Concrete is the most widely used construction material in world 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. HPC is an engineered concrete possessing the most desirable properties during fresh as well as hardened concrete stages. HPC is far superior to conventional cement concrete as the ingredients of HPC contribute most optimally and efficiently to the various properties.
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. 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 Committee on HPC includes the following six criteria for material selections, mixing, placing, and curing procedures for concrete.
(1) Ease of placement
(2) Long term mechanical properties
(3) Early-age strength
(5) Life in severe environments
(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