High Performance Concrete

High Performance Concrete
Unit-IV

Syllabus
• High Performance Concrete: Concrete of High Grades,
various tests and application of high performance concrete

High Strength Concrete
• Based on the compressive strength; concrete is normally classified as
normal strength concrete, high strength concrete and ultra strength
concrete. Indian standard recommended methods of mix design denotes
the boundary at 35 Mpa between normal strength and high strength
concrete.
• The advent of pre-stressed concrete techniques has given impetus for
making concrete of higher strength. High strength concrete is necessary
for the construction of high rise building and long span bridges.
• To achieve high strength, it necessary to use high cement content with the
lowest possible W/C ratio which invariable affect the workability of the
mix. It should be remembered that high cement content may liberate large
heat of hydration causing rise in temperature which may affect setting
and may result in excessive shrinkage.

• Various methods of producing high strength concrete are:
• (i) Seeding
• (ii) Revibration
• (iii) Inhibiting Cracks
• (iv) Using admixtures
• (v) Sulphur impregnation
• Seeding is a process of adding a small quantity of finely ground, fully hydrated
Portland cement to the fresh concrete mix.
• Revibration of plastic concrete also improves the strength of concrete. Concrete
undergoes plastic shrinkage. Mixing water creates continuous capillary channels
and bleeding, reducing strength of concrete. Revibration removes all these
defects and increases the strength of concrete.

Special methods of making high strength concrete
Seeding: This involves adding a small percentage of finely ground, fully hydrated Portland cement
to the fresh concrete mix.
 Revibration: Controlled revibration removes all the defects like bleeding, water accumulates ,
plastic shrinkage, continuous capillary channels and increases the strength of concrete.
 High speed slurry mixing: This process involves the advance preparation of cement - water
mixture which is then blended with aggregate to produce concrete.
Use of admixtures: Use of water reducing agents are known to produce increased compressive
strength.

Inhibition of cracks: If the propagation of cracks is inhibited, the
strength will be higher.
Concrete cubes made this way have yielded strength up to 105MPa.
Sulphur Impregnation: Satisfactory high strength concrete have been
produced by impregnating low strength porous concrete by sulphur.
The sulphur infiltrated concrete has given strength up to 58MPa.
Use of Cementitious aggregates: Using slag as aggregate, strength up to
25MPa has been obtained with water cement ratio 0.32.

• Various methods of producing high strength concrete are:
• In conventional concrete, micro-cracks develop even before loading
because of drying shrinkage and other volume change. When the
structure is loaded the micro cracks open up and propagate. The
weakness can be removed by inclusion of small, closely spaced and
uniformly dispersed fibres in concrete.
• Use of water reducing agents are known to produce increased
compressive strength.

• The development of high performance concrete (HPC) is a giant step
in making concrete a high-tech material with enhanced
characteristics and durability. High performance concrete is an
engineered concrete obtained through a careful selection and
proportioning of its constituents. The concrete is with the same basic
ingredients but has a totally different microstructure than ordinary
concrete.

• The low water cement ratio of HPC results in a very dense microstructure
having a very fine and more or less well connected capillary system.
• The dense microstructure of HPC, makes the migration of aggressive ions
more difficult, consequently HPC is more durable when exposed to
aggregate environment conditions.
• High performance concrete can hence be defined as an engineered
concrete with low water/ binder ratio to control its dimensional stability
and when receive an adequate curing.
• The cementitious component of high or any combination of cementitious
material such as slag, fly ash, silica fume, metakaolin and filler such as,
limestones.

• Concrete compressive strength is closely related to the density of hardened
matrix. High performance concrete has also taught us that the coarse
aggregate can be the weakest link in concrete when the strength of
hydrated cement paste is drastically increased by lowering the
water/binder ratio. In such case concrete failure can start to develop
within the coarse aggregate itself. As a consequence, there can be
exceptions to the water/ binder ratio law when dealing with HPC. When
the concrete’s compressive strength is limited by the coarse aggregate, the
only way to get higher strength is to use a stronger aggregate.
• •If water curing is essential to develop the potential strength of cement in
plain concrete, early water curing is crucial for high-performance
concrete in order to avoid the rapid development of autogenous shrinkage
and to control concrete dimensional stability, as explained below.

