this ppt is related to civil engineer in concrete field

2. High performance concrete (HPC) has been in use for quite
sometimes in the developed countries.In India, till the last
decade,HPC meant only High Strength Concrete. Experience has
shown that besides strength,there are other equally important
criteria such as durability,workability, toughness.
HPC invariably contains in addition to high quality OPC, one
or more cementitious materials such as fly ash and silica fume and
a superplasticizer.
The main purpose of developing HPC is to enhance the life of
structure. Durability becomes a paramount factor in development
and application of HPC.

3. 1.Workability:-
HPC should have sufficient workability for proper placing and
compaction. As water-cement ratios used in HPC are very low (of
the order of 0.3) the use of super plasticizer becomes essential in
obtaining the required workability.
2.Strength:-
As mentioned earlier, the strength of HPC is invariably higher
than the normal mixes. It can range anywhere between 60 Mpa and
150 Mpa (28 days strength).

4. 3.Impermeability:-
HPC has to be highly impermeable in order to prevent
the ingress of moisture and ions of harmful chemicals.
Primarily, three factors influence the permeability of concrete.
They are: water-cement ratio, compaction and curing.
Water-cement ratio:-
As the water-cement ratio reduces, concrete becomes
more impermeable. Additionally, certain mineral admixtures
also improve impermeability of concrete.

5.  Compaction:-
Proper compaction is essential even in case of flowing
concrete in order to improve pockets of entrapped air and
obtain a uniform distribution of coarse aggregate and water.
In general, better the compaction is, more impermeable the
resulting concrete will be.
 Curing:-
As is well known, proper curing of concrete is necessary
for gain of required strength and to achieve impermeability.

6. 4. Dimensional Stability:-
Higher elastic modulus, low drying shrinkage, creep and
low thermal strain are some of the key factors contributing to high
dimensional stability of HPC. This is very essential for
counteracting any undesirable effects produced as a result of
volume changes under conditions of restraint. Compared to 20 to
25Gpa elastic modulus for conventional concrete, it is possible to
obtain 40 to 45Gpa elastic modulus for HPC.

7. 1.High performance concrete, when the strength range is 50-
100Mpa
2.Very high performance concrete , when the strength range is
100-150 Mpa
3.Hyper performance concrete , when the strength range is more
than 150Mpa

8.  Cement:
 Aggregate:
 Mineral Admixtures:-
 Water Reducing Agents (Super plasticizers):

9.  To improve the strength and other properties, it is
necessary to strengthen weak areas. Reducing the water-
cement ratio and using supplementary cementations'
material like silica fume tends to strengthen the
transition zone.
 When Portland cement hydrates, a considerable quantity
of calcium hydroxide is produced, typically 22-24%.
Silica fume which has a very high percentage (over 85%)
of amorphous silica dioxide, reacts with calcium
hydroxides to form calcium silicate hydrate.

10.  Increase the amount of cement
 Decrease water
 Doing both at the same time

11.  Economy
 Small cross-sections
 Slender members
 Extended service life
 Reduction in weight
 Reduced beam depth
 Low creep, shrinkage

12.  The concreted member needs to be protected from
the weather, immediately after the placement and
vibration.
 This is easily realized by covering the exposed
surface with the plastic sheets progressively as
concreting proceeds and of moist curing within a
few hours

13.  Water Tower Place (Chicago, 1975):- It typifies
composition of HPC prior to the use of plasticizer.
 Jingly Bridge (France, 1989):- It was constructed
using HPC without silica fume, this was done to
demonstrate that HPC can be produced and used in
construction even when silica flume is not economically
available.
 Scotia Plaza (Toronto, 1987):- It was built using HPC
containing both silica fume and blast-furnace slag.

14.  As with any concrete the compressive strength of HPC
depends on water-cement ratio but the strength of the
aggregate itself can be a limiting factor.
 For the first time in the history of concrete technology
workable concrete can be made with a water content in
the mixture no greater than the amount of water
theoretically required to hydrate all the cement present.
This is possible because of outstanding dispersing
properties of modern super plasticizers.

15.  Neville on Concrete, A.M. Neville
 Indian Concrete Journal
 Properties of Concrete, A.M. Neville
 Concrete Technology, M.S. Shetty