Transcript High-Performance Concrete

Specialty Concrete High End Value Materials
High-Value Concrete
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High-Value
Concrete
All concrete is high value!
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Cost of material (small)
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Cost of placement (significant)
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Cost of Replacement (HIGH)
High-Value Concrete
High-Value
Concrete
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High value generally associated
with High-Performance
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What is High-Performance?
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High-Early Strength Concrete
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High-Strength Concrete
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High-Durability Concrete
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Self-Consolidating Concrete
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Reactive Powder Concrete
Characteristics of HighPerformance Concretes
High-Value
Concrete
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High early strength
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High strength
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High modulus of elasticity
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High abrasion resistance
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High durability and long life in
severe environments
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Low permeability and diffusion
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Resistance to chemical attack
Characteristics of HighPerformance Concretes
High-Value
Concrete
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High resistance to frost and
deicer scaling damage
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Toughness and impact
resistance
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Volume stability
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Ease of placement
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Compaction without
segregation
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Inhibition of bacterial and
mold growth
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.
High-Value
Concrete
Cementing material /
Durability /
High strength
Flowability
Reduce water-cement ratio
Control setting
Materials Used in HighPerformance Concrete
Material
Retarders
Accelerators
Corrosion inhibitors
Water reducers
Primary contribution/Desired property
Control setting
Accelerate setting
Control steel corrosion
Reduce cement and water content
Shrinkage reducers
ASR inhibitors
Optimally graded aggr.
Reduce shrinkage
Control alkali-silica activity
Improve workability/reduce paste
Polymer/latex modifiers
Durability
High-Value
Concrete
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
High-Value
Concrete
High-Early-Strength
Concrete
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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
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High-Value
Concrete
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
High-Early-Strength
Concrete
May be achieved by —
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High-Value
Concrete
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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
High-Early-Strength
Concrete
May be achieved by —
High-Value
Concrete
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Chemical admixtures
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Silica fume (or other SCM)
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Steam or autoclave curing
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Insulation to retain heat of
hydration
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Special rapid hardening cements
High-Strength Concrete
High-Value
Concrete
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90% of ready-mix concrete
20 MPa - 40 MPa (3000 –
6000 psi) @ 28-d
(most 30 MPa – 35 MPa)
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High-strength concrete
by definition —
28 day – compr. strength
 70 MPa (10,000 psi)
High-Strength Concrete Materials
Aggregates —
High-Value
Concrete
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9.5 - 12.5 mm (3/8 - 1/2 in.) nominal
maximum size gives optimum
strength
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Combining single sizes for required
grading allows for closer control and
reduced variability in concrete
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For 70 MPa and greater, the FM of
the sand should be 2.8 – 3.2. (lower
may give lower strengths and sticky
mixes)
High-Strength Concrete Materials
Supplementary Cementing Materials —
High-Value
Concrete
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Fly ash, silica fume, or slag often
mandatory
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Dosage rate 5% to 20% or higher
by mass of cementing material.
High-Strength Concrete Materials
Admixtures —
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Use of water reducers, retarders,
HRWRs, or superplasticizers —
mandatory in high-strength concrete
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Air-entraining admixtures not necessary
or desirable in protected high-strength
concrete.
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Air is mandatory, where durability in a
freeze-thaw environment is required (i.e..
bridges, piers, parking structures)
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Recent studies:
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High-Value
Concrete
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w/cm ≥ 0.30—air required
w/cm < 0.25—no air needed
High-Strength Concrete
Placing, Consolidation, and Curing
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High-Value
Concrete
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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
High-Durability Concrete
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High-Value
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
High-Durability Concrete
Durability Issues That HPC Can Address
High-Value
Concrete
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Abrasion Resistance
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Blast Resistance
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Permeability
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Carbonation
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Freeze-Thaw Resistance
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Chemical Attack
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Alkali-Silica Reactivity
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Corrosion rates of rebar
High-Durability Concrete
Confederation Bridge, Northumberland Strait,
Prince Edward Island/New Brunswick, 1997
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High-Value
Concrete
Cement:
Fly ash:
Silica fume:
w/c:
Water Red.:
HRWR:
Air:
91d strength:
398 kg/m3
45 kg/m3
32 kg/m3
0.30
1.7 L/m3
15.7 L/m3
5-8%
60 MPa
(671 lb/yd3)
(76 lb/yd3)
(72 lb/yd3)
(47 oz/yd3)
(83 oz/yd3)
(8700 psi)
Self-Consolidating Concrete
Self-consolidating concrete (SCC) also
known as self-compacting concrete —
flows and consolidates on its own
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developed in 1980s — Japan
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Increased amount of
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High-Value
Concrete
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Fine material
(i.e. fly ash or limestone filler)
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HRWR/Superplasticizers
Strength and durability same as
conventional concrete
Self-Consolidating Concrete
High-Value
Concrete
SCC for Power Plant in
Pennsylvania—Mix Proportions
Portland cement (Type I)
297 kg/m3
(500 lb/yd3)
Slag cement
128 kg/m3
(215 lb/yd3)
Coarse aggregate
675 kg/m3
(1,137 lb/yd3)
Fine aggregate
1,026 kg/m3 (1,729 lb/yd3)
Water
170 kg/m3
(286 lb/yd3)
Superplasticizer ASTM C 494, Type F
(Polycarboxylate-based) 1.3 L/m3
(35 oz/yd3)
AE admixture as needed for 6% ± 1.5% air content
High-Value
Concrete
Reactive-Powder Concrete (RPC)
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Properties:
High strength — 200 MPa
(can be produced to 810 MPa)
 Very low porosity
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Properties are achieved by:
Max. particle size  300 m
 Optimized particle packing
 Low water content
 Steel fibers
 Heat-treatment
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High-Value
Concrete
Mechanical Properties of RPC
Property
Compressive
strength
Flexural strength
Tensile strength
Modulus of Elasticity
Fracture Toughness
Freeze-thaw
Carbonation
Abrasion
High-Value
Concrete
Unit
80 MPa
RPC
MPa (psi)
80 (11,600)
200 (29,000)
MPa (psi)
MPa (psi)
7 (1000)
40 (5800)
8 (1160)
GPa (psi) 40 (5.8 x 106) 60 (8.7 x 106)
103 J/m2
<1
30
RDF
90
100
mm
10-12 m2/s
2
275
0
1.2
Reactive Powder Concrete
High-Value
Concrete
uctal
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Raw Material
Components
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High-Value
Concrete
Cement
Sand
Silica quartz
Silica fume
Micro-Fibres - metallic or poly-vinyl acetate
Mineral fillers - Nano-fibres
Superplasticizer
Water
uctal
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What is the typical Ductal® 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
No aggregates !
uctal
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What is the typical Ductal® 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%
High-Value
Concrete
Total water
w/c = 0.20
No aggregates !