• The hydration of cement paste is accompanied by an absolute volume
contraction that creates a very fine pore network within the hydrated
cement paste. This network drains water from coarse capillaries,
which start to dry out if no external water is supplied. Therefore, if
no drying is occurring and no external water is added during curing,
the coarse capillaries will be empty of water as hydration progresses.
This phenomenon is called self desiccation. The difference between
drying and self-desiccation is that, when concrete dries water
evaporates to the atmosphere, while during-self desiccation water
stay within the concrete i.e. It only migrates towards the very fine
pores created by the volumetric contraction of the cement paste.

• HPC must be cured quite differently from ordinary concrete because
of the difference in shrinkage behaviour. The ordinary concrete
exhibits no autogeneous shrinkage whether it is water cured or not,
where as HPC can experience significant autogenous shrinkage if it
is not water cured during the hydration process. While curing
membranes provide adequate protection for ordinary concrete, they
can only help prevent the development of plastic shrinkage in HPC.
They have no value in inhibiting autogenous shrinkage. Therefore,
the most critical period for any HPC runs from placement or
finishing up to 2 to 3 days later

• During this time the most critical period is usually from 12 to 36
hours. In fact, the short time during which efficient water curing
must be applied to HPC can be considered a significant advantage
over ordinary concrete.. In fact, the short time during which efficient
water curing must be applied to HPC can be considered a significant
advantage over ordinary concrete. Water ponding, whenever
possible or fogging are the best ways to cure HPC.

• Concrete is the most widely used construction material in India with annual
consumption exceeding 100 million cubic metres. It is well known that
conventional concrete designed on the basis of compressive strength does not
meet many functional requirements such as impermeability, resistance to frost,
thermal cracking adequately.
• Conventional Portland cement concrete is found deficient in respect of:
• Durability in severe environs (Shorter service life and require maintenance)
• Time of construction (longer release time of forms and slower gain of strength)
• Energy absorption capacity (for earthquake-resistant structures)
• Repair and retrofitting jobs
• High performance concrete (HPC) successfully meets the above requirement.

• 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 the
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.

“High performance Concrete”
• 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.

• 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.

• HPC is a concrete, which meets special performance, and
uniformity requirements that cannot be always achieved by
using only the conventional materials and normal mixing,
placing, and curing practices. The performance
requirements may involve enhancement of placement and
compaction without segregation and long term mechanical
properties, early age strength, toughness, volume stability,
service life.

• A High Performance concrete element is that which is designed to give optimized
performance characteristics for a given set of load, usage and exposure conditions,
consistent with requirement of cost, service life and durability.
• High Performance concrete has,
• (a) Very low porosity through a tight and refined pore structure of the cement paste.
• (b) Very low permeability of the concrete
• (c) High resistance to chemical attack.
• (d) Low heat of hydration
• (e) High early strength and continued strength development
• (f) High workability and control of slump
• (g) Low water binder ratio
• (h) Low bleeding and plastic shrinkage

HPC Definition
• American Concrete Institute (ACI)
• A more broad definition of HPC was adopted by the ACI. HPC was
defined as concrete, which meets special performance and
uniformity requirements that cannot be always be achieved routinely
by using only conventional materials and normal mixing, placing
and curing practices. The requirements may involve enhancement of
placement and compaction without segregation, long term
mechanical properties, early age strength, volume stability or service
life in severe environments. Concretes possessing many of these
characteristics often achieve higher strength. Therefore, HPC is often
of high strength, but high strength concrete may not necessarily be of
high performance.

Composition of High Performance Concrete
• The composition of HPC usually consists of cement, water, fine sand,
super-plasticizer, fly ash and silica fume. Sometimes, quartz flour and
fibre are the components as well for HPC having ultra strength and ultra
ductility, respectively. The key elements of high performance concrete can
be
• summarized as follows:
• Low water-to-cement ratio,
• Large quantity of silica fume (and/or other fine mineral powders),
• Small aggregates and fine sand,
• High dosage of super-plasticizers,
• Heat treatment and application of pressure which are necessary for ultra
high strength concrete after mixing (at curing stage).

