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Extreme Concrete

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High-end construction concrete

High-end construction concrete

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  • EB001 –Design and Control of Concrete Mixtures—14 th Edition, 2002, Chapter 17, pages 299 to 314.
  • Fig. 17-1. High-performance concrete is often used in bridges. (70017)
  • Fig. 17-1. High-performance concrete is often used in tall buildings. (70023)
  • Table 17-1. Materials Used in High-Performance Concrete
  • Table 17-1. Materials Used in High-Performance Concrete
  • Table 17-2. Selected Properties of High-Performance Concrete
  • High-early-strength can be obtained by using one or a combination of the following, depending on the age at which the specified strength must be achieved and on job conditions.
  • High-early-strength can be obtained by using one or a combination of the following, depending on the age at which the specified strength must be achieved and on job conditions.
  • Explosive nature of high-strength concrete upon failure when tested in compression. (53272)
  • The Confederation Bridge across the Northumberland Strait between Prince Edward Island and New Brunswick has a 100-year design life. This bridge contains HPC designed to efficiently protect the embedded reinforcement. The concrete had a diffusion coefficient of 4.8 x 10-13 at six months (a value 10 to 30 times lower than that of conventional concrete). The electrical resistivity was measured at 470 to 530 ohm-m, compared to 50 for conventional concrete. The design required that the concrete be rated at less than 1000 coulombs. The high concrete resistivity in itself will result in a rate of corrosion that is potentially less than 10 percent of the corrosion rate for conventional concrete
  • Total content of particles finer than 160 μm sieve has to be high (usually 520 – 560 kg/m 3 ) HRWRs based on polycarboxylate ethers typically used to plasticize the mix. Very sensitive to fluctuation in water content therefore stabilizers such as polysaccarides are used
  • Fig. 17-6. Examples of materials used in regular concrete and self-compacting concrete by absolute volume.
  • Project: Seward Power Plant, New Florence, Pa.
  • Fig. 17-8. Freshly-mixed reactive-powder concrete.
  • Table 17-6. Typical Mechanical Properties of Reactive Powder Concrete (RPC) compared to an 80-MPa Concrete (Perry 1998).
  • Fig. 17-9. The Sherbrooke footbridge in Quebec, built in 1997, is North America’s first reactive-powder concrete structure. (68300)

Extreme Concrete Extreme Concrete Presentation Transcript

  • Specialty Concrete - High End Value Materials
  • High-Value Concrete
    • All concrete is high value!
      • Cost of material (small)
      • Cost of placement (significant)
      • Cost of Replacement (HIGH)
    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
    High-Value Concrete High-Value Concrete
  • 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
    High-Value Concrete
  • 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
    High-Value Concrete
  • Materials Used in High- Performance Concrete High-Value Concrete 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 High-Value Concrete Optimally graded aggr. Durability 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
  • Selected Properties of High- Performance Concrete
    • 2% to 5%
    High-Value Concrete Low Absorption ASTM C 642 High Mod.of Elast. ASTM C 469 More than 40 GPa 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
  • 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
    High-Value Concrete
  • High-Early-Strength Concrete
    • Type III or HE high-early-strength cement
    • High cement content 400 to 600 kg/m 3 (675 to 1000 lb/yd 3 )
    • Low water-cementing materials ratio (0.20 to 0.45 by mass)
    • Higher freshly mixed concrete temperature
    • Higher curing temperature
    High-Value Concrete May be achieved by —
  • 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
    High-Value Concrete May be achieved by —
  • High-Strength Concrete High-Value 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)
  • 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)
    High-Value Concrete Aggregates —
  • High-Strength Concrete Materials
    • Fly ash, silica fume, or slag often mandatory
    • Dosage rate 5% to 20% or higher by mass of cementing material.
    High-Value Concrete Supplementary Cementing Materials —
  • 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
    High-Value Concrete Admixtures —
  • 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
    High-Value Concrete Placing, Consolidation, and Curing
  • 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
    High-Value Concrete
  • High-Durability Concrete
    • Abrasion Resistance
    • Blast Resistance
    • Permeability
    • Carbonation
    • Freeze-Thaw Resistance
    • Chemical Attack
    • Alkali-Silica Reactivity
    • Corrosion rates of rebar
    High-Value Concrete Durability Issues That HPC Can Address
    • Cement: 398 kg/m 3 (671 lb/yd 3 )
    • Fly ash: 45 kg/m 3 (76 lb/yd 3 )
    • Silica fume: 32 kg/m 3 (72 lb/yd 3 )
    • w/c: 0.30
    • Water Red.: 1.7 L/m 3 (47 oz/yd 3 )
    • HRWR: 15.7 L/m 3 (83 oz/yd 3 )
    • Air: 5-8%
    • 91d strength: 60 MPa (8700 psi)
    High-Durability Concrete High-Value Concrete Confederation Bridge, Northumberland Strait, Prince Edward Island/New Brunswick, 1997
  • Self-Consolidating Concrete
    • 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
    High-Value Concrete Self-consolidating concrete (SCC) also known as self-compacting concrete — flows and consolidates on its own
  • Self-Consolidating Concrete High-Value Concrete
  • SCC for Power Plant in Pennsylvania—Mix Proportions High-Value Concrete Portland cement (Type I) 297 kg/m 3 (500 lb/yd 3 ) Slag cement 128 kg/m 3 (215 lb/yd 3 ) Coarse aggregate 675 kg/m 3 (1,137 lb/yd 3 ) Fine aggregate 1,026 kg/m 3 (1,729 lb/yd 3 ) Water 170 kg/m 3 (286 lb/yd 3 ) Superplasticizer ASTM C 494, Type F (Polycarboxylate-based) 1.3 L/m 3 (35 oz/yd 3 ) AE admixture as needed for 6% ± 1.5% air content
  • 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
    High-Value Concrete
  • Mechanical Properties of RPC High-Value Concrete 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 10 6 ) 60 (8.7 x 10 6 ) Fracture Toughness 103 J/m 2 <1 30 Freeze-thaw RDF 90 100 Carbonation mm 2 0 Abrasion 10 -12 m 2 /s 275 1.2
  • Reactive Powder Concrete High-Value Concrete
    • Cement
    • Sand
    • Silica quartz
    • Silica fume
    • Micro-Fibres - metallic or poly-vinyl acetate
    • Mineral fillers - Nano-fibres
    • Superplasticizer
    • Water
    High-Value Concrete Raw Material Components uctal
  • High-Value Concrete What is the typical Ductal ® mix ?
      • 230 kg/m 3
      • 710 kg/m 3
      • 210 kg/m 3
      • 40 - 160 kg/m 3
      • 13 kg/m 3
      • 140 kg/m 3
      • 1020 kg/m 3
    Cement Silica fume Crushed Quartz Sand Fibres Superplasticizer Total water No aggregates ! uctal
  • High-Value Concrete What is the typical Ductal ® 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 ! uctal w/c = 0.20