High-strength concrete and high-performance concrete are not synonymous because strength and performance of concrete are different properties of concrete. High-strength concrete is defined based on its compressive strength at a given age whereas high-performance concrete is defined based on performance criteria namely: high durability, high strength, and high workability.
High-performance concrete is defined as a concrete that meets special combination of performance and uniformity requirements that cannot always be achieved routinely using conventional constituents and normal mixing, placing, and curing practice. However, high strength concrete is defined as concrete that has a compressive strength of 55MPa or higher, as per ACI Code.
The use of high-performance concrete has overcome many problems observed in conventional concrete like less durability, weaker transition zone (aggregate-cement interface), low resistance to chemical attack and difficulty in repair and retrofitting works. High strength concrete has been used in the construction of many structures to decrease the size of members, reduce dead load, and decline cost and construction materials.
Table 1 Difference between High-Performance Concrete and High Strength Concrete
|Items||High-Performance Concrete||High-Strength Concrete|
|Definition||High-performance concrete is defined 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, as per ACI Code.||High strength concrete is defined as concrete that has compressive of 55 MPa or greater.|
|Types||Chemical resistant concrete, early drying concrete, ultra-water resistant concrete, heat resistant concrete, and impact and abrasion resistant concrete.||High-Strength Concrete (50 – 100 MPa), ultra-High Strength Concrete (100 – 150 MPa), especial Concrete (> 150 MPa)|
|Strength criteria||High strength, modulus of elastic, low creep and shrinkage||It has high strength but does not necessarily possess superior characteristic as high-performance concrete|
|Durability criteria||Resist scaling, freezing and thawing, chloride and carbonation, and prohibit bacterial and mold growth||Durability of high strength is commonly improved by adding pozzolanic materials|
|Ductility||Low ductility but can be improved by adding steel fibers||It is brittle|
|Compositions||Cement, fine aggregate, coarse aggregate, water, mineral admixtures; fine filler and/or pozzolanic supplementary cementation materials, chemical admixtures; plasticizers, superplasticizers, retarders, air-entraining agents)||Cement, fine and coarse aggregate; fine aggregates with higher fineness modulus of around 3 is recommended, water, water reducing admixtures|
|Degree of quality control requirements||It is sensitive to changes in constituent material properties, hence great degree of quality control is required for the successful production of high-performance concrete.||High quality control is needed in order to maintain the special properties desired.|
|Production of concrete||High-performance concrete is produced by careful selection of raw materials such chemical admixtures and appropriate mix design to achieve the desired performance objectives.||High-strength concrete is achieved at low water to cement ratio which is obtained by adding water reducing plasticizer or high range water reducing plasticizer. It is also essential to select a high-quality Portland cement, and optimize aggregates, then optimize the combination of materials by varying the proportions of cement, water, aggregates, and admixtures.|
|Placement and compaction||Easy to pour and can be compacted without segregation.||Placement would not be easy unless superplasticizer is used|
|Advantages||For advantage of high-performance concrete please click here.||Reduce maintenance and repair, decline size of members and cost of formworks, allow longer spans in bridge and hence decrease number of vertical supports, and permits construction of thinner slabs.|
|Disadvantages||Need extensive quality control, costly, need special constituents, and need to be manufactured and placed careful.||Low resistance to fire i.e. damage at high temperature, and need great expertise in selection of constituents.|
|Applications||For applications of high-performance concrete please click here.||High rise buildings, bridges with long spans, and high load carrying buildings built on weak soil.|