Introduction to SCC and Federal Efforts

Transcription

1 Introduction to SCC and Federal Efforts Gary Jakovich, P.E. FHWA Federal Lands Bridge Office Sterling, VA Louis N. Triandafilou, P.E. FHWA Resource Center Baltimore, MD

2 Topics Covered Funding Program Introduction to SCC What is it? History of Development of SCC Performance Benefits of SCC Characteristics of SCC Mixture Applications of SCC Mix Design Principles Limitations and Areas of Concern Guidelines Research Efforts

3 IBRD Program Promote, Demonstrate, Evaluate and Document: Innovative designs, materials, construction methods, repair, rehabilitation techniques IBRC = $21 M/year IBRD= $13.1M/Year HPC = $4.125M/Year

4 What is SCC? Self Consolidating Concrete (SCC) is concrete that does not require vibration to achieve full consolidation.

5 Traditional Concrete Construction Vibration necessary Labor intensive Skill dependent Quality varies

6 Poor Consolidation

7 Drilled shafts with congested reinforcement High slump concrete would not do it. SCC will work!

8 History of SCC Developed in Japan in the late 1980 s Motivations: Decreasing Availability of Skilled Labor Quality without Vibration Durable Structures European consortium formed in 1996 Use in Europe has grown rapidly since

9 The Three Key Characteristics of SCC Ability to flow into forms Ability to pass through reinforcement Resistance to segregation

10 Benefits of Self-Consolidating No Vibration Needed (Reduced Labor Cost) Less Noise Better Pumpability Concrete Reduced Wear on Equipment Faster Construction Improved Durability through Better Consolidation High Strength

11 Filling ability SCC Demonstration Passing ability Resistance to segregation

12 SCC Deck Pour

13 SCC Prestressed Girders Used in Japan

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16 Applications of SCC in Japan Anchorages completed in 2 years rather than 2 ½ years!

17 Applications of SCC in Europe Cast time reduced by 35 40% Labor reduced by 50% No repair for defects

18 Precast SCC Railing In Spokane, WA

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26 I-4 Pedestrian Overpass Heathrow, Florida

27 Self-Consolidating Concrete (SCC) 2001: Precast arch bridge 5,000 psi, 2,500 coulomb 2005: 8 Bulb-T beams 8,000 psi, 1,500 coulomb

28 SCC Beams Rte 33 (2005)

29 Smooth Surface Finish

30 Bugholes Rte 33 SCC Regular

31 What makes the Difference Same Basic Ingredients as traditional concrete Mix Design Admixtures Superplasticizer Viscosity Modifier

32 General Principles of Mix Design Limit the maximum size of aggregate Use a high ratio of fine aggregate to coarse Use a well-distributed aggregate gradation Use superplasticizer (polycarboxylate works best) Use viscosity modifying admixture (VMA) Use low water/cement ratio

33 Current Limitations Test Standards Limited experience Cost implications Structural design specifications Construction specifications

34 Performance Concerns Cracks Due to Shrinkage Resulting from the large amount of fine aggregate Pressure on Formwork Modulus of Elasticity Strand Bond Loss of Flowability due to: Hot Weather Long Haul Distance Delays at the Job Site

35 Guidelines and Specifications PCI Interim Guidelines for Self-Consolidating Concrete published in 2003 PCI SCC Guide Specification currently under development ACI Committee 237 SCC Standard of Practice ACI Committee 211 Proportioning SCC ASTM Test Methods Slump Flow, J-Ring and Column Segregation

36 SCC at Auburn University SCC in Drilled Shafts

37 Problems with Drilled-Shaft Concrete Conventional Concrete Self-Consolidating Concrete Debris Tremie Debris Tremie

38 Use of SCC for Drilled-Shafts SCC technology has great potential for drilledshafts as it may: offer high flowability through reinforcement cage reduce the amount of bleed water offer more resistance to segregation offer sufficient workability after extended times (6-10 hours) SCC may thus minimize some of the problems encountered in the past.

