A STUDY ON GLASS FIBRE AS AN ADDITIVE IN CONCRETE TO INCREASE CONCRETE TENSILE STRENGTH

Abstract

The present day world is witnessing the construction of very challenging and difficult civil engineering structures. Glass fiber (also spelled glass fibre) is a material consisting of numerous extremely fine fibers of glass. Quite often, concrete being the most important and widely used material is called upon to possess very high strength and sufficient workability properties. Efforts are being made in the field of concrete technology to develop such concretes with special characteristics. Researchers all over the world are attempting to develop high performance concretes by using fibres and other admixtures in concrete up to certain proportions. Glass-fibre reinforced concrete (GRC) is a material made of a cementatious matrix composed of cement, sand, water and admixtures, in which short length glass fibres are dispersed. It has been widely used in the construction industry for non-structural elements, like façade panels, piping and channels. GRC offers many advantages, such as being lightweight, fire resistance, good appearance and strength. To increase the applications of Glass Fibre Reinforced High-Performance-Concrete (GFRHPC) in India, greater understanding of GFRHPC produced with locally available materials and indigenously produced mineral admixtures is essential.

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Volume : 2 | Issue : 2 | Feb 2013 • ISSN No 2277 - 8160
Research Paper Engineering
A Study on Glass Fibre as an Additive in Concrete to
Increase Concrete Tensile Strength
Ronak
Prakashkumar Patel
Student of final year M.E. in Construction Engineering & Management, B.V.M.
Engineering College, Vallabh Vidyanagar-Gujarat-India
Jayraj Vinodsinh
Solanki
Student of final year M.E. in Construction Engineering & Management, B.V.M.
Engineering College, Vallabh Vidyanagar-Gujarat-India
Jayeshkumar
Pitroda
Assistant Professor and Research Scholar, Civil Engineering Department, B.V.M.
Engineering College, Vallabh Vidyanagar-Gujarat-India
- The present day world is witnessing the construction of very challenging and difficult civil engineering structures.
Glass fiber (also spelled glass fibre) is a material consisting of numerous extremely fine fibers of glass. Quite often,
concrete being the most important and widely used material is called upon to possess very high strength and sufficient
workability properties. Efforts are being made in the field of concrete technology to develop such concretes with special characteristics.
Researchers all over the world are attempting to develop high performance concretes by using fibres and other admixtures in concrete up to
certain proportions. Glass-fibre reinforced concrete (GRC) is a material made of a cementatious matrix composed of cement, sand, water and
admixtures, in which short length glass fibres are dispersed. It has been widely used in the construction industry for non-structural elements, like
façade panels, piping and channels. GRC offers many advantages, such as being lightweight, fire resistance, good appearance and strength. To
increase the applications of Glass Fibre Reinforced High-Performance-Concrete (GFRHPC) in India, greater understanding of GFRHPC produced
with locally available materials and indigenously produced mineral admixtures is essential.
ABSTRACT
KEYWORDS: glass fibre, additive, concrete, rigid pavement, utilization, tensile strength
INTRODUCTION
Glass wool, which is commonly known as “fiberglass” today, however,
was invented in 1938 by Russell Games Slayter of Owens-Corning as a
material to be used as insulation. It is marketed under the trade name
Fiberglas, which has become a genericized trademark. Glass fiber also
called fiberglass. It is material made from extremely fine fibers of glass
Fiberglass is a lightweight, extremely strong, and robust material. Al-
though strength properties are somewhat lower than carbon fiber and
it is less stiff, the material is typically far less brittle, and the raw materi-
als are much less expensive. Its bulk strength and weight properties are
also very favorable when compared to metals, and it can be easily formed
using molding processes. Glass is the oldest, and most familiar, perfor-
mance fiber. Fibers have been manufactured from glass since the 1930s.
TYPES OF FIBER
Steel fiber, Glass fiber, Polypropylene Fiber, Asbestos fiber, Organic fib-
er, Vegetable fiber, Carbon fiber, Polyester fiber etc. are various types of
fiber available in world. Fiber technology is one of the fastest updating
technologies today. There are currently 2,00,000 metric tons of fibers
used for concrete reinforcement.
Figure 1 Fiber used in concrete reinforcement in world
Source: Fly ash utilization in construction – presents status & future
prospects TYPES OF GLASS FIBER As to the raw material glass used to
make glass fibres or nonwovens of glass fibres, the following classifica-
tion is known:
TABLE: 1
TYPES OF GLASS FIBER
A-glass
With regard to its composition, it is close to window
glass. In the Federal Republic of Germany it is mainly
used in the manufacture of process equipment.
C-glass
This kind of glass shows better resistance to chemical
impact.
E-glass
This kind of glass combines the characteristics of C-glass
with very good insulation to electricity.
AE-glass
Alkali resistant glass.
Generally, glass consists of quartz sand, soda, sodium sulphate, potash,
feldspar and a number of refining and dying additives. The characteris-
tics, with them the classification of the glass fibres to be made, are de-
fined by the combination of raw materials and their proportions. Textile
glass fibres mostly show a circular.
PROPERTIES OF GLASS FIBER
• Thermal
Glass fibers are useful thermal insulators because of their high ratio
of surface area to weight. However, the increased surface area makes
them much more susceptible to chemical attack. By trapping air within
them, blocks of glass fiber make good thermal insulation, with a ther-
mal conductivityof the order of 0.05W /(m·K).
• Tensile
The strength of glass is usually tested and reported for “virgin” or pris-
tine fibers—those that have just been manufactured. The freshest,
thinnest fibers are the strongest because the thinner fibers are more
ductile. The more the surface is scratched, the less the resultingtenac-
ity.
TABLE: 2
PROPERTIES OF GLASS FIBRE
Fiber type
E-glass
S-2 glass
Tensile strength (MPa)
3445
4890
Compressive strength (MPa)
1080
1600
Density (g/cm3)
2.58
2.46
Thermal expansion µm/(m°C)
5.4
2.9
Softening T (°C)
846
1056
Price Rs./kg
100
1000
Source: http://en.wikipedia.org/wiki/Glass_fiber