Composition of High Performance Concrete

Key Features of High Performance Concrete
• HPC should have a better performance when compared to
normal strength concrete. Three of the key attributes to HPC
are, strength, ductility and durability.

Strength
• In practice, concrete with a compressive strength less than 50MPa is regarded as
NSC, while high strength concrete (HSC) may be defined as that having a
compressive strength of about 50MPa.
• Recently, concrete with the compressive strength of more than 200MPa has been
achieved. Such concrete is defined as ultra high strength concrete. As the
compressive strength of concrete has been steadily increasing with ample
experimental validation
• In general, the addition of admixture does not improve the concrete strength
only. Usually, other aspects of performance, like ductility and durability, are also
enhanced

Key Features of High Performance Concrete

Table shows the characteristics of different type of
with various compositions.

Ductility
• HPC is usually more brittle when compared with NSC,
especially when high strength is the main focus of the
performance. Ductility can be improved by applying a
confining pressure on HPC. Besides confinement, the
ductility of HPC can be improved by altering its composition
through the addition of fibres in the design mix. Concrete
with fibres inside is regarded as fibber reinforced concrete
(FRC).

Durability
• Many researchers have conducted investigations related to
concrete durability and have identified that the majority of
concrete durability problems are related to the resistance of
concrete to permeation of water and chemical ions. Such
problems include corrosion of steel reinforcement, freeze-
thaw damage, and alkaline-silica reaction.

Durability
• The permeability of concrete is a key factor influencing the
durability of concrete. Concrete permeability is dependent
on permeability of each constituent material and its
geometric arrangement.
• The permeability of cement paste is primarily related to pore
structure, which includes porosity, pore size and
connectivity; while pore structure is a function of the water-
to-cement ratio and the degree of hydration.

Methods for achieving High Performance
• In general, better durability performance has been achieved by using
high-strength, low w/c ratio concrete. Though in this approach the design
is based on strength and the result is better durability, it is desirable that
the high performance, namely, the durability, is addressed directly by
optimizing critical parameters such as the practical size of the required
materials.
• Two approaches to achieve durability through different techniques are as
follows.
• (1) Reducing the capillary pore system such that no fluid movement can
occur is the first approach. This is very difficult to realize and all concrete
will have some interconnected pores.
• (2) Creating chemically active binding sites which prevent transport of
aggressive ions such as chlorides is the second more effective method.

Methods for achieving High Performance

Requirements for High-performance
Characteristics
• Permeation is a major factor that causes premature
deterioration of concrete structures.
• The provision of high-performance concrete must centre on
minimizing permeation through proportioning methods and
suitable construction procedures (curing) to ensure that the
exposure conditions do not cause ingress of moisture and
other agents responsible for deterioration.

Requirements for High-performance
Characteristics
• Permeation can be divided into three distinct but connected stages of
transportation of moisture, vapour, air, gases, or dissolved ions.
• It is important to identify the dominant transport phenomenon and
design the mix proportion with the aim of reducing that transport
mechanism which is dominant to a predefined acceptable
performance limit based on permeability.

salient high-performance requirements

Salient High-performance Requirements

Salient High-performance Requirements
• The parameter to be controlled for achieving the required performance criteria could be
any of the following.
• (1) Water/ (cement + mineral admixture) ratio
• (2) Strength
• (3) Densification of cement paste
• (4) Elimination of bleeding
• (5) Homogeneity of the mix
• (6) Particle size distribution
• (7) Dispersion of cement in the fresh mix
• (8) Stronger transition zone
• (9) Low free lime content
• (10) Very little free water in hardened concrete

Material Selection
• The main ingredients of HPC are almost the same as that of conventional
concrete.
• These are
• 1) Cement
• 2) Fine aggregate
• 3) Coarse aggregate
• 4) Water
• 5) Mineral admixtures (fine filler and/or pozzolonic supplementary
cementations materials)
• 6) Chemical admixtures (plasticizers, super plasticizers, retarders, air-
entraining agents)

Material Selection
Cement
• There are two important requirements for any cement:
• (a) strength development with time and
• (b) facilitating appropriate rheological characteristics when fresh.
• 1) High C3A content in cement generally leads to a rapid loss of flow
in fresh concrete. Therefore, high C3A content should be avoided in
cements used for HPC.
• 2) The total amount of soluble sulphate present in cement is a
fundamental consideration for the suitability of cement for HPC.

