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REVIEW OF LITERATURE
The idea of adding a fibre or fibres into concrete in order to increase
strength and fracture energy goes back to a patent dated 1918 by H. Alfsen and this fact
is reported by Katzer . Alfsen described a process to improve the tensile strength by
adding longitudinal bodies (fibres) of different materials into the concrete. Afterwards
several patents of different fibres and fibre geometries were proclaimed. In this chapter
studies on the High Performance Concrete, Fibre reinforced Concrete, Hybrid Fibre
Reinforced concrete and Ultra High Peformance Fibre Reinforced Concrete is reviewed.
2.2 STUDIES ON HIGH PERFORMANCE CONCRETE
High performance concrete (HPC) is a specialized series of concrete
designed to provide several benefits in the construction of concrete structures that
cannot always be achieved routinely using conventional ingredients, normal mixing and
curing practices. In other words a high performance concrete is a concrete in which
certain characteristics are developed for a particular application and environment, so
that it will give excellent performance in the structure in which it will be placed, in the
environment to which it will be exposed, and with the loads to which it will be
subjected during its design life.
It includes concrete that provides either substantially improved resistance to
environmental influences (durability in service) or substantially increased structural
capacity while maintaining adequate durability. It may also include concrete, which
significantly reduces construction time without compromising long-term serviceability.
While high strength concrete, aims at enhancing strength and consequent advantages
owing to improved strength, the term high-performance concrete (HPC) is used to refer
to concrete of required performance for the majority of construction applications.
The American Concrete Institute Committee 1993  on HPC includes the
following six criteria for material selections, mixing, placing, and curing procedures for
concrete. They are (1) Ease of placement, (2) Long term mechanical properties,
(3) Early-age strength, (4) Toughness, (5) Life in severe environments and
(6) Volumetric stability
The above-mentioned performance requirements can be grouped under the
following three general categories.
(a) Attributes that benefit the construction process
(b) Attributes that lead to enhanced mechanical properties
(c) Attributes that enhance durability and long-term performance.
The performance requirements of concrete cannot be the same for different
applications. Hence the specific definition of HPC required for each industrial
application is likely to vary. The Strategic Highway Research Programme (SHRP) 
has defined HPC for highway application on the following strength, durability, and
water-cement ratio criteria.
1. a maximum water-cementitious ratio (W/C) of 0.35;
2. a minimum durability factor of 80% after 300 cycles of freezing and
3. a minimum strength criteria of either
(a) 21 MPa within 4 hours after placement (Very Early Strength, VES),
(b) 34 MPa within 24 hours (High Early Strength, HES), or
(c) 69 MPa within 28 days (Very High Strength, VHS).
In general, a ―High performance Concrete‖ can be defined as that concrete
which has the highest durability for any given strength class, and comparison between
the concretes of different strength classes is not appropriate. This means that, with the
available knowledge, one can always strive to achieve a better (most durable) concrete
required for a particular application
The use of high performance concrete results in many advantages, such as
reduction in beam and column sizes and increase in the building height with many
stories. In pre-stressed concrete construction, a greater span-depth ratio for beams may
be achieved with the use of high performance concrete. In marine structures, the low
permeability characteristics of high performance concrete reduce the risk of corrosion of
steel reinforcement and improve the durability of concrete structures. In addition, high
performance concrete can perform much better in extreme and adverse climatic
conditions, and can reduce maintenance and repair costs [21, 22, 23]. Hence, HPC
concretes are used for numerous applications and the studies related to HPC are
Yogendran et al. (1987), have studied extensively High Strength Concrete
using Silica Fume with no air entrainment to achieve compressive strength in the range
of 50 to 70MPa in which cement was replaced by silica fume (0 to 30 percent by
weight) . The efficiency of silica fume in improving the properties of concrete was
compared at medium and very low water cementitious ratios. Concretes with water
cementitious ratios of 0.34 and 0.28 with and without a superplasticizer, at a constant
slump (50 mm) and with varying slump were also investigated. It has been concluded
that for concretes with 5 to 30 percent replacement of cement by silica fume and a
constant slump of 50 mm there was no increase in water demand up to 5 percent
replacement. The water required to maintain a constant slump, however, increased
linearly as the percentage of silica fume replacement increased from 10 to 30 percent.
A 5 percent replacement produced the highest compressive strength at 7 and 28 days.
Replacement of 10 percent and 15 percent produced strength equal to the control mix at
7 and 28 days. Replacement levels of 25 percent and 30 percent produced lower
strengths at all test ages.
Ganesh Babu et al. (1993), has evaluated the efficiency of flyash in concrete
over a wide range of percentage replacements (15-75%) . It was concluded that at
the replacement percentage of flyash and the water cement ratios increase the strength
of concrete decreases. It has been reported that while concretes above 70 MPa can be
produced with replacements up to 25% fly ash, replacements of about 75% can still lead
to concretes of 40 MPa through suitable adjustments in water/cement ratio and other
concrete constituents. It has been predicted that the strength of concretes varying from
20 to 100 MPa with Ground Granulated Blast Furnace Slag (GGBS) levels varying from
10% to 80% was found to result in a regression coefficient of 0.94, which was also the
same for normal concretes.
Khatri et al. (1995), has investigated the effect of different supplementary
cementitious materials on mechanical properties of high performance concrete . The
investigation focussed on to compare the mechanical properties as well as fresh concrete
properties of concretes containing silica fume, ground granulated blast furnace slag,
fly ash and General Purpose (GP) Portland cement. Concrete mixes were prepared with
GP Portland cement, high slag cement and slag cement, and also mixes were prepared
with the addition of silica fume and fly ash The work focussed on concrete mixes
having a fixed water/binder ratio of 0.35 and a constant total binder content of
430 kg/m 3 . Apart from measuring fresh concrete properties, the mechanical properties
evaluated were development of compressive strength, flexural strength, elastic modulus,
and strain due to creep and drying shrinkage. The compressive strength of concrete
containing GP cement, fly ash and silica fume is higher (46%) compared to the
compressive strength of concrete containing only GP cement at the age of 28 days. It
was also observed that the addition of silica fume significantly increases the flexural
strength (45%) of GP concrete. The addition of silica fume also improved the elastic
modulus of GP concrete.
Duval et al. (1998), has studied the influence of silica fume on the
workability and the compressive strength of high-performance concretes . The
workability and the compressive strength of silica fume concretes were investigated at
low water-cementitious materials ratios with a naphthalene sulphonate superplasticizer.
The results show that partial cement replacement up to 10% silica fume does not reduce
the concrete workability. Moreover, the superplasticizer dosage depends on the cement
characteristics (C3A and alkali sulfates content). At low water-cementitious materials
ratios, slump loss with time was observed and increases with high replacement levels.
Silica fume at replacement contents up to 20% produce higher compressive strengths
than control concretes.
Shannag (2000), has studied the mechanical properties of High strength
concrete containing natural pozzolan and silica fume . Various combinations of a
local natural pozzolan and silica fume were used to produce workable high to very high
strength mortars and concretes with a compressive strength in the range of
69 – 110 MPa. The mixtures were tested for workabilit