1、The P2P Initiative: Performance-based Specs for Concrete,NRMCA Continuing Education Series, 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 d
2、eemed 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 Hour Architects Ear
3、n 1 LU Engineers Earn 1 PDH NRMCA is an AIA/CES Registered Provider Records kept on file with NRMCA and AIA/CES Records,Outline,What is the P2P Initiative? What is a Prescriptive Specification? What is a Performance Specification? What are the Benefits of P2P? What Activities are Underway? How to Sp
4、ecify Concrete using Current Codes?,What is the P2P Initiative?,Stands for Prescription-to-Performance Initiative of the ready mixed industry through the NRMCA Coordinated by P2P Steering Committee under the NRMCA Research, Engineering and Standards Committee Members include technical representative
5、s, product suppliers, contractors, engineers, and architects,Why Performance?,Shifting Expertise to Concrete Producers Reduce Conflicts in Specifications Identify Roles and Responsibilities Controlling Construction Cost (through optimization) Meet Greater Demands on the Product (through innovation)
6、Improving Quality Systems Training and Certification Programs,Construction Cost Savings of P2P,Innovative construction means and methods Improved construction schedules More efficient structural designs Simplified specifications and submittal process Optimized mix designs,Innovative Technologies,Hig
7、h-Strength Concrete,High-Performance Concrete,Self- Consolidating Concrete,Improved Quality Systems,Product Development,Testing Labs,Material Handling,NRMCA Training and Certifications,Plant and Truck Certification Plant Manager Certification Concrete Technologist Certifications Certified Delivery P
8、rofessional (drivers) Concrete Certified Sales Professional Under development Concrete technologist responsible for performance mixes Concrete producer certification based on quality system,P2P Goals,Allow performance specifications as an alternative to current prescriptive specifications Leverage e
9、xpertise 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 r
10、esponsibilities based on expertise Continue to elevate the performance level of the ready mixed concrete industry Foster innovation and advance new technology at a faster pace,What is a Prescriptive Specification?,Details mixture proportions and construction means and methods Do not always cover int
11、ended performance May conflict with intended performance Example: Low w/c for durability could increase thermal and shrinkage cracking Requirements are generally not directly enforceable Producer held responsible for performance and defects, even though he lacks the freedom to make changes Prevents
12、mixture optimization for performance No incentive for quality control / batch uniformity,Prescriptive Specification,Intended Performance Placing/Finishing Strength Min Shrinkage Resistance To: Freeze-Thaw Corrosion Sulfate attack ASR Cracking Abrasion,Prescriptive Criteria Slump Max w/cm ratio Min c
13、ement content Min/max air Min/Max pozzolans/slag Blended cements Aggregate grading Source Limitations Chloride Limits,Prescriptive Specification,Intended Performance Placing/Finishing Strength Min Shrinkage Resistance To: Freeze-Thaw Corrosion Sulfate attack ASR Cracking Abrasion,Prescriptive Criter
14、ia Slump Max w/cm ratio Min cement content Min/max air Min/Max pozzolans/slag Blended cements Aggregate grading Source Limitations Chloride Limits,Some prescriptive criteria are required by code but many are not,Prescriptive Specification Example,w/c ratio = 0.40 Min. cement = 600 pcy Strength = 350
15、0 psi No SCM Aggregate grading 8 18% No reactive aggregate Low alkali cement Shrinkage = 0.04% max,No cracking No curling Slump 5 1 inch Setting time 4 0.5 hrs Max temp 85 F Impermeable Uniform color,Example: Water Cement Ratio,Paste,w/cm alone does not control strength,Source: ACI 211,w/cm alone do
16、es not control permeability,Source: ACI 232, 233, 234,What is a Performance Specification?,Performance requirements of concrete Hardened state for Service (meeting owners requirements) Plastic state for Constructability (meeting the contractors requirements) Focus on performance and function Assignm
17、ent of responsibility Flexibility to adjust mixture ingredients and proportions to achieve consistent performance Changes in weather conditions Changes in materials Measurable and enforceable Defined test methods and acceptance criteria,How would it work?,Qualification requirements would be establis
18、hed for producers Performance criteria would be specified by the A/E Contractor would partner with producer to establish constructability criteria Submittal will demonstrate compliance with specified requirements Compliance through pre-qualification tests and limited jobsite acceptance tests,Who Ben