Material Selection
• 3) The fineness of cement is the
critical parameter. Increasing fineness
increases early strength development,
but may lead to rheological
deficiency.
• 4) The super-plasticizer used in HPC
should have long molecular chain in
which the sulphate group occupies
the beta position in the poly
condensate of formaldehyde and
melamine sulphate or that of
naphthalene sulphate.
• 5) The compatibility of cement with
retarders, if used, is an important
requirement.

Material Selection
Coarse aggregate
• The important parameters of coarse aggregate that influence the
performance of concrete are its shape, texture and the maximum size.
Since the aggregate is generally stronger than the paste, its strength is not
a major factor for normal strength concrete, However, the aggregate
strength becomes important in the case of high performance concrete.
Surface texture and mineralogy affect the bond between the aggregates
and the paste as well as the stress level at which micro cracking begins.
The surface texture, therefore, may also affect the modulus of elasticity, the
shape of the stress-strain curve and to a lesser degree, the compressive
strength of concrete. Since bond strength increases at a slower rate than
compressive strength, these effects will be more pronounced in High
strength concrete. Tensile strengths may be very sensitive to differences in
aggregate surface texture and surface area per unit volume.

Material Selection
Mineral admixtures
• Mineral admixtures form an essential part of the high-performance
concrete mix. These are used for various purposes, depending upon their
properties. More than the chemical composition, mineralogical and
granulometric characteristics determine the influence of mineral
admixture's role in enhancing properties of concrete. The fly ash (FA), the
ground granulated blast furnace slag (GGBS) and the silica fume (SF) has
been used widely as supplementary cementitious materials in high
performance concrete. These mineral admixtures, typically fly ash and
silica fume (also called condensed silica or micro silica), reduce the
permeability of concrete to carbon dioxide (CO2) and chloride-ion
penetration without much change in the total porosity.

Material Selection
• Fly ash used as a partial replacement for cement in concrete, provides very
good performance. Concrete is durable with continued increase in
compressive strength beyond 28 days. There is little evidence of
carbonation, it has low to average permeability and good resistance to
chloride-ion penetration.
• Silica fume not only provides an extremely rapid pozzolanic reaction, but
its very fine size also provides a beneficial contribution to concrete. Silica
fume tends to improve both mechanical properties and durability. Silica
fume concretes continue to gain strength under a variety of curing
conditions, including unfavourable ones. Thus the concretes with silica
fume appear to be more robust to early drying than similar concretes that
do not contain silica fume.
• Silica fume is normally used in combination with high-range water
reducers and increases achievable strength levels dramatically.

summary of the characteristics of different
mineral admixtures

mineral admixtures
Super-plasticizers or HRWR
• The super-plasticizers are extensively used in HPCs with very low water cementitious
material ratios. In addition to de-flocculation of cement grains and increase in the
fluidity, the other phenomena that are likely to be present are the following.
• (a) Induced electrostatic repulsion between particles.
• (b) Dispersion of cement grains and consequent release of water trapped within cement
flocks.
• (c) Reduction of surface tension of water.
• (d) Development of lubrication film between particles.
• (e) Inhibition of the surface hydration reaction of the cement particles, leaving more
water to fluidity the mix.
• (f) Change in morphology of hydration products.
• (g) Induced steric-hindrance preventing particle to particle contact.

mineral admixtures
• The main objectives for using super-plasticizers are the following.
• (i) To produce highly dense concrete to ensure very low permeability with adequate resistance to
freezing-hawing.
• (ii) To minimize the effect of heat of hydration by lowering the cement content.
• (iii) To produce concrete with low air content and high workability to ensure high bond strength.
• (iv) To lower the water-cement ratio in order to keep the effect of creep and shrinkage to a
minimum.
• (v) To produce concrete of lowest possible porosity to protect it against external attacks.
• (vi) To keep alkali content low enough for protection against alkali-aggregate reaction and to
• keep sulphate and chloride contents as low as possible for prevention of reinforcement corrosion.
• (vii) To produce pumpable yet non-segregating type concrete.

