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.
2. High-Value Concrete
All concrete is high value!
Cost
of material (small)
Cost
of placement (significant)
Cost
of Replacement (HIGH)
3. High-Value Concrete
High value generally associated with HighPerformance
What is High-Performance?
High-Early
Strength Concrete
High-Strength
Concrete
High-Durability
Concrete
Self-Consolidating
Reactive
Concrete
Powder Concrete
4. Characteristics of HighPerformance Concretes
High early strength
High strength
High modulus of elasticity
High abrasion resistance
High durability and long life in
severe environments
Low permeability and diffusion
Resistance to chemical attack
5. Characteristics of HighPerformance Concretes
High resistance to frost and
deicer scaling damage
Toughness and impact
resistance
Volume stability
Ease of placement
Compaction without
segregation
Inhibition of bacterial and mold
growth
6. Materials Used in HighPerformance Concrete
Material
Portland cement
Primary Contribution/Desired Property
Cementing material / Durability
Blended cement
Fly ash / Slag / Silica fume
Calcined clay/ Metakaolin
Calcined shale
Superplasticizers
High-range water reducers
Hydration control admix.
Cementing material /
Durability /
High strength
Flowability
Reduce water-cement ratio
Control setting
7. Materials Used in HighPerformance Concrete
Material
Retarders
Primary contribution/Desired property
Control setting
Accelerators
Corrosion inhibitors
Water reducers
Shrinkage reducers
ASR inhibitors
Optimally graded aggr.
Accelerate setting
Control steel corrosion
Reduce cement and water content
Reduce shrinkage
Control alkali-silica activity
Improve workability/reduce paste
Polymer/latex modifiers
Durability
8. Selected Properties of HighPerformance Concrete
Property
Test Method
Criteria that may be specified
High Strength
ASTM C 39
70-140 MPa @ 28 to 91 days
H-E Comp. Strength
ASTM C 39
20-30 MPa @ 3-12 hrs or 1-3 days
H-E Flex. Strength
ASTM C 78
2-4 MPa @ 3-12 hrs or 1-3 days
Abrasion Resistance
ASTM C 944
0-1 mm depth of wear
Low Permeability
ASTM C 1202
500 to 2000 coulombs
Chloride Penetration
AASHTO T
259/260
Less than 0.07% Cl at 6 months
Low Absorption
ASTM C 642
2% to 5%
High Mod.of Elast.
ASTM C 469
More than 40 GPa
9. High-Early-Strength Concrete
High-early compressive strength
ASTM C 39 (AASHTO T 22)
20 to 28 MPa (3000 to 4000 psi)
at 3 to 12 hours or 1 to 3 days
High-early flexural strength
ASTM C 78 (AASHTO T 97)
2 to 4 MPa (300 to 600 psi)
at 3 to 12 hours or 1 to 3 days
10. High-Early-Strength Concrete
May be achieved by —
Type III or HE high-early-strength cement
High cement content 400 to 600 kg/m3
(675 to 1000 lb/yd3)
Low water-cementing materials ratio
(0.20 to 0.45 by mass)
Higher freshly mixed concrete temperature
Higher curing temperature
11. High-Early-Strength Concrete
May be achieved by —
Chemical admixtures
Silica fume (or other SCM)
Steam or autoclave curing
Insulation to retain heat of
hydration
Special rapid hardening
cements
13. High-Strength Concrete Materials
Aggregates —
9.5 - 12.5 mm (3/8 - 1/2 in.) nominal maximum size
gives optimum strength
Combining single sizes for required grading allows for
closer control and reduced variability in concrete
For 70 MPa and greater, the FM of the sand should be
2.8 – 3.2. (lower may give lower strengths and sticky
mixes)
14. High-Strength Concrete Materials
Supplementary Cementing Materials —
Fly ash, silica fume, or slag often mandatory
Dosage rate 5% to 20% or higher by mass of
cementing material.
High-Value Concrete
15. High-Strength Concrete Materials
Admixtures —
Use of water reducers, retarders, HRWRs, or
superplasticizers — mandatory in high-strength
concrete
Air-entraining admixtures not necessary or
desirable in protected high-strength concrete.
Air
is mandatory, where durability in a freezethaw environment is required (i.e.. bridges,
piers, parking structures)
Recent
studies:
w/cm
≥ 0.30—air required
w/cm
< 0.25—no air needed
16. High-Strength Concrete
Placing, Consolidation, and Curing
Delays in delivery and placing
must be eliminated
Consolidation very important to achieve strength
Slump generally 180 to 220 mm (7 to 9 in.)
Little if any bleeding—fog or evaporation
retarders have to be applied immediately after
strike off to minimize plastic shrinkage and
crusting
7 days moist curing
17. High-Durability Concrete
1970s and 1980s focus on — High-Strength HPC
Today focus on concretes with high durability in
severe environments resulting in structures with long
life — High-Durability HPC
18. High-Durability Concrete
Durability Issues That HPC Can Address
Abrasion Resistance
Blast Resistance
Permeability
Carbonation
Freeze-Thaw Resistance
Chemical Attack
Alkali-Silica Reactivity
Corrosion rates of rebar
20. Self-Consolidating Concrete
Self-consolidating concrete (SCC) also known as
self-compacting concrete —
flows and consolidates on its own
developed in 1980s — Japan
Increased amount of
Fine
material
(i.e. fly ash or limestone filler)
HRWR/Superplasticizers
Strength and durability same as
conventional concrete
27. What is the typical mix ?
Cement
710 kg/m3
230 kg/m3
210 kg/m3
1020 kg/m3
Silica fume
Crushed
Quartz
Sand
Fibres
kg/m3
40 - 160
13 kg/m3
140 kg/m3
High-Value Concrete
Superplasticizer
Total water
28. What is the typical mix ?
Cement
28 - 30%
Silica fume
9 – 10%
Crushed
Quartz
8.5 – 9%
Sand
42 –43%
Fibres
Superplasticizer
1.7 – 6.5%
0.6%
5.5 – 6%
Total water
w/c = 0.20
No aggregates !
29. Conclusion
High Value concrete 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.