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the p2p initiative focus on innovation and quality

The P2P Initiative – Focus on Innovationand Quality

© National Ready Mixed Concrete Association

All rights reserved

announcement
Announcement
  • This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.
introduction
Introduction
  • Continuing education for engineers and architects
  • Length of Presentation: 1 Hours
  • Architects Earn 1 LUs
  • Engineers Earn 1 PDHs
  • NRMCA is an AIA/CES Registered Provider
  • Records kept on file with NRMCA and AIA/CES Records
what is the p2p initiative
What is the P2P Initiative?
  • Prescription-to-Performance
  • An alternative to current prescriptive specifications
  • An initiative of the concrete industry
  • Spearheaded by the NRMCA
p2p goals
P2P GOALS
  • Allow performance specifications as an alternative to current prescriptive specifications
  • Leverage expertise of all parties to improve quality and reliability of concrete construction
  • Assist architects/engineers to address concrete specifications in terms of functional requirements
  • Allow flexibility on the details of concrete mixtures and construction means and methods
  • Better establish roles and responsibilities based on expertise
  • Elevate the performance level and quality of ready mixed concrete
  • Foster innovation and advance new technology at a faster pace
what is a prescriptive specification
What is a prescriptive Specification?
  • Do not always cover intended performance
  • May conflict with intended performance
  • Limits competitive bidding
  • No incentive for quality control
  • Not in the owner’s best interest
prescriptive specification
Prescriptive Specification

Intended Performance

  • Placing/Finishing
  • Strength
  • Max Shrinkage
  • Resistance To:
    • Freeze-Thaw
    • Deicer scaling
    • Corrosion
    • Sulfate attack
    • ASR
    • Cracking
    • Abrasion

Typical Criteria

  • Slump
  • Max w/cm ratio
  • Min cement content
  • Min/max air
  • Min/Max pozzolans/slag
  • Blended cements
  • Aggregate grading
  • Source Limitations
  • Chloride Limits
water cement ratio
Water-cement Ratio

Air

Air

Water

Water

Paste

Cement

Cement

what is a performance specification
What is a Performance Specification?
  • Focus on performance and function
  • Flexibility to adjust mixture ingredients and proportions to achieve consistent performance
  • Measurable and enforceable
benefits to the owner
Benefits to the Owner
  • Improved quality
  • Improved performance
  • Reduced construction time
  • Reduced cost
  • Higher confidence in concrete construction
benefits to the engineer architect
Benefits to the Engineer/Architect
  • Focus on function rather than composition
    • Strength, Durability, Shrinkage, etc.
  • Simplified submittal review
  • Improved product consistency
  • Reduced conflict with contractor/producer
  • Reduced risk – contractor and producer are responsible for performance
benefits to the contractor
Benefits to the Contractor
  • Improved communication/coordination
  • Constructability requirements addressed
  • Predictable performance
  • Innovate on construction means and methods
benefits to the producer
Benefits to the Producer
  • Eliminates conflicts and improves clarity in specifications
  • Encourages innovation and rewards investment in quality control
  • Allows optimization of mixtures for performance
  • Allows adjustment of materials/proportions to compensate for material or ambient conditions variations
what are the challenges
What are the Challenges?
  • Acceptance of Change
  • Trust / Credibility
  • Knowledge Level (training)
  • Reference Codes and Specifications
    • Prescriptive limitations
  • Measurement and Testing
    • Reliability of existing tests
    • Reliability of jobsite tests
what activities are underway
What Activities are Underway?
  • Communication
    • Engineers, Architects, Contractors, and Producers
    • Articles and presentations
  • Developing Producer Quality System / Qualifications
  • Developing Model Spec / Code Revisions
    • Look at model codes from other countries (Canada, Europe, Australia)
    • Look at similar initiatives in the US (FHWA and DOTs)
  • Documenting Case Studies
  • Conducting Research
    • Test Methods for Performance
    • Quantifying differences between prescriptive and performance mixes
  • Delivering Training Programs
lab study demonstrating advantages of performance specification
Lab Study Demonstrating Advantages of Performance Specification
  • Case 1: Real Floor Specification from a Major Owner
  • Case 2: Typical HPC Bridge Deck Specification
  • Case 3: ACI 318 Chapter 4 Code – prescriptive durability provisions
fresh concrete tests
Fresh Concrete Tests
  • Fresh Concrete Properties
    • Slump: ASTM 143
    • Air Content: ASTM C 231
    • Density: ASTM C 138
    • Temperature: ASTM C 1064
    • Initial Setting Time (Case 1): ASTM C 403
    • Finishability (Case 1): Subjective rating (5=Excellent to 1=Poor)
    • Segregation (Case 1): Cylinders vibrated, density of top and bottom half compared
hardened concrete tests
Hardened Concrete Tests
  • Compressive Strength, ASTM C 39
  • Length Change, ASTM C 157
durability tests
Durability Tests
  • Rapid Chloride Permeability Test (RCPT), ASTM C 1202
  • Rapid Migration Test (RMT), AASHTO TP 64
  • Sorptivity, ASTM C 1585
  • Bulk Diffusion, ASTM C 1556
experimental program 5 concrete mixtures
Experimental Program (5 concrete mixtures)
  • One control (prescriptive) and 4 performance mixtures