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FIBERS IN RIGID PAVEMENT
Pavements are composite materials that bear the weight of pedestrian
and vehicular loads. Pavement thickness, width and type should vary
based on the intended function of the paved area.
Pavement thickness: It is determined by four factors: environment,
traffic, base characteristics and the pavement material used.
Pavement Width: As with thickness, pavement width should vary
based on its intended use. Interstate highways will obviously need to
be much wider than local residential roads. Similarly, the parking lot
serving a regional shopping center will be much larger than one for a
neighborhood convenience store.
Rigid pavements have sufficient flexural strength to transmit the wheel
load stresses to a wider area below. Compared to flexible pavement,
rigid pavements are placed either directly on the prepared sub-grade
or on a single layer of granular or stabilized material. Since there is only
one layer of material between the concrete and the sub-grade, this
layer can be called as base or sub-base course.
TypesofRigidPavements
Rigid pavements can be classified into four types:
• Jointedplainconcretepavement(JPCP)
• Jointedreinforcedconcretepavement(JRCP)
• Continuousreinforcedconcretepavement(CRCP)
• Pre-stressedconcretepavement(PCP)
Failurecriteriaofrigidpavements
Fatigue cracking has long been considered as the major or only criteri-
on for rigid pavement design. The allowable number of load repetitions
to cause fatigue cracking depends on the stress ratio between flexural
tensile stress and concrete modulus of rupture. Of late, pumping is
identified as an important failure criterion. Pumping is the ejection
of soil slurry through the joints and cracks of cement concrete pave-
ment, caused during the downward movement of slab under the heavy
wheel loads. Other major types of distress in rigid pavements include
faulting, spalling, and deterioration. So to reduce the cracks developed
in the concrete, fibers are used to stick the concrete surfaces. It will not
separate the particles of the materials used in concrete.
BENEFITS OF GLASS FIBER REINFORCED CONCRETE
(GFRC)
There are lots of good reasons to use GFRC for thin sections of concrete:
• Lighterweight:WithGFRC,concretecanbecastinthinnersections
and is therefore as much as 75% lighter than similar pieces cast
withtraditionalconcrete.According to Je Girard’s blog post ti-
tled, The Benefits of Using a GFRC Mix for Countertops, a concrete
countertop can be 1-inch thick with GFRC rather than 2 inches
thick when using conventional steel reinforcement.
• Highstrength:GFRCcanhaveexuralstrengthashighas4000psi
and it has a very high strength-to-weight ratio.
• Reinforcement: Since GFRC is reinforced internally, there is no
need for other kinds of reinforcement, which can be difficult to
place into complex shapes.
• Consolidation: For sprayed GFRC, no vibration is needed. For
poured, GFRC, vibration or rollers are easy to use to achieve con-
solidation.
• Equipment:Expensiveequipmentisnotneededforpouredorvi-
brated GFRC with a face coat; for sprayed GFRC, equipment gener-
ally costs about Rs. 50,000.
• Toughness:GFRCdoesn’tcrackeasily—itcanbecutwithoutchip-
ping.
• Surface nish: Because it is sprayed on, the surface has no bug
holes or voids.
• Adaptability:Sprayedorpoured intoa mold,GFRC canadaptto
nearly any complex shape, from rocks to fine ornamental details.
• Durability:AccordingtoACI544.1R-96,State of the Art Report on
Fiber Reinforced Concrete, “The strength of fully-aged GFRC com-
posites will decrease to about 40 percent of the initial strength pri-