mineral admixtures
• Retarders
• Retarders are, generally, recommended for HSC to minimize the
slump loss problem.
• However, it is difficult to maintain compatibility between the
retarder and the super plasticizer.
• Therefore, the Retarders are recommended only as a last resort; the
rheology is better controlled by the use of appropriate mineral
admixture (supplementary cementing material) discussed before

Mix Proportion
• The main difference between mix designs of HPC and CC is the emphasis laid on
• performance aspect also (in fresh as well as hardened stages of concrete) besides
strength, in case of HPC, whereas in design of CC mixes, strength of concrete is an
important criterion. By imposing the limitations on maximum water–cement ratio,
minimum cement content, workability (slum, flow table, compaction factor, Vee-Bee
consistency), etc., it is sought to assure performance of CC; rarely any specific tests are
conducted to measure the durability aspects of CC, during the mix design. In HPC,
however, besides strength, durability considerations are given utmost importance. To
achieve high durability of HPC, the mix design of HPC should be based on the following
considerations:
• i) The water-binder (w/b) ratio should be as less as possible, preferably 0.3 and below.
• ii) The workability of concrete mix should be enough to obtain good compaction (use
suitable
• chemical admixtures such as super-plasticizer (SP)).
• iii) The transition zone between aggregate and cement paste should be strengthened
(add fine
• fillers such as silica fume (SF)).

Properties of High Performance Concrete
Properties of Fresh Concrete
• High performance concrete is characterized by special performance both short-
and long-term and uniformity in behaviour. Such requirements cannot always
be achieved by using only conventional materials or applying conventional
practices.
• It is wrong to believe that the mechanical properties of high performance
concrete are simply those of a stronger concrete. It is also as wrong to consider
that the mechanical properties of high-performance concrete can be deduced by
extrapolating those of usual concretes as it would be wrong to consider that
none of them are related. It is also wrong to apply blindly the relationships
linking the mechanical properties of a usual concrete to its compressive strength
that were developed through the years for usual concretes found in codes and
text books.

Workability
• The workability of HPC is normally good, even at low slumps, and HPC
typically
• pumps very well, due to the ample volume of cementing material and the
presence of chemical admixtures, particularly HRWR. Due to reduced
water-cementing material ratio no bleeding occurs. In the flowing
concrete bleeding is prevented by providing adequate fines in the concrete
mix. The cohesiveness of super-plasticized concrete is much better as a
result of better dispersion of cement particles. Cohesion is a function of
rheology of concrete mix, which is consequently improved. However,
excessive dosages of super-plasticizer can induce some segregation, but it
has little effect on physical properties of hardened concrete.

Curing
• The compressive strength of HPC is less sensitive to temperature and relative
humidity than the normal strength concrete. However, tensile strength of HSC
has been found to be more sensitive. The concrete containing very large
quantities of ground granulated blast furnace slag requires longer moist curing
times to develop adequate strength and is more sensitive to drying than plain
Portland cement concretes.
• The higher internal temperatures frequently found with high early strength HPC
can lead to a rapid strength gain in concrete accompanied by a consequent gain
in elastic modulus.
• The larger differential temperatures occurring within a stiffer concrete will
create higher stresses and can cause more pronounced cracking than with
normal concrete. These cracks will occur, regardless of the method of curing,
due to stress caused by differential temperatures.

Properties of Hardened concrete
• The behaviour of hardened concrete can be characterized in terms of
its short-term (essential instantaneous) and long-term properties.
Short-term properties include strength in compression, tension and
bond, and modulus of elasticity. The long-term properties include
creep, shrinkage, behaviour under fatigue, and durability
characteristics such as porosity,
• permeability, freezing-thawing resistance, and abrasion resistance.