FS-1: CM = 611, w/cm = 0.49, 8-18% aggregate

FS-2: CM = 517, w/cm = 0.57, 8-18% aggregate

FS-3: CM = 530, 20% FA, w/cm = 0.57, 8-18% aggregate

FS-4: CM = 530, 20% FA with binary aggregates, w/cm = 0.53, #467 stone aggregate

FS-5: CM = 530, 20% SL, 15% FA with binary aggregates, w/cm = 0.54, #467 stone aggregate

segregation shrinkage
Segregation & Shrinkage
  • Segregation Index: Difference in the coarse aggregate content was consistently about 20% except for Mixture FS-5 which was about 15%
  • Shrinkage: All mixtures except FS-5 had 28 day shrinkage < 0.020%
summary floor slab mixtures
Summary – Floor Slab Mixtures
  • All performance mixtures met performance requirements except Mixture FS-5
  • Strength over-design factor, limiting w/cm increased cement contents
  • Use of SCMs was beneficial
  • Continuous aggregate grading mixtures did not impact performance
  • Performance mixtures had substantial material costs savings
experimental program 4 mixtures
Experimental Program (4 mixtures)
  • One control (prescriptive) and 3 performance mixtures

BR-1: C = 550, Class F FA = 105, SF = 50; Total = 705

BR-2: C = 426, Class F FA = 150, SF = 24; Total = 600

BR-3: C = 300, SL = 300; Total = 600

BR-4: C = 426, Class F FA = 150, UFFA = 34; Total = 612

  • w/cm=0.39 for all mixtures except 0.36 for Mix 4
strength
Strength
  • Compressive Strength: 28 day strengths were much higher than specified (6800 to 8970 psi)
rapid migration test
Rapid Migration Test
  • FHWA Performance Grade (AASHTO TP 64)
    • Grade 1: RCPT = 2000 to 3000; RMT = 0.024 to 0.034
    • Grade 2: RCPT = 800 to 2000; RMT = 0.012 to 0.024
    • Grade 3: RCPT < 800; RMT < 0.012
summary hpc bridge deck mixtures
Summary – HPC Bridge Deck Mixtures
  • All performance mixtures met performance requirements
  • Performance mixtures had similar or better performance than Prescriptive mixtures
    • Drying shrinkage, workability (stickiness), HRWR dosage, strength, RCPT, RMT
  • Performance mixtures had substantial material cost savings
case 3 aci 318 chapter 4 prescriptive durability provisions
Case 3 - ACI 318 Chapter 4 Prescriptive durability provisions
  • Objective: Determine if w/cm is the best measure for durability (permeability).
experimental program 4 mixtures38
Experimental Program (4 mixtures)
  • One control (prescriptive) and 3 performance mixtures

318-1: 750 lbs Portland cement mixture

318-2: CM = 700; 25% FA (1.16% less paste)

318-3: CM = 564; 25% FA (7.24% less paste)

318-4: Same as #3 but yield adjusted largely by coarse aggregate

  • w/cm = 0.42
  • Slump = 3.75” – 6.5”; Air = 4.1% to 7.4%
summary aci 318 mixtures
Summary – ACI 318 Mixtures
  • Code limitations on w/cm are no guarantee for high durability concrete
  • Considerable advances in the use of SCMs and chemical admixtures
  • Code durability provisions should be performance based
conclusions
Conclusions
  • Prescriptive specs do not assure performance
  • Performance mixtures achieved equal or better performance
  • Great opportunity for mixture optimization
  • Producers compete on their knowledge, resources
  • ACI 318 durability provisions needs to change
aci 318 chapter 4 restructuring
ACI 318 Chapter 4 Restructuring
  • Exposure Category F – Exposure to freezing and thawing cycles
  • Exposure Category S – Exposure to water-soluble sulfates
  • Exposure Category P – Conditions that require low permeability concrete
  • Exposure Category C – Conditions that require additional corrosion protection of reinforcement
future specification for concrete
Future Specification for Concrete
  • Concrete for parking garage slabs and beams shall meet the following requirements:
  • Specified compressive strength, f’c = 5,000 psi
  • Exposure class F3, S0, P1, C2
resources
Resources
  • Visit www.nrmca.org/P2P
  • Download Example Specifications
  • Download P2P Articles
  • Download Research Studies