in clear fresh water until taken out

prior to test.

PRECAUTIONS

The water for curing should be tested every 7 days and the temperature of water must be at 27+-

2oC.

PROCEDURE

(I) Remove the specimen from water after specified curing time and wipe out excess water from

the surface.

(II) Take the dimension of the specimen to the nearest 0.2m

(III) Clean the bearing surface of the testing machine

(IV) Place the specimen in the machine in such a manner that the load shall be applied to the

opposite sides of the cube cast.

(V) Align the specimen centrally on the base plate of the machine.

(VI) Rotate the movable portion gently by hand so that it touches the top surface of the

specimen.

(VII) Apply the load gradually without shock and continuously at the rate of 140 kg/cm2/minute

till the specimen fails

(VIII) Record the maximum load and note any unusual features in the type of failure.

NOTE

Minimum three specimens should be tested at each selected age. If strength of any specimen

varies by more than 15 per cent of average strength, results of such specimen should be rejected.

Average of three specimens gives the crushing strength of concrete. The strength requirements of

concrete.

CALCULATIONS

Size of the cube =15cm x15cm x15cm

Area of the specimen (calculated from the mean size of the specimen )=225 cm2

Characteristic compressive strength(f ck)at 7 days =

Expected maximum load =fck x area x f.s

Similar calculation should be done for 28 day compressive strength

Compressive strength = (Load in N/ Area in mm2)= 24.99.N/mm2

REPORT

a) Identification mark

b) Date of test

c) Age of specimen

d) Curing conditions, including date of manufacture of specimen

f) Appearance of fractured faces of concre

σ = maximum compressive stress (N/mm2).

Compressive strength test results of cube-

Mix Design Avg. Compressive

strength(N/mm^2)

M25 : without hair 24.99

1% hair 25.1

Workability Test

The property of fresh concrete which is indicated by the amount of useful internal work required

to fully compact the concrete without bleeding or segregation in the finished product.

Unsupported fresh concrete flows to the sides and a sinking in height takes place. This vertical

settlement is known as slump. In this test fresh concrete is filled into a mould of specified shape

and dimensions, and the settlement or slump is measured when supporting mould is removed.

Slump increases as water-content is increased. For different works different slump values have

been recommended.

Procedure to determine workability of fresh concrete by slump test.

i) The internal surface of the mould is thoroughly cleaned and applied with a light coat of oil.

ii) The mould is placed on a smooth, horizontal, rigid and nonabsorbent surface.

iii) The mould is then filled in four layers with freshly mixed concrete, each approximately to

one-fourth of the height of the mould.

iv) Each layer is tamped 25 times by the rounded end of the tamping rod (strokes are distributed

evenly over the cross section).

v) After the top layer is rodded, the concrete is struck off the level with a trowel.

vi) The mould is removed from the concrete immediately by raising it slowly in the vertical

direction.

vii) The difference in level between the height of the mould and that of the highest point of the

subsided concrete is measured.

viii) This difference in height in mm is the slump of the concrete.

Reporting of Results

The slump measured should be recorded in mm of subsidence of the specimen during the test.

Any slump specimen, which collapses or shears off laterally gives incorrect result and if this

occurs, the test should be repeated with another sample. If, in the repeat test also, the specimen

shears, the slump should be measured and the fact that the specimen sheared, should be recorded

In case of a dry sample, slump will be in the range of 25-50 mm that is 1-2 inches. But in case of

a wet concrete, the slump may vary from 150-175 mm or say 6-7 inches. So the value of slump is

specifically mentioned along the mix design and thus it should be checked as per your

location.Slump depends on many factors like properties of concrete ingredients – aggregates etc.

Also temperature has its effect on slump value. So these parameters should be kept in mind.

Flexural Strength test

The value of the extreme fibre stress in bending depends on the dimensions of the beam and

manner of loading. The system of loading used in finding out the flexural tension is Third-point

Loading Method as shown in fig 4. In this method the critical crack may appear at any section,

not strong enough to resist the stress within the middle third, where the bending moment is

maximum. The test is carried out in the following steps: First of all the mould preferably of cast

iron, is used to prepare the specimen of size 100 × 100 × 500 mm. During the placing of concrete

in the mould it is compacted with the tamping bar weighing 2 kg, 400 mm long with not less than

25 strokes per layer. Then this mould is placed on the vibrating table and is compacted until the

specified condition is attained. After 24 hour specimen is removed from the mould and

immediately submerged in clean fresh water. After 28 days the specimen is taken out from the

curing tank and placed on the rollers of the flexural testing machine for testing as shown in

figure 4. Then the load is applied at a constant rate of 400 kg/min. The load is applied until the

specimen fails, and the maximum load applied to the specimen during the test is recorded

.