or to aging.” Michael Driver, division manager with Nippon Electric
Glass,amajormanufacturerofARglassbers,disagrees.“There’s
neveradurabilityissue.Watercan’tgetin—therearenocracks—
andthat’sadurablematerial.GFRCwilloutlastprecastconcrete,
cast stone, even some natural stone.” Durability has been increased
through the use of low alkaline cements and pozzolans.
• Sustainable:Becauseituseslesscementthanequivalentconcrete
and also often uses significant quantities of recycled materials (as
a pozzolan), GFRC qualifies as sustainable.
TABLE: 3
APPLICATIONS OF GLASS FIBRE
Architecture Building Engineering
Prefabricated
architectural
cladding,architectural
moldings and
features,Environments
& Landscaping.
Industrial and
agricultural
roofing,Walls and
Windows, Renovation,
Foundations and Floors,
Modular Buildings.
Permanent
Formwork, Utilities,
Acoustics, Bridges
and Tunnels, Water
and Drainage.
CASE STUDY
“Effect of Glass Fibres on Ordinary Portland Cement Concrete” Desh-
mukhS.H.,BhusariJ.P,ZendeA.M
Concrete is a tension weak building material, which is often crack rid-
den connected to plastic and hardened states, drying shrinkage, and
the like. Moreover, concrete suffers from low tensile strength, limited
ductility and little resistance to cracking. In order to improve these
properties, and attempt has been made to study the effect of addition
of glass fibers in ordinary Portland cement concrete. In the present ex-
perimental investigation glass fibers in different percentage 0 to 0.1%
has been studied for the effect on mechanical properties of concrete by
carrying compressive strength test, flexural strength test and splitting
tensile strength test. The results have shown improvement in mechani-
cal and durability properties with the addition of glass fibers.
In this study, control mix A was designed as per IS 10262:1982 to
achieve a target compressive strength of 20 N/mm2. The glass fibres of
0 %, 0.03%, 0.06% and 0.1 % by volume fraction of concrete were used.
TABLE: 4
COMPRESSIVE STRENGTH, FLEXURAL STRENGTH, SPLIT-
TING TENSILE STRENGTH TEST RESULTS AT 28 DAYS
Type of concrete
Average
compressive
Strength N/
mm2
Average
Flexural
Strength N/
mm2
Average
Splitting
Tensile
Strength N/
mm2
M-20 with 0.0% glass
fiber
23.93 3.344
3.22
M-20 with 0.03% glass
fiber
26.07 3.587
3.31
M-20 with 0.06% glass
fiber
26.6 3.654
3.63
M-20 with 0.1% glass
fiber
29.54 3.99
4.58
CONCLUSIONS
As we know the concrete is poor in taking tension so to improve its ten-
sile strength we can add glass fibres due to which the filaments of glass
fibre will not separate the particles of concrete. The addition of glass
fibres into the concrete mixture marginally improves the compressive
strength at 28 days. It is observed from the experimental results, that
the compressive strength of concrete, flexural strength of concrete,
splitting tensile strength of concrete increases with addition of Percent-
age of glass fibers. The 0.1% addition of glass fibers into the concrete
shows better result in mechanical properties and durability.
ACKNOWLEDGMENTS
The Authors thankfully acknowledge to Dr.C.L.Patel, Chairman, Charu-
tarVidyaMandal,Er.V.M.Patel,Hon.Jt.Secretary,CharutarVidyaMandal,
Mr.YatinbhaiDesai,JayMaharajconstruction,Dr.F.S.Umrigar,Principal,
B.V.M. Engineering College, Dr.A.K.Verma, Head & Professor, Structural
Engineering Department, Dr.B.K.Shah, Associate Professor, Structural
Engineering Department, B.V.M. Engineering College, Vallabh Vidyana-
gar, Gujarat, India for their motivational and infrastructural support to
carry out this research.

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