19、efits from P2P?,Owners Engineers/Architects Concrete Contractors Concrete Producers,Benefits to Owners from P2P,Improved quality Improved performance Reduced construction time Reduced cost Higher confidence in concrete construction Innovative solutions,Benefits to Engineers/Architects,Focus on funct
20、ion rather than composition Strength, Durability, Shrinkage, etc. Simplified submittal review Improved product consistency Reduced conflict with contractor/producer Reduced risk Producer responsible for concrete mix design Innovative solutions,Benefits to the Contractors,Improved communication / coo
21、rdination Constructability requirements addressed Predictable performance Innovate on construction means and methods,Benefits to Concrete Producers,Eliminates conflicts in specifications Improved clarity in what needs to be furnished Encourages innovation Rewards investment in quality control Allows
22、 optimization of mixtures for performance Allows adjustment of materials/proportions to compensate for changes in materials and weather Provide innovative products,What are the Challenges?,Acceptance of Change Trust / Credibility Knowledge Level (training) Reference Codes and Specifications Prescrip
23、tive 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 / Cod
24、e 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 Prog
25、rams,How to Specify Concrete Using Current Codes,Objective: Minimize prescriptive requirements Comply with ACI 318 Chapter 3, 4 and 5 Example: 3 story concrete building with first level parking Structural slabs, beams, and columns Slabs-on-grade (parking) Foundation walls Footings Freezing and thawi
26、ng (with deicing chemicals) Soils contain sulfates (severe) Unusual to have freeze-thaw and sulfate exposure Items in are comments Most concrete does not require prescriptive criteria,Yellow,Classes of Concrete for the Project,Class 1 and 2 strength is governed by structural design requirements Clas
27、s 3 and 4 strength is governed by durability requirements,Part 1 - General,1.1 RELATED DOCUMENTS 1.2 SUMMARY 1.3 DEFINITIONS 1.4 SUBMITTALS 1.5 QUALITY ASSURANCE 1.6 DELIVERY, STORAGE, AND HANDLING,Submittals,Submit field or laboratory test records for each class of concrete to demonstrate concrete
28、will meet: Required average compressive strength Other specified requirements in section 2.12 Test data should meet the following requirements Test data from concrete supplied from the same production facilities proposed for the work Test data from concrete mixtures containing similar materials prop
29、osed for the work,Submittals (contd),Submit properties of mix design for each class of concrete including: Specified compressive strength, c Documentation of strength test results indicating the standard deviation Required average compressive strength, cr Average compressive strength of proposed mix
30、ture Placement method Slump or slump flow Air content Density w/cm ratio Maximum aggregate size Sources and designations of ingredient materials,Some properties will be specified and others will be selected by producer and contractor Slump is one example. Slump should not be specified but selected b
31、y the contractor and producer since this is means and methods,Submittals (contd),Submit documentation indicating installer, manufacturer, and testing agency meet the qualifications specified in Section 1.5 Quality Assurance.,Quality Assurance,Installer Qualifications: On-site supervisor of the finis
32、hing crew who qualified as ACI Certified Concrete Flatwork Technician for flatwork placing and finishing.,Flatwork finisher certification is important for constructing slabs General standard of care of concrete construction is addressed in this certification program,Quality Assurance (contd),Manufac
33、turer Qualifications: NRMCA Certified Ready Mixed Concrete Production Facility NRMCA Concrete Technologist Level 2,NRMCA certified concrete production facilities demonstrate compliance with requirements of ASTM C 94 Includes an annual certification of delivery vehicles The NRMCA Concrete Technologis
34、t Level 2 Certification validates personnels knowledge of fundamentals of concrete technology including mixture proportioning. Certification is obtained by passing a 90 minute exam administered by NRMCA with ACI Grade 1 Field Testing Technician Certification as the prerequisite. Details available at
35、 www.nrmca.org/certifications .,Quality Assurance (contd),Testing Agency Qualifications: Meet the requirements of ASTM C 1077. Field testing: ACI Concrete Field Testing Technician Grade I. Lab testing: ACI Concrete Strength Testing Technician or ACI Concrete Laboratory Testing Technician Grade I. Te
36、st results for the purpose of acceptance shall be certified by a registered design professional employed with the Testing Agency.,Concrete testing is very sensitive to the way specimens are collected, cured, and tested. Proper field and lab procedures are essential to achieving meaningful results.,Q
37、uality Assurance (contd),Pre Installation Conference: Require representatives of each entity directly concerned with cast-in-place concrete to attend, including: Architect Structural Engineer Contractor Installer (Concrete Contractor) Pumping Contractor Manufacturer (Ready-mixed concrete producer) I
38、ndependent testing agency,NRMCA and American Society of Concrete Contractors has a document titled Checklist for the Concrete Pre-Construction Conference that can be used as a guide,Part 2 - Products,2.1 MANUFACTURERS 2.2 FORMING MATERIALS 2.3 STEEL REINFORCEMENT 2.4 REINFORCEMENT ACCESSORIES 2.5 CO
39、NCRETE MATERIALS 2.6 WATERSTOPS 2.7 VAPOR RETARDERS 2.8 FLOOR AND SLAB TREATEMENTS 2.9 CURING MATERIALS 2.10 RELATED MATERIALS 2.11 REPAIR MATERIALS 2.12 CONCRETE MIXTURES,Concrete Materials,Cementitious Materials: Use materials meeting the following requirements with limitations specified in Sectio
40、n 2.12. Hydraulic Cement: ASTM C 150 or ASTM C 1157 or ASTM C 595 Fly Ash: ASTM C 618 Slag: ASTM C 989 Silica Fume: ASTM C 1240,Avoid listing brand names for most materials in this section if a standard for the product already exists. Many existing standards are performance-based. Avoid limiting the
41、 type or quantities of cementitious materials that can be used unless required for certain performance attributes as listed in Section 2.12 Concrete Mixtures.,Concrete Materials (contd),Normalweight Aggregate: ASTM C 33 Water: ASTM C 1602 Fibers: ASTM C 1116,Concrete Materials (contd),Chemical Admix
42、tures: Air Entraining: ASTM C 260 Water reducing, accelerating and retarding: ASTM C 494 Admixtures for flowing concrete: ASTM C 1017 Admixtures with no standard designation shall be used only with the permission of the design professional when its use for specific properties is required.,Avoid limi
43、ting the type of admixtures that can be used unless there is a specific reason (eg. Chloride based admixtures for corrosion). Consider specifying or allowing the use of admixtures which do not have a specific ASTM designation with appropriate documentation indicating beneficial use to concrete prope
44、rties. These include colors, viscosity modifying admixtures, hydration stabilizing admixtures, pumping aids, anti-freeze admixtures, etc.,Concrete Mixtures,Prepare design mixtures for each class of concrete on the basis of field test data or laboratory trial mixtures, or both according to ACI 318, C
45、hapter 5. Design mixtures shall meet the requirements listed in Table 2.12.,Concrete Mixtures (contd),Provide a schedule of concrete classes of the structure including a description of exposure. Provide limits on materials based on Chapter 3 and 4 of ACI 318,Concrete Mixtures (contd),Few limits on m
46、aterials for class 1 and 2 since durability is not a concern No maximum water-cement ratio or minimum cement content Compressive strength based on structural design requirements Maximum aggregate size controlled by ACI 318 3.3 Aggregates 1/5 narrowest dimension of forms 1/3 slab depth 3/4 minimum cl
47、ear spacing between reinforcement (governs) Maximum chloride ions controlled by ACI 318 4.4 for corrosion protection of reinforcement that will be dry or protected from moisture in service,Concrete Mixtures (contd),Class 3 concrete is exposed to freeze-thaw, deicing chemicals, and severe sulfates Co
48、mpressive strength, air content, maximum w/cm based on ACI 318 4.2 Freezing and thawing exposure. Limits on SCMs based on ACI 318 4.2.3 for concrete exposed to deicing chemicals: Fly ash, 25% max Slag, 50% max Silica fume, 10% max Total of fly ash, slag, and silica fume, 50% max Total of fly ash and
49、 silica fume, 35% max Limits on cement type, calcium chloride admixtures, strength, and w/cm are based on ACI 318 4.3 Sulfate exposure. Type V cement must be used,Concrete Mixtures (contd),Class 4 concrete is exposed to severe sulfates Compressive strength, cement type, maximum w/cm, and restriction
50、 on using calcium chloride admixtures are based on ACI 318 4.3 Sulfate exposure Type V cement must be used,PART 3 - Execution,3.1 FORMWORK 3.2 EMBEDDED ITEMS 3.3 REMOVING AND REUSING FORMS 3.4 SHORES AND RESHORES 3.5 VAPOR RETARDERS 3.6 STEEL REINFORCEMENT 3.7 JOINTS 3.8 WATERSTOPS 3.9 CONCRETE PLACEMENT 3.10 FINISHING FORMED SURFACES 3.11 FINISHING FLOORS AND SLABS 3.12 MISCELLANEOUS CONCRETE ITEMS 3.13 CONCRETE PROTECTING AND CURING 3.14 LIQUID FLOOR TREATEMENTS 3.15 JOINT FILLING 3.16 CONCRETE SURFACE REPAIRS 3.17 FIELD QUALITY ASSURANCE,