EQUIPMENT & APPARATUS

Beam mould of size 15 x 15x 70 cm (when size of aggregate is less than 38 mm) or of size 10 x

10 x 50 cm (when size of aggregate is less than 19 mm)

Tamping bar (40 cm long, weighing 2 kg and tamping section having size of 25 mm x 25 mm)

Flexural test machine– The bed of the testing machine shall be provided with two steel

rollers, 38 mm in diameter, on which the specimen is to be supported, and these rollers shall be

so mounted that the distance from centre to centre is 60 cm for 15.0 cm specimens or 40 cm for

10.0 cm specimens. The load shall be applied through two similar rollers mounted at the third

points of the supporting span that is, spaced at 20 or 13.3 cm centre to centre. The load shall be

divided equally between the two loading rollers, and all rollers shall be mounted in such a

manner that the load is applied axially and without subjecting the specimen to any torsional

stresses or restraints.

Flexural Strength Test Arrangement

PROCEDURE

Prepare the test specimen by filling the concrete into the mould in 3 layers of approximately

equal thickness. Tamp each layer 35 times using the tamping bar as specified above. Tamping

should be distributed uniformly over the entire crossection of the beam mould and throughout the

depth of each layer.

bearing surfaces of the supporting and loading rollers , and remove any loose sand or other

material from the surfaces of the specimen where they are to make contact with the rollers.

Circular rollers manufactured out of steel having cross section with diameter 38 mm will be used

for providing support and loading points to the specimens. The length of the rollers shall be at

least 10 mm more than the width of the test specimen. A total of four rollers shall be used, three

out of which shall be capable of rotating along their own axes. The distance between the outer

rollers (i.e. span) shall be 3d and the distance between the inner rollers shall be d. The inner

rollers shall be equally spaced between the outer rollers, such that the entire system is systematic.

The specimen stored in water shall be tested immediately on removal from water; whilst they are

still wet. The test specimen shall be placed in the machine correctly centered with the

longitudinal axis of the specimen at right angles to the rollers. For moulded specimens, the

mould filling direction shall be normal to the direction of loading.

The load shall be applied at a rate of loading of 400 kg/min for the 15.0 cm specimens and at a

rate of 180 kg/min for the 10.0 cm specimens.

CALCULATION

The Flexural Strength or modulus of rupture (fb) is given by

fb = pl/bd2 (when a > 20.0cm for 15.0cm specimen or > 13.0cm for 10cm specimen)

or

fb = 3pa/bd2 (when a < 20.0cm but > 17.0 for 15.0cm specimen or < 13.3 cm but > 11.0cm for

10.0cm specimen.)

Where,a= the distance between the line of fracture and the nearer support, measured on the

center line of the tensile side of the specimen

b = width of specimen (cm)

d = failure point depth (cm)

l = supported length (cm)

p = max. Load (kg)

REPORTS

The Flexural strength of the concrete is reported to two significant figures.

SAFETY & PRECAUTIONS:

Use hand gloves while, safety shoes at the time of test.

After test switch off the machine.

Keep all the exposed metal parts greased.

Keep the guide rods firmly fixed to the base & top plate.

Equipment should be cleaned thoroughly before testing & after testing.

Results obtained from flexural strength test and the corresponding

bending strength

S. No Mix % hair Maximum

load (KN)

Bending

stress

(N/mm2)

1. M25 0% 46 4.09

2. M25 1% 47.3 4.21

Problems Encountered: It is well said that: “The taste of defeat has a richness

of,experience all its own.” During our research work we also faced the problem of uniform

distribution of hair in the concrete. So to overcome this problem we have adopted the manual

method of distribution of hair in the concrete.

Future Scope:

The use of waste human hair as a fibre reinforcement in concrete widens the door for further

research in the given field. They are as follows:

i. The distribution matrix of hair in concrete since the resultant matrix could affect the

properties.

ii. The study of admixtures and super plasticizer which could distribute the hairs without

affecting the properties of concrete.

iii. The use of animal hairs in concrete.

