High Performance concrete

1. Group assignment
Project: Preliminary design a sustainable and durable concrete using synergistic
effects of SCMs for a high rise building.
Group Members:
L163330115, L163330118, L163330108, L163330113, L163330116,
L163330119, L163330103, L163330114, L163330120

2. Characteristics of High-Performance 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

3. Characteristics of High-Performance 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

4. Material Primary Contribution/Desired Property
Portland cement Cementing material / Durability
Blended cement
Cementing material /
Durability /
High strength
Fly ash / Slag / Silica fume
Calcined clay/ Metakaolin
Calcined shale
Superplasticizers Flowability
High-range water reducers Reduce water-cement ratio
Hydration control admix. Control setting
Materials Used in High-Performance Concrete

5. High-Value Concrete
Materials Used in High-Performance Concrete
Material Primary contribution/Desired property
Retarders Control setting
Accelerators Accelerate setting
Corrosion inhibitors Control steel corrosion
Water reducers Reduce cement and water content
Shrinkage reducers Reduce shrinkage
ASR inhibitors Control alkali-silica activity
Improve workability/reduce paste
Polymer/latex modifiers
Optimally graded aggr.
Durability

6. Selected Properties of High-Performance 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

7. 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

8. High-Early-Strength Concrete
• Type III or HE high-early-strength cement
• High cement content 400 to 600 kg/m3
• Low water-cementing materials ratio (0.20 to 0.45 by mass)
• Higher freshly mixed concrete temperature
• Higher curing temperature
May be achieved by —

9. High-Early-Strength Concrete
• Chemical admixtures
• Silica fume (or other SCM)
• Steam or autoclave curing
• Insulation to retain heat of hydration
• Special rapid hardening cements
May be achieved by —

10. High-Strength Concrete
 90% of ready-mix concrete
20 MPa - 40 MPa (3000 –
6000 psi) @ 28-d
(most 30 MPa – 35 MPa)
 High-strength concrete
by definition —
28 day – compr. strength
 70 MPa (10,000 psi)

11. High-Strength Concrete Materials
• 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).
Aggregates —

12. High-Strength Concrete Materials
• Fly ash, silica fume, or slag often mandatory;
• Dosage rate 5% to 20% or higher by mass of cementing material.
Supplementary Cementing Materials —

13. High-Strength Concrete Materials
• 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 freeze-thaw environment is
required (i.e.. bridges, piers, parking structures)
• Recent studies:
• w/cm ≥ 0.30—air required
• w/cm < 0.25—no air needed
Admixtures —

14. High-Strength Concrete
• 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.
Placing, Consolidation, and Curing

15. What is the best mix ?
9 – 10%
28 - 30%
8.5 – 9%
1.7 – 6.5%
0.6%
5.5 – 6%
42 –43%
Cement
Silica fume
Crushed
Quartz
Sand
Fibres
Superplasticizer
Total water
No aggregates !

w/c = 0.20

16. What is the typical mix ?
230 kg/m3
710 kg/m3
210 kg/m3
40 - 160 kg/m3
13 kg/m3
140 kg/m3
1020 kg/m3
Cement
Silica fume
Crushed
Quartz
Sand
Fibres
Superplasticizer
Total water
No aggregates !
