The P2P Initiative – Focus on Innovation and Quality © National Ready Mixed Concrete Association All rights reserved

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 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? Prescription-to-Performance An alternative to current prescriptive specifications An initiative of the concrete industry Spearheaded by the NRMCA

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

Water-cement Ratio Cement Water Air Cement Water Air Paste

Does w/c alone control strength?

Does w/c alone control permeability?

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 Improved quality Improved performance Reduced construction time Reduced cost Higher confidence in concrete construction

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 Improved communication/coordination Constructability requirements addressed Predictable performance Innovate on construction means and methods

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? 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? 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 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 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 Compressive Strength, ASTM C 39 Length Change, ASTM C 157

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

Case 1 - Concrete Floor Specification PrescriptivePerformance Specified = 4000 psi; Average = 5200 psi Specified = 4000 psi; Average past records Max w/c = 0.52, penalties, rejected- No fly ash or slagSCMs may be used Slump (max) = 4”, Non AESlump = 4” – 6”, Non AE Combined aggregate gradation 8% - 18% - No HRWR- -Shrinkage < 0.04% at 28 days -Setting Time = 5 ± ½ hours Specified by Contractor

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

Combined Aggregate Grading of FS Mixtures

Compressive Strength and Setting Time

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%

Slab Finishability Test All 5 concrete mixtures had a rating above 4.5 indicating excellent finishability

Durability

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

Case 2 - HPC Bridge Deck Specification PrescriptivePerformance Specified 28 d strength=4000 psi; Average past records Max w/cm = Total CM = % FA plus 7% to 8% SF SCM required. Maximum amounts per ACI 318 for deicer scaling Air = 4% to 8% RCPT < 1500 coulombs -Shrinkage < 0.04% at 28 days Slump = 4” – 6” Specified by Contractor

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 Compressive Strength: 28 day strengths were much higher than specified (6800 to 8970 psi)

RCPT (ASTM C 1202), RMT (AASHTO TP 64)

Rapid Migration Test FHWA Performance Grade (AASHTO TP 64) Grade 1: RCPT = 2000 to 3000; RMT = to Grade 2: RCPT = 800 to 2000; RMT = to Grade 3: RCPT < 800; RMT < 0.012

Drying Shrinkage (ASTM C 157)

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 Objective: Determine if w/cm is the best measure for durability (permeability).

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%

Results At same w/cm=0.42 Mix Compressive Strength – 28 days, psi 5,4405,9505,6705,600 Length Change – 180 days, % 0.064%0.048%0.037%0.032% RCPT – 180 days, coulombs RMT – 180 days, mm/V-hr

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 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 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

Exposure to freezing and thawing cycles Exposure Category F – Exposure to freezing and thawing cycles ClassDescriptionCondition F0Concrete not exposed to freezing and thawing cycles F1ModerateOccasional exposure to moisture F2SevereContinuous contact with moisture F3Very Severe Continuous contact with moisture and exposed to deicing chemicals

Exposed to water-soluble sulfates Exposure Category S – Exposure to water-soluble sulfates ClassDescription Water-soluble sulfate (SO 4 ) in Soil, percent by weight Sulfate (SO 4 ) in Water, ppm S0NegligibleSO 4 <0.10SO 4 <150 ppm S1Moderate0.10≤ SO 4 < ≤ SO 4 <1500 ppm Seawater S2Severe0.20≤ SO 4 < ≤ SO 4 <10,000 ppm S3 Very Severe SO 4 >2.00SO 4 >10,000 ppm

Conditions that require low permeability concrete Exposure Category P – Conditions that require low permeability concrete ClassCondition P0Low permeability to water not applicable P1Concrete intended to have low permeability to water

Conditions that require additional corrosion protection of reinforcement Exposure Category C Conditions that require additional corrosion protection of reinforcement ClassCondition C0 Additional corrosion protection not a concern – for concrete that will be dry or protected from moisture in service C1 Exposure to moisture but will not be exposed to external source of chlorides in service C2 Exposure to moisture and an external source of chlorides in service – from deicing chemicals, salt, brackish water, seawater, or spray from these sources

Requirements for Concrete - Exposure Class F Exposure Class Max w/cm Min f’ c psi Additional Minimum Requirements F0--- F Table F Table F Table 4.4.1Table 4.4.2

Table 4.4.1—Total Air Content for Concrete Exposed to Cycles of Freezing and Thawing Nominal maximum aggregate size, in. * Air content, percent Class F2 and F3Class F1 3/ / / / †2† 54 3†3† 3.5

Table 4.4.2—Requirements for Concrete Subject to Deicing Exposure Class F3 Cementitious materials Maximum percent of total cementitious materials by weight* Fly ash or other pozzolans conforming to ASTM C Slag conforming to ASTM C Silica fume conforming to ASTM C Total of fly ash or other pozzolans, slag, and silica fume 50 † Total of fly ash or other pozzolans and silica fume 35 †

Requirements for Concrete - Exposure Class S Exposure Class Max w/cm Min f’ c psi Additional Minimum Requirements S0--- S Cement Types II, IP(MS), IS(MS), P(MS), I(PM)(MS), I(SM)(MS) S Cement Type V No calcium chloride admixtures S Cement Type V + pozzolan ‡ No calcium chloride admixtures

Requirements for Concrete - Exposure Class P Exposure Class Max w/cm Min f’ c psi Additional Minimum Requirements P0--- P

Requirements for Concrete - Exposure Class C Exposure Class Max w/cm Min f’ c psi  Max water-soluble chloride ion (Cl − ) content in concrete, percent by weight of cement Additional Requirement Reinforced Concrete C C C  Min. Cover Prestressed Concrete C C C  Min. Cover

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 Visit Download Example Specifications Download P2P Articles Download Research Studies

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