Conclusion

Crack formation and propagation are very much reduced showing that hair fibre reinforced

concrete can have various applications in seismic resistant and crack resistant constructions, road

pavement constructions etc. Future scope of this study can be as follows:

During our research work we also faced the problem of uniform distribution of hair in

the concrete. So an efficient method of mixing of hair fibre to the concrete mix is to be

found out.

A wide study on partial replacement of cement using fine hair fibre is to be carried out.

The study of admixtures and super plasticizer which could distribute the hairs without

affecting the properties of concrete.

The use of animal hairs in concrete.

Applications fiber on other properties of composites such physical, thermal properties

and appearances.

The total energy absorbed in fiber as measured by the area under the load deflection

curve is at least 10 to 40 times higher for fiber reinforced concrete than that of plain

concrete.

Addition of hair fiber to conventionally reinforced beams increased the fatigue life and

decreased the cracks width under fatigue loading.

At elevated temperature HFRC have more strength both in compression and tension.

Crack Resistant Structures

According to Grimm, 1988, a crack may be defined as a “break, split, fracture, fissure,

separation, cleavage or elongated narrow opening visible to the normal human eye and

extending from the surface and into a masonry unit, mortar joint, interface between a

masonry unit and adjacent mortar joint”. The cracks are classified according to its

damage level for load bearing masonry. In order to repair cracks up to a width of 5mm,

either cement grouting can be used or steel wire meshes can be inserted into the cracks.

But it is found that when fibre reinforced concrete is used, crack formation and

propagation is very much reduced since fibres can form a strong bond with the concrete

mix and can bridge the cracks to some extent. Examining the concrete specimens after

the tests, it is found that only hair line cracks were formed after the compressive strength

tests cracks in specimens with hair fibre when compared with concrete specimens without

hair fibre content. When fibres are added to concrete, it becomes homogeneous, isotropic

and transforms it to a ductile material. These fibres will act as secondary reinforcement in

concrete and reduces crack formation and propagation. the bridging effect by this fibre

leads to the improvement in the tensile and flexural strength.

Seismic Resistant Structures

Safety against seismic forces is a combination of both structural stability and adoption of

suitable construction techniques. It is well known that it is not the earthquake that kills

people but the collapse of structures that causes the havoc. Light weight construction

techniques have its application in this context. If the structure is light in weight at the

same time stable in structural integrity, the problems caused by the collapse of buildings

can be reduced. The possibility of hair fibre reinforced concrete can be discussed here.

From the experimental results it is obvious that hair fibre reinforced concrete can be used

for ordinary concreting works as such. For reinforced cement concrete, amount of steel

reinforcement can be reduced by adopting required percentage of hair fibre reinforcement

which makes the section light in weight. Reduction in crack formation under service

loads gives better life time for the steel reinforcement as it will resist corrosion of

steel through the cracks. Studies have been put forward the possibility of partial

replacement of cement with fibres in fibre reinforced concrete. If it is feasible, the section

will be economical without compromising the strength.

Road and Pavement Construction

Various studies have been conducted to find the effects of human hair additives in

compressive strength of asphalt cement mixture as potential binder in road pavement and

those prove that adding cement and human hair to asphalt mixture greatly increase the

strength of the mixture thus making it a good material for the construction of road

pavement. Adding of both cement and human hair to asphalt mixture improves the

load bearing capacity of the mixture. Hence hair fibre reinforced concret has its

application in construction of pavements also.

Water Proof Constructions

By adopting hair fibre reinforced concrete the formation of minute cracks can be limited

which reduces the leakage problems, making it suitable for water proof constructions.

Acknowledgement With the deepest sense of gratitude we realize the valuable helps and

encouragement rendered by many individuals during the preparation of this report. We

are deeply grateful to the management and authority of Sahrdaya College of Engineering

And Technology to carry out this work. We also acknowledge with deep gratitude the

help and guidance rendered by the faculty members of civil engineering department who

have always been kind to offer their help in the hours of need. We appreciate the support

given by our friends during this work. Last but not the least, we extent our deep thanks to

our dear parents and God Almighty for guiding us through all difficulties and showering

blessings to fulfil our work.

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