It is concrete mix which posses high workability, high strength, high elasticity,high density,low permeability.

A substantial reduction of quantity of mixing water is fundamental step for making HPC. Silica fume improve the qualities of transition zone thereby increasing strength up to 80MPA and above.

Appropriate superplastisizer can achieve W/C ratio in the range of 0.25 to 0.3 and high slump. In India HPC of strength 60MPA was used for first time for construction of containment dome at Kaiga and Rajsthan atomic power projects.

Properties of high performance concrete

1) Very careful gradating of aggregate is required.

2) Re vibration and pressure compaction is used.

3) Compressive strength is more than 50MPa.

$\quad$ i.e grade higher than M50 and upto M70
$\quad$ i.e 70 $N/mm^2$ or MPa compressive strength for 28 days test.

Advantages

1) Very high compressive strength.

2) Special construction made possible.

3) Useful for specialized structure like atomic power station, satelight launching station, modern dam heavy duty runway etc.

Disadvantages

1) High cost

2) Special equipment may be needed

3) Expertise needed.