39 Proportions for Drilled-Shaft Applications Mixture Constituents SCC Conv. DSC Type I/II Cement 465 pcy 500 pcy Class F Fly ash 230 pcy (33%) 125 pcy (20%) Fine Aggregate, ASTM C 33 (SSD) 1,280 pcy 1,216 pcy Coarse Aggregate Amount (SSD) 1,616 pcy 1,811 pcy Coarse Aggregate Description No. 78 River Gravel No. 67 Water 284 pcy 270 pcy Extended-Set Control Admixture 6 to 10 fl oz/cwt 6 to 10 fl oz/cwt Mid-Range Water Reducer 4 fl oz/cwt - Polycarboxylate High-Range Water Red. 4 to 6 fl oz/cwt 4 to 6 fl oz/cwt Viscosity-Modifying Admixture (VMA) 2 fl oz/cwt - w/cm Sand/Aggregate (by volume)

40 Slump Flow Loss Over Time Slump Flow (in.) Time (min.)

41 Conventional Concrete 7 Slump SCC 24 Slump flow 6. Exhumed sections

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46 Performance Specifications Workability Slump flow > 600 mm Remain flowable 90 minutes Withstand a slope of 3% Pumpable 90 minutes through pipes 100 m long

47 SCC Specifications Ohio DOT c. Provide fresh concrete for both the old mix and the new SCC mix for ODOT to produce shrinkage beams. Shrinkage tests will be performed on both mixes and compared. The SCC mix will not be allowed to exhibit more shrinkage than the old mix.

48 SCC Specifications Florida DOT Special Provisions issued December 2003 for Precast / Prestressed Concrete Products

49 FL DOT Special Provisions The slump flow spread shall be +2.5 in. of target. The Engineer may allow a maximum target slump flow spread of.. The difference between the slump flow spread with and without the J-ring shall be less than 2.0 in. [50 mm]. The slump flow time T 50 shall be between 2-7 sec. The VSI shall not exceed 2.

50 IL DOT SCC Specifications IL DOT QC/QA Program Addendum for Precast Concrete Products using SCC issued August 1, 2004 Defines Design Slump Flow Range, Product Slump Flow Range & Hardened VSI.

51 SCC Specifications Specifications should... Be realistic & practical Not overly restrictive Note that SCC is different from conventional HPC only in terms of its fluidity and ability to consolidate without the use of mechanical vibration.

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53 Passing Ability: J - Ring Test (ASTM C 1621)

54 Slump Flow Test J-Ring Column Segregation

55 Performance Specifications Mechanical Properties 28 day comp. Strength = Similar to HPC Creep and Shrinkage = Similar to HPC Durability Freeze-thaw resistance HPC

56 DOT Acceptance of SCC Alabama California Colorado Delaware Florida Hawaii Illinois Iowa Kansas Maine Maryland Michigan Minnesota Nebraska Nevada New Hampshire New Jersey New York Ohio Oregon Pennsylvania South Carolina Tennessee Texas Washington Utah Virginia

57 WA MA RI DE DC CA OR ID MT WY NV UT AZ NM TX OK CO SD ND MN WI IA AR LA MS GA SC FL TN VA MI IL VT NH CT NJ KS KY ME PA HI NE PR AK NY State DOT Acceptance of SCC

58 Innovative Bridge Research and Construction (IBRC) Colorado - columns, abutments, retaining walls Hawaii prestressed deck slabs Kansas inverted prestressed T-beams Michigan prestressed I-beams Nebraska p/s deck/superstructure system with 0.7 diameter strands New Hampshire prestressed deck slabs South Carolina prestressed I-beams Virginia prestressed Bulb-Tees

59 NCHRP Study NCHRP Project SCC for PC, PS Concrete Bridge Elements: Deliverables: Develop properties and performance criteria Provide mix design recommendations Recommend Test Methods Fresh and Hardened Properties Durability characteristics Structural Design and Construction Specifications

60 Closing Remarks Design SCC to meet project needs: Teamwork and Coordination is Required between: Designer Specification Writer Materials Engineer Contractor Subcontractor/Supplier SCC has major technical and economic advantages

61 Can we afford not to consider SCC?

62 Good HPC But poor consolidation!

63 Good HPC, But poor consolidation! SCC would have cost too much?

64 Think SCC in your next project! Intricate and complex forms Congested reinforcement Architectural surfaces Precast/Prefabricated elements Quality and high productivity

65 Thank You Danke Merci Grazie Efharisto ありがとう

66 Thank you. Any questions? Gary Jakovich, P.E. (703) FHWA Federal Lands Bridge Office or Lou Triandafilou, P.E. (410) FHWA Resource Center Baltimore