Specialty Concrete - High End Value Materials

High-Value Concrete

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 ConcreteMaterial Primary Contribution/Desired

Property

Portland cement Cementing material / Durability

Blended cementCementing 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

High-Value Concrete

Materials Used in High- Performance ConcreteMaterial 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

High-Value Concrete

Selected Properties of High- Performance

ConcreteProperty 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 PenetrationAASHTO 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

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/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

May be achieved by —

High-Value Concrete

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 —

High-Value Concrete

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)

High-Value Concrete

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 —

High-Value Concrete

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 —

High-Value Concrete

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 —

High-Value Concrete

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

High-Value Concrete

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

Durability Issues That HPC Can Address

High-Value Concrete

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)

High-Durability ConcreteConfederation Bridge, Northumberland Strait, Confederation Bridge, Northumberland Strait, Prince Edward Island/New Brunswick, 1997Prince Edward Island/New Brunswick, 1997

High-Value Concrete

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

Self-consolidating concrete (SCC) also known as self-compacting concrete —flows and consolidates on its own

High-Value Concrete

Self-Consolidating Concrete

High-Value Concrete

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

SCC for Power Plant in Pennsylvania—Mix Proportions

High-Value Concrete

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

Property Unit 80 MPa RPCCompressive 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 <1 30

Freeze-thaw RDF 90 100

Carbonation mm 2 0

Abrasion 10-12 m2/s 275 1.2

High-Value Concrete

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

Raw Material ComponentsRaw Material Components

uctal

High-Value Concrete

What is the typical Ductal® mix ?

230 kg/m3

710 kg/m3

210 kg/m3

40 - 160 kg/m313 kg/m3

140 kg/m3

1020 kg/m3

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