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The American Concrete Institute (ACI) defines high-performance concrete as concrete meeting special combinations of performance and uniformity requirements that cannot always be achieved routinely when using conventional constituents and normal mixing, placing and curing practices. A commentary to the definition states that a high-performance concrete is one in which certain characteristics are developed for a particular application and environment.
Examples of characteristics that may be considered critical for an application are:
* Ease of placement
* Compaction without segregation
* Early age strength
* Long-term mechanical properties
* Permeability
* Density
* Heat of hydration
* Toughness
* Volume stability
* Long life in severe environments
1- Reducing the water quantity from the concrete mix and add plastizer admixture
2- We can replace some amount of cement and add GGBS andsilica fume
3- We should select a good material for the mix (Sand, well graded Aggregate, and cement)
4- we should care about vibration while casting
5- We should care about curing after casting
The conventional Portland cement concrete is found deficient in respect of : ·
Durability in severe environs (shorter service life and frequent maintenance)
Time of construction (slower gain of strength)
Energy absorption capacity (for earthquake resistant structures)
Repair and retrofitting jobs.
Hence it has been increasingly realized that besides strength, there are other equally important criteria such as durability, workability and toughness.
‘High performance concrete’ performance requirements can be different than high strength and can vary from application to application.
Minimum cement / cementious content
Compressive and tensile strength
Aggregate curves for mix design
Percentage of chemical admixtures
Water content
Sulfate exposure
Standard tests ( slump, temperature, destructive ) and Quality control per specs and codes
Excellent workmanship ( placing, finishing, curing ) to provide long term durability
American Concrete Institute (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.
The Strategic Highway Research Programme (SHRP) has defined HPC for highway application on the following strength, durability, and w/c ratio criteria.
(a) It should satisfy one of the following strength criteria: 4 hour strength ≥17.5 Mpa 24 hour strength ≥35.0 Mpa 28 days strength ≥ 70.0 Mpa
(b) It should have a durability factor greater than 80% after 300 cycles of freezing and thawing.
(c) It should have a water-cement ratio of 0.35 or less.
1) proper mix design to suit the best workability
2) Ensure workmanship while pouring
Concrete strength grade, mix ratio, mix design, compactiblity e.t.c
(a) It should satisfy one of the following strength criteria: 4 hour strength ≥17.5 Mpa 24 hour strength ≥35.0 Mpa 28 days strength ≥ 70.0 Mpa
(b) It should have a durability factor greater than 80% after 300 cycles of freezing and thawing.
(c) It should have a water-cement ratio of 0.35 or less.
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