Application of High Performance Concrete
• Application of High Performance Concrete
• Major applications of HPC have been in the areas of pavements, long-span
bridges and high-rise buildings.
• Pavements:
• High Performance concrete is being increasingly used for highway pavements
due to the potential economic benefits that can be derived from the early
strength gain of high performance concrete, its reduced permeability, increased
wear or abrasion resistance to steel studded tires and improved freeze-thaw
durability. While the conventional normal strength concrete continue to be used
in most cases of pavement construction, different types of high performance
concretes are being considered for pavement repairs for early opening to traffic,
bridge deck overlays, and special applications in rehabilitation of structures and
other developments.

• A durable concrete called fast track concrete designed to give high strength at a very
early age without using special materials or techniques has been developed. The early
strength is controlled by the water-cement ratio, cement content and its characteristics.
Typically, a rich, low water content mix containing 1 to 2 per cent calcium chloride will
produce adequate strength and abrasion resistance for opening the pavement to traffic
in 4-5 hours at temperatures above 100C. Fast track concrete paving (FTCP) technology
can be used for complete pavement reconstruction, partial replacement by an inlay of at
least one lane, strengthening of existing bituminous or concrete pavements by a
concrete overlay, rapid maintenance and reconstruction processes, and air-field
pavements. The benefits of applying FTCP technology in such applications are: a reduced
construction period, early opening of the pavement to traffic, and minimizing the use of
expensive concrete paving plant. Flowable HSC overlays over thick bridge decks can
make the construction cost effective.

• Bridges:
• The use of high performance concrete would result in smaller loss pre-stress and
consequently larger permissible stress and smaller cross-section being achieved,
i.e. it would enable the standard pre-stressed concrete girders to span longer
distances or to carry heavier loads. In addition, enhanced durability allow
extended service life of the structure. In case of precast girders due to reduced
weight the transportation and handling will be economical.
• Concrete structures are preferable for railway bridges to eliminate noise and
vibration problems and minimize the maintenance cost.
• In the construction of the concrete bridges and highway structures a general
requirement of using a water-binder ratio of less than 0.40 combined with the
use of silica fume so as to improve the chloride resistance against de-icing agents
and marine environment is recommended. This process improvement will
provide the advantages of reduced weight, increased strength and enhanced
durability

High-strength concrete is often used in bridges

• High-rise Buildings
• The reasons for using the high strength concrete in the area of high-rise
buildings are to reduce the dead load, the deflection, the vibration and the noise,
and the maintenance cost.
• Miscellaneous Applications
• Fibre reinforced concrete has been used with and without conventional
reinforcement in many field applications. These include bridge deck overlays,
floor slabs, pavements and pavement overlays, refractories, hydraulic structures,
thin shells, rock slope stabilization, mine tunnel linings and many precast
products. The addition of steel fibres is known to improve most of the
mechanical properties of concrete, namely, its static and dynamic tensile
strengths, energy abrasion and toughness, and fatigue resistance. Hence proper
utilization of steel fibre reinforced concrete depends on the skill of the engineer.

High-performance concrete is often used in bridges and
tall buildings

Materials Used in High-Performance Concrete
Material Primary contribution/Desired property
Portland cement Cementing material/durability
Blended cement Cementing material/durability/high strength
Fly ash Cementing material/durability/high strength
Slag Cementing material/durability/high strength
Silica fume Cementing material/durability/high strength
Calcined clay Cementing material/durability/high strength
Metakaolin Cementing material/durability/high strength
Calcined shale Cementing material/durability/high strength

Super plasticizers Flow ability
High-range water reducers Reduce water to cement ratio
Hydration control admixtures Control setting
Retarders Control setting
Accelerators Accelerate setting
Corrosion inhibitors Control steel corrosion
Water reducers Reduce cement and water content
Shrinkage reducers Reduce shrinkage
ASR inhibitors Control alkali-silica reactivity
Polymer/latex modifiers Durability
Optimally graded aggregate Improve workability and reduce paste demand

ConcreteEnvironment Deterioration
Impact
Resistance
ConcreteEnvironment
Durable
Concrete
(HPC)
The required durability characteristics are governed by the application of
concrete and by conditions expected to be encountered at the time of
placement. These characteristics should be listed.

References
• Concrete Technology by: R.P. Rethaliya
• Concrete Technology by . M.S. Shetty
• Internet websites
• http://www.foundationsakc.org/

High Performance Concrete

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