Presentation is loading. Please wait.

Presentation is loading. Please wait.

Specialty Concrete - High End Value Materials. High-Value Concrete n All concrete is high value! u Cost of material (small) u Cost of placement (significant)

Similar presentations


Presentation on theme: "Specialty Concrete - High End Value Materials. High-Value Concrete n All concrete is high value! u Cost of material (small) u Cost of placement (significant)"— Presentation transcript:

1 Specialty Concrete - High End Value Materials

2 High-Value Concrete n All concrete is high value! u Cost of material (small) u Cost of placement (significant) u Cost of Replacement (HIGH)

3 High-Value Concrete n High value generally associated with High-Performance n What is High-Performance? u High-Early Strength Concrete u High-Strength Concrete u High-Durability Concrete u Self-Consolidating Concrete u Reactive Powder Concrete High-Value Concrete

4 Characteristics of High- Performance Concretes n High early strength n High strength n High modulus of elasticity n High abrasion resistance n High durability and long life in severe environments n Low permeability and diffusion n Resistance to chemical attack

5 High-Value Concrete Characteristics of High- Performance Concretes n High resistance to frost and deicer scaling damage n Toughness and impact resistance n Volume stability n Ease of placement n Compaction without segregation n Inhibition of bacterial and mold growth

6 High-Value Concrete Materials Used in High- Performance Concrete MaterialPrimary Contribution/Desired Property Portland cementCementing material / Durability Blended cement Cementing material / Durability / High strength Fly ash / Slag / Silica fume Calcined clay/ Metakaolin Calcined shale SuperplasticizersFlowability High-range water reducersReduce water-cement ratio Hydration control admix.Control setting

7 High-Value Concrete Materials Used in High- Performance Concrete MaterialPrimary contribution/Desired property RetardersControl setting AcceleratorsAccelerate setting Corrosion inhibitorsControl steel corrosion Water reducersReduce cement and water content Shrinkage reducersReduce shrinkage ASR inhibitorsControl alkali-silica activity Improve workability/reduce paste Polymer/latex modifiers Optimally graded aggr. Durability

8 High-Value Concrete Selected Properties of High- Performance Concrete PropertyTest MethodCriteria that may be specified High StrengthASTM C to 91 days H-E Comp. StrengthASTM C hrs or 1-3 days H-E Flex. StrengthASTM C hrs or 1-3 days Abrasion ResistanceASTM C mm depth of wear Low PermeabilityASTM C 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

9 High-Value Concrete High-Early-Strength Concrete n 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 n 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-Value Concrete High-Early-Strength Concrete n Type III or HE high-early-strength cement n High cement content 400 to 600 kg/m 3 (675 to 1000 lb/yd 3 ) n Low water-cementing materials ratio (0.20 to 0.45 by mass) n Higher freshly mixed concrete temperature n Higher curing temperature May be achieved by —

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

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

13 High-Value Concrete High-Strength Concrete Materials n mm (3/8 - 1/2 in.) nominal maximum size gives optimum strength n Combining single sizes for required grading allows for closer control and reduced variability in concrete n 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 —

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

15 High-Value Concrete High-Strength Concrete Materials n Use of water reducers, retarders, HRWRs, or superplasticizers — mandatory in high-strength concrete n Air-entraining admixtures not necessary or desirable in protected high-strength concrete. u Air is mandatory, where durability in a freeze-thaw environment is required (i.e.. bridges, piers, parking structures) u Recent studies: H w/cm ≥ 0.30—air required H w/cm < 0.25—no air needed Admixtures —

16 High-Value Concrete High-Strength Concrete n Delays in delivery and placing must be eliminated n Consolidation very important to achieve strength n Slump generally 180 to 220 mm (7 to 9 in.) n Little if any bleeding—fog or evaporation retarders have to be applied immediately after strike off to minimize plastic shrinkage and crusting n 7 days moist curing Placing, Consolidation, and Curing

17 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

18 High-Value Concrete High-Durability Concrete n Abrasion Resistance n Blast Resistance n Permeability n Carbonation n Freeze-Thaw Resistance n Chemical Attack n Alkali-Silica Reactivity n Corrosion rates of rebar Durability Issues That HPC Can Address

19 High-Value Concrete n Cement: 398 kg/m 3 (671 lb/yd 3 ) n Fly ash: 45 kg/m 3 (76 lb/yd 3 ) n Silica fume: 32 kg/m 3 (72 lb/yd 3 ) n w/c: 0.30 n Water Red.: 1.7 L/m 3 (47 oz/yd 3 ) n HRWR: 15.7 L/m 3 (83 oz/yd 3 ) n Air: 5-8% n 91d strength: 60 MPa (8700 psi) High-Durability Concrete Confederation Bridge, Northumberland Strait, Prince Edward Island/New Brunswick, 1997

20 High-Value Concrete Self-Consolidating Concrete n developed in 1980s — Japan n Increased amount of u Fine material (i.e. fly ash or limestone filler) u HRWR/Superplasticizers n Strength and durability same as conventional concrete Self-consolidating concrete (SCC) also known as self-compacting concrete — flows and consolidates on its own

21 High-Value Concrete Self-Consolidating Concrete

22 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 SCC for Power Plant in Pennsylvania—Mix Proportions

23 High-Value Concrete Reactive-Powder Concrete (RPC) n Properties: u High strength — 200 MPa (can be produced to 810 MPa) u Very low porosity n Properties are achieved by: u Max. particle size  300  m u Optimized particle packing u Low water content u Steel fibers u Heat-treatment

24 High-Value Concrete Mechanical Properties of RPC Property Unit80 MPaRPC 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 <130 Freeze-thaw RDF90100 Carbonation mm20 Abrasion m 2 /s2751.2

25 High-Value Concrete Reactive Powder Concrete

26 High-Value Concrete n Cement n Sand n Silica quartz n Silica fume n Micro-Fibres - metallic or poly-vinyl acetate n Mineral fillers - Nano-fibres n Superplasticizer n Water Raw Material Components  uctal

27 High-Value Concrete What is the typical Ductal ® mix ? 230 kg/m kg/m kg/m kg/m 3 13 kg/m kg/m kg/m 3 Cement Silica fume Crushed Quartz Sand Fibres Superplasticizer Total water No aggregates !  uctal

28 High-Value Concrete What is the typical Ductal ® mix ? 9 – 10% % 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


Download ppt "Specialty Concrete - High End Value Materials. High-Value Concrete n All concrete is high value! u Cost of material (small) u Cost of placement (significant)"

Similar presentations


Ads by Google