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Specialty%20Concrete%20-%20High%20End%20Value%20Materials

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Title: Specialty%20Concrete%20-%20High%20End%20Value%20Materials


1
Specialty Concrete - High End Value Materials
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
    High-Performance
  • What is High-Performance?
  • High-Early Strength Concrete
  • High-Strength Concrete
  • High-Durability Concrete
  • Self-Consolidating Concrete
  • Reactive Powder Concrete

4
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

5
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

6
Materials Used in High- Performance
Concrete
Material Primary Contribution/Desired Property
Portland cement Cementing material / Durability
Blended cement Cementing material / Durability / High strength
Fly ash / Slag / Silica fume Cementing material / Durability / High strength
Calcined clay/ Metakaolin Cementing material / Durability / High strength
Calcined shale Cementing material / Durability / High strength
Superplasticizers Flowability
High-range water reducers Reduce water-cement ratio
Hydration control admix. Control setting
7
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
8
Selected Properties of High- Performance
Concrete
Property Test Method Criteria that may be specified
High Strength ASTM C 39 70-140 MPa _at_ 28 to 91 days
H-E Comp. Strength ASTM C 39 20-30 MPa _at_ 3-12 hrs or 1-3 days
H-E Flex. Strength ASTM C 78 2-4 MPa _at_ 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
  • 2 to 5

ASTM C 642
ASTM C 469
High Mod.of Elast.
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

12
High-Strength Concrete
  • 90 of ready-mix concrete
  • 20 MPa - 40 MPa (3000 6000 psi) _at_ 28-d (most
    30 MPa 35 MPa)
  • High-strength concrete by definition
  • 28 day compr. strength
  • ? 70 MPa (10,000 psi)

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.

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
    freeze-thaw environment is required (i.e..
    bridges, piers, parking structures)
  • Recent studies
  • w/cm 0.30air required
  • w/cm lt 0.25no 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 bleedingfog 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

19
High-Durability Concrete
Confederation Bridge, Northumberland Strait,
Prince Edward Island/New Brunswick, 1997
  • Cement 398 kg/m3 (671 lb/yd3)
  • Fly ash 45 kg/m3 (76 lb/yd3)
  • Silica fume 32 kg/m3 (72 lb/yd3)
  • w/c 0.30
  • Water Red. 1.7 L/m3 (47 oz/yd3)
  • HRWR 15.7 L/m3 (83 oz/yd3)
  • Air 5-8
  • 91d strength 60 MPa (8700 psi)

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

21
Self-Consolidating Concrete
22
SCC for Power Plant in PennsylvaniaMix
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
23
Reactive-Powder Concrete (RPC)
  • Properties
  • High strength 200 MPa (can be produced to 810
    MPa)
  • Very low porosity
  • Properties are achieved by
  • Max. particle size ? 300 ?m
  • Optimized particle packing
  • Low water content
  • Steel fibers
  • Heat-treatment

24
Mechanical Properties of RPC
Property Unit 80 MPa RPC
Compressive strength MPa (psi) 80 (11,600) 200 (29,000)
Flexural strength MPa (psi) 7 (1000) 40 (5800)
Tensile strength MPa (psi) 8 (1160)
Modulus of Elasticity GPa (psi) 40 (5.8 x 106) 60 (8.7 x 106)
Fracture Toughness 103 J/m2 lt1 30
Freeze-thaw RDF 90 100
Carbonation mm 2 0
Abrasion 10-12 m2/s 275 1.2
25
Reactive Powder Concrete
26
Raw Material Components
  • Cement
  • Sand
  • Silica quartz
  • Silica fume
  • Micro-Fibres - metallic or poly-vinyl acetate
  • Mineral fillers - Nano-fibres
  • Superplasticizer
  • Water

27

uctal
What is the typical Ductal mix ?
Cement
710 kg/m3
Silica fume
230 kg/m3
Crushed Quartz
210 kg/m3
Sand
1020 kg/m3
Fibres
Superplasticizer
40 - 160 kg/m3
13 kg/m3
Total water
140 kg/m3
No aggregates !
28

uctal
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
Total water
0.6
5.5 6
No aggregates !
w/c 0.20
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