High performance concrete

Post on 16-Jul-2015

128 views 3 download

Tags:

Transcript of High performance concrete

Mehta and Aitcinsuggested the term high performance concrete (HPC) for concrete mixtures that possess the following three properties: high-workability, high-strength, and high durability.

American Concrete Institute defines High Performance Concrete as

“A concrete which meets special performance and uniformity requirements that cannot be achieved by routine conventional concrete.”

Compressive Strength(N/mm2) High Performance Concrete Class

50 I

75 II

100 III

125 IV

150 V

Cement

Fine Aggregate

Coarse Aggregate

Water

Mineral Admixtures such as

Fly ash

Silica fume

Ground granulated blast furnace slag

Chemical Admixtures such as Superplasticizers

Cement containing as little C3A as possible

Cement should be finely ground and contain fair amount of C3S

Sand or crushed stones may be used.

Having minimum void ratio.

Strength of HPC is controlled by strength of coarse aggregate.

Hence selection of coarse

aggregate would be an

important step in

HPC design mix.

Requirement of water should be reduced to the required quantity.

Increase in the speed of construction.

High workability and pump ability.

Improved Durability in aggressive and marine environment.

Service life more than 100 years.

Higher initial cost and reduced maintenance cost.

Low shrinkage and high strength.

Manufactured and placed much more carefully.

Extended Quality Control is required.

Very Early Strength (14 MPa in 6 hours),

High Early Strength (34 MPa in 24 hours),

Very High Strength (69 MPa in 28 days),

High Early Strength with Fiber-reinforcement.

HPC is being extensively used now for the

fabrication of precast pylons, piers, and girders of

many long span bridges in the world: