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Precast Concrete Guide Specification | Concrete | Reinforced Concrete
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PART 1: GENERAL 1.1 REFERENCES 1.2 GENERAL REQUIREMENTS 1.3 SUBMITTALS 1.3.1 Preconstruction Submittals 1.3.2 Shop Drawings 1.3.3 Precast Concrete Unit Data 1.3.4 Design Data 1.3.5 Test Reports 1.3.6 Certificates 1.4 DESIGN 1.4.1 Standard Precast Concrete Unit Design 1.4.2 Non-Standard Precast Concrete Unit Design 1.4.3 Franchise Precast Concrete Units 1.4.4 Joints and Sealants 1.4.5 Concrete Mix Design 1.4.5.1 Concrete Proportions 1.4.5.2 Durability and Performance Requirements 1.4.5.2.1 Concrete Compressive Strength 1.4.5.2.2 Water Cement Ratio 1.4.5.2.3 Air Content 1.5 QUALITY ASSURANCE 1.5.1 NPCA Plant Certification 1.5.2 Qualifications, Quality Control and Inspection 1.5.2.1 Qualifications 1.5.2.2 Quality Control 1.5.2.3 Inspection 1.6 HANDLING, STORAGE AND DELIVERY 1.6.1 Handling 1.6.2 Storage 1.6.3 Delivery 1.6.4 Final Acceptance PART 2: PRECAST CONCRETE UNITS 2.1 MANUFACTURERS 2.2 MATERIALS 2.2.1 Cement 2.2.2 Silica Fume 2.2.3 Fly Ash and Pozzolans 2.2.4 Ground Granulated Blast-Furnace Slag 2.2.5 Water 2.2.6 Aggregates 2.2.6.1 Aggregate Selection 2.2.6.2 Aggregates for Lightweight Concrete
2.2.7 Admixtures 2.2.7.1 Air-Entraining 2.2.7.2 Accelerating, Retarding, Water Reducing [Moderate to High] 2.2.7.3 Pigments 2.2.7.4 Corrosion Inhibitors 2.2.8 Reinforcement 2.2.8.1 Reinforcing Bars 2.2.8.1.1 Deformed Billet-steel 2.2.8.1.2 Deformed Low-alloy steel 2.2.8.2 Reinforcing Wire 2.2.8.2.1 Plain Wire 2.2.8.2.2 Deformed Wire 2.2.8.3 Welded Wire Reinforcement 2.2.8.3.1 Plain Wire 2.2.8.3.2 Deformed Wire 2.2.8.4 Epoxy-Coated Reinforcement 2.2.8.4.1 Reinforcing Bars 2.2.8.4.2 Wire and Welded Wire Reinforcement 2.2.8.5 Galvanized Reinforcement 2.2.9 Inserts and Embedded Metal 2.2.9.1 Structural Steel Plates, Angles, etc. 2.2.9.2 Hot-dipped Galvanized 2.2.9.3 Proprietary Items 2.2.10 Joint Sealants and Joint Gaskets 2.2.10.1 Rubber Gaskets for Circular Concrete Sewer Pipe and Culvert Pipe 2.2.10.2 External Sealing Bands for Noncircular Sewer, Storm Drain and Culvert Pipe 2.2.10.3 Preformed Flexible Joint Sealants for Concrete Pipe, Manholes, and Manufactured Box Sections 2.2.10.4 Elastomeric Joint Sealants 2.2.11 Pipe Entry Connectors 2.2.12 Grout 2.2.12.1 Nonshrink Grout 2.2.12.2 Cementitious Grout 2.3 MANUFACTURE 2.3.1 Forms 2.3.2 Reinforcement 2.3.3 Embedded Items 2.3.4 Concrete 2.3.4.1 Concrete Mixing 2.3.4.2 Concrete Placing 2.3.4.2.1 Cold Weather Concreting 2.3.4.2.2 Hot Weather Concreting 2.3.4.3 Concrete Curing 2.3.4.3.1 Curing by Moisture Retention 2.3.4.3.2 Curing with Heat and Moisture 2.3.4.4 Surface Finish 2.3.4.4.1 Formed Non-Architectural Surfaces 2.3.4.4.2 Unformed Surfaces 2.3.4.4.3 Special Finishes 2.3.4.4.4 Architectural Finishes 2.3.4.5 Stripping Precast Concrete Units From Forms 2.3.4.6 Patching and Repair 2.3.4.6.1 Repairing Minor Defects 2.3.4.6.2 Repairing Honeycombed Areas 2.3.4.6.3 Repairing Major Defects
2.3.4.7 Shipping Precast Concrete Units PART 3: EXECUTION 3.1 INSTALLATION 3.1.1 Site Access 3.1.2 Installation 3.1.3 Watertightness 3.2 FIELD QUALITY CONTROL 3.2.1 Job Site tests 3.2.1.2 Vacuum Testing 3.2.1.2 Hydrostatic Testing
*********************************************************************** NOTE: This guide specification covers the requirements for plant manufactured precast concrete products. Comments and suggestions regarding this specification are welcome and should be directed to the NPCA Technical Services Department. Please visit the NPCA Web site at www.precast.org. Brackets are used in the text to indicate designer choices or locations where text must be supplied by the designer. ***********************************************************************
PART 1: GENERAL 1.1 REFERENCES Where applicable, the latest editions of the following standards shall form a part of this specification to the extent referenced. The publications are referenced to in the text of this guide specification by the basic designation only.
American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Highway Bridges Guide Specifications for Structural Design of Sound Barriers Standard Specification for Transportation Materials and Methods of Sampling and Testing ACI INTERNATIONAL (ACI) ACI 211.1 Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete Standard Practice for Selecting Proportions for Structural Lightweight Concrete
ACI 211.3
Guide for Selecting Proportions for No-Slump Concrete Guide for Measuring, Mixing, Transporting, and Placing Concrete Hot Weather Concreting Cold Weather Concreting Consolidation of Concrete Building Code Requirements for Structural Concrete Code Requirements for Environmental Engineering Concrete Structures and Commentary Accelerated Curing of Concrete at Atmospheric Pressure
ACI 305R ACI 306R ACI 309R ACI 318
AMERICAN CONCRETE PIPE ASSOCIATION (ACPA) ACPA Concrete Pipe Handbook ACPA Design Manual
ASTM INTERNATIONAL (ASTM) ASTM A 36 Specification for Carbon Structural Steel Specification for Steel Wire, Plain, for Concrete Reinforcement Specification for Fabricated Deformed Steel Mats for Concrete Reinforcement Specification for Steel Welded Wire Reinforcement, Plain, for Concrete Specification for Steel Wire, Deformed, for Concrete Reinforcement Specification for Steel Welded Wire Reinforcement, Deformed, for Concrete Specification for Deformed and Plain Billet-Steel Bars for Concrete Reinforcement
ASTM A 82
ASTM A 184
ASTM A 496
Specification for Low-Alloy Steel Deformed and Plain Bars for Concrete Reinforcement Specification for Zinc-Coated (Galvanized) Steel Bars for Concrete Reinforcement Specification for Epoxy-Coated Reinforcing Steel Bars Specification for Epoxy-Coated Steel and Welded Wire Fabric for Reinforcement Standard Specification for Concrete Sewer, Storm Drain, and Culvert Pipe Standard Practice for Making and Curing Concrete Test Specimens in the Field Specification for Concrete Aggregates Test Method for Compressive Strength of Cylindrical Concrete Specimens Test Method for Organic Impurities in Fine Aggregates for Concrete Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete Standard Test Method for Surface Moisture in Fine Aggregate Specification for Reinforced Concrete Culvert, Storm Drain and Sewer Pipe Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading) Specification for Ready-Mixed Concrete Standard Test Method for Materials Finer than 75- m (No. 200) Sieve in Mineral Aggregates by Washing Standard Test Method for Lightweight Particles in Aggregate
ASTM A 767 ASTM A 775
ASTM A 884
ASTM C 31 ASTM C 33
ASTM C 40
ASTM C 70
ASTM C 78 ASTM C 94
Standard Terminology Relating to Concrete and Concrete Aggregates Test Method for Sieve Analysis of Fine and Coarse Aggregates Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete Standard Test Method for Clay Lumps and Friable Particles in Aggregates Test Method for Slump of Hydraulic Cement Concrete Specification for Portland Cement Standard Practice for Sampling Freshly Mixed Concrete Test Method for Air Content of Freshly Mixed Concrete by Volumetric Method Practice for Making and Curing Concrete Test Specimens in the Laboratory Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method Specification for Air-Entraining Admixtures for Concrete Specification for Lightweight Aggregates for Structural Concrete Specification for Reinforced Concrete Low-Head Pressure Pipe Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance Specification for Joints for Circular Concrete Sewer and Culvert Pipe, Using Rubber Gaskets Specification for Precast Reinforced Concrete Manhole Sections Standard Specification for Chemical Admixtures for Concrete
ASTM C 142 ASTM C 143 ASTM C 150
ASTM C 443
Test Methods for Concrete Pipe, Manhole Sections, or Tile Standard Specification for Reinforced Concrete Arch Culvert, Storm Drain, and Sewer Pipe Standard Specification for Reinforced Concrete Elliptical Culvert, Storm Drain, and Sewer Pipe Test Method for Total Evaporable Moisture Content of Aggregate by Drying Specification for Blended Hydraulic Cements Standard Practice for Capping Cylindrical Concrete Specimens Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Concrete Standard Specification for Reinforced Concrete DLoad Culvert, Storm Drain, and Sewer Pipe Test Method for Resistance of Concrete to Rapid Freezing and Thawing Specification for Concrete Made by Volumetric Batching and Continuous Mixing Test Method for Rebound Number of Hardened Concrete Standard Terminology Relating to Concrete Pipe and Related Products Specification for Precast Concrete Barriers Practice for Minimum Structural Design Loading for Underground Precast Concrete Utility Structures Specification for Underground Precast Concrete Utility Structures Specification for External Sealing Bands for Concrete Pipe, Manholes and Precast Box Sections
ASTM C 507
ASTM C 566 ASTM C 595
ASTM C 617
ASTM C 685
ASTM C 822 ASTM C 825
ASTM C 857
ASTM C 858
ASTM C 877
ASTM C 890
Practice for Minimum Structural Design Loading for Monolithic or Sectional Precast Concrete Water and Wastewater Structures Practice for Installation of Underground Precast Concrete Utility Structures Specification for Precast Concrete Water and Wastewater Structures Specification for Precast Reinforced Concrete Crib Wall Members Specification for Elastomeric Joint Sealants Specification for Resilient Connectors Between Reinforced Concrete Manhole Structures, Pipes, and Laterals Practice for Testing Concrete Pipe Sewer Lines by Low-Pressure Air Test Method Specification for Pigments for Integrally Colored Concrete Standard Specification for Nonreinforced Concrete Specified Strength Culvert, Storm Drain, and Sewer Pipe Specification for Joints for Concrete Pipe, Manholes, and Precast Box Sections Using Preformed Flexible Joint Sealants
ASTM C 913
ASTM C 915 ASTM C 920
ASTM C 924
ASTM C 985
Test Method for Flexural Toughness and First-Crack Strength of Fiber-Reinforced Concrete (Using Beam with Third-Point Loading) Practice for Inspection of Underground Precast Concrete Utility Structures Standard Test Method for Temperature of Freshly Mixed Portland Cement Concrete Standard Specification for Packaged Dry, HydraulicCement Grout (Nonshrink)
ASTM C 1037
Standard Specification for Fiber-Reinforced Concrete and Shotcrete Standard Specification for Admixtures to Inhibit Chloride-Induced Corrosion of Reinforcing Steel in Concrete Standard Test Method for Concrete Pipe Sewerlines by Negative Air Pressure (Vacuum) Test Method Standard Specification for Precast Concrete Septic Tanks Standard Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Concrete Cylinders
ASTM C 1582
ASTM C 1214
Standard Specification for Use of Silica Fume for Use as a Mineral Admixture in Hydraulic-Cement Concrete, Mortar, and Grout Standard Test Method for Concrete Sewer Manholes by the Negative Air Pressure (Vacuum) Test Prior to Backfill Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method) Standard Test Method for Determination of Length Change of Concrete Due to Alkali-Silica Reaction Test Method for Obtaining Average Residual-Strength of Fiber-Reinforced Concrete Standard Specification for Precast Reinforced Concrete Box Sections for Culverts, Storm Drains and Sewers
ASTM C 1478
Standard Specification for Storm Drain Resilient Connectors Between Reinforced Concrete Storm Sewer Structures, Pipes and Laterals Standard Specification for Manufacture of Precast Reinforced Concrete Three-Sided Structures for Culverts, Storm Drains Standard Test Method for Flexural Toughness of Fiber Reinforced Concrete (Using Centrally Loaded Round Panel)
ASTM C 1504
Standard Specification for Mixing Water Used in the Production of Hydraulic Cement Concrete Standard Test Method for Measurement of Solids in Water Standard Test Method for Slump Flow of SelfConsolidating Concrete Standard Specification for Precast Concrete Grease Interceptors Standard Test Method for Rubber Property— Durometer Hardness Standard Test Method for Determining the Effects of Chemical Admixtures on the Corrosion of Embedded Steel Reinforcement in Concrete Exposed to Chloride Environments
ASTM C 1603
AMERICAN WELDING SOCIETY (AWS) AWS D 1.1 AWS D 1.4 Structural Welding Code - Steel Structural Welding Code - Reinforcing Steel
CONCRETE REINFORCING STEEL INSTITUTE (CRSI) Manual of Standard Practice Placing Reinforcing Bars NATIONAL PRECAST CONCRETE ASSOCIATION (NPCA) NPCA QC Manual NPCA Selected ASTM Standards Quality Control Manual for Precast Concrete Plants ASTM Standards for Precast Concrete
PRECAST/PRESTRESSED CONCRETE INSTITUTE (PCI) MNL-120 MNL-122 PCI Design Handbook Architectural Precast Concrete
1.2 GENERAL REQUIREMENTS Precast concrete units shall be designed and fabricated by an experienced and acceptable precast concrete manufacturer. The manufacturer shall have been regularly and continuously
engaged in the manufacture of precast concrete units similar to that indicated in the project specifications or drawings for at least [ ] years. 1.3 SUBMITTALS The following items may be submitted upon request by the customer. 1.3.1 Preconstruction Submittals Submit quality control procedures established by the precast manufacturer in accordance with the NPCA Quality Control Manual for Precast Concrete Plants. 1.3.2 Shop Drawings Drawings for Standard Precast Concrete Units The drawings for standard precast concrete units shall be shop drawings furnished by the precast concrete producer for approval by the customer. These drawings shall demonstrate that the applicable industry design standards have been met. Installation and construction information shall be included on shop drawings upon request. Details of steel reinforcement size and placement as well as supporting design calculations, if appropriate, shall be included. The precast concrete units shall be produced in accordance with the approved drawings. Drawings shall indicate assumptions used in the design of standard units. It is the responsibility of the project’s engineer-of-record to verify that the design assumptions are suitable for the proposed application. Drawings for Custom-Made Precast Concrete Units The drawings for custom-made precast concrete units shall be shop drawings furnished by the precast concrete producer for approval by the customer. These drawings shall show complete design, installation, and construction information in such detail as to enable the customer to determine the adequacy of the proposed units for the intended purpose. Details of steel reinforcement size and placement as well as supporting design calculations, if appropriate, shall be included. The precast concrete units shall be produced in accordance with the approved drawings. Drawings Submitted by the Customer The customer or customer’s agent (specifier) may provide the precast concrete manufacturer with drawings for custom-made precast concrete units. Drawings shall be prepared and stamped by a licensed professional engineer. The customer or customer’s agent may consult the precast concrete manufacturer during the design process on relevant production practices that may affect the design, production, handling and installation of the custom-made precast concrete unit. The customer or customer’s agent accepts all liability associated with the use of the provided drawings. 1.3.3 Precast Concrete Unit Data Standard Precast Concrete Units For standard precast concrete units, the precast concrete producer shall supply cut sheets showing conformance to project drawings and requirements and to applicable industry design standards listed in this specification.
Proprietary Precast Concrete Units For proprietary precast concrete units, the precast concrete producer shall supply standard plans or informative literature. Supporting calculations and design details shall be available upon request. The precast concrete producer shall provide sufficient information as to demonstrate that such products will perform the intended task. Anchorage, Lifting Inserts and Devices For anchors, lifting inserts and other devices, the precast concrete producer shall provide product data sheets and proper installation instructions upon request. The Precast concrete unit dimensions and safe working load shall be clearly indicated. Accessory Items For items including, but not limited to sealants, gaskets, pipe entry connectors, steps, racks and other items installed before or after delivery, the precast concrete producer shall include proper installation instructions and relevant product data upon request. 1.3.4 Design Data Upon request, the precast concrete producer shall supply precast concrete unit design calculations and concrete mix design proportions and appropriate mix design test data. Structural design calculations shall be signed by a licensed professional engineer. 1.3.5 Test Reports Upon request, the precast concrete producer shall supply copies of material certifications and/or laboratory test reports, including mill tests and all other test data, for portland cement, blended cement, pozzolans, ground granulated blast-furnace slag, silica fume, aggregate, admixtures, and curing compound proposed for use on this project. Upon request, the precast concrete producer shall submit copies of test reports showing that the mix has been successfully tested to produce concrete with the properties specified and will be suitable for the project conditions. Such tests may include compressive strength, flexural strength, plastic or hardened air content, freeze-thaw durability, abrasion and absorption. Special tests for precast concrete items shall be clearly detailed in the specifications. Upon request, the precast concrete producer will supply copies of in-plant QA/QC inspection reports. 1.3.6 Certificates Submit quality control procedures established in accordance with NPCA Quality Control Manual for Precast Concrete Plants or verification of current NPCA Plant Certification.
1.4 DESIGN 1.4.1 Standard Precast Concrete Unit Design Design standard precast concrete units to withstand indicated design load conditions in accordance with applicable industry design standards [ACI 318, ACI 350, ASTM, ACPA Design Manual, PCI MNL-120, and AASHTO]. Design must also consider stresses induced during handling, shipping and installation in order to avoid product cracking or other handling damage. Design loads for precast concrete units shall be indicated on the shop drawings. 1.4.2 Non-Standard Precast Concrete Unit Design Design calculations and drawings of non-standard precast units shall be prepared and signed by a licensed professional engineer, and submitted for customer approval prior to fabrication. Calculations shall include the analysis of units for lifting stresses and the sizing of lifting devices. 1.4.3 Franchise Precast Concrete Units Products manufactured under franchise arrangements shall conform to all the requirements specified by the franchiser. Items not included in the franchise specification but included in this specification shall conform to the requirements in this specification. 1.4.4 Joints and Sealants Joints and sealants between adjacent units shall be of the type and configuration indicated on shop drawings meeting specified design and performance requirements. 1.4.5 Concrete Mix Design 1.4.5.1 Concrete Proportions Selection of proportions for concrete shall be based on the methodology presented in ACI 211.1 for normal weight concrete, ACI 211.2 for lightweight concrete and ACI 211.3 for no-slump concrete. The concrete proportions shall be developed using the same type and brand of cement, the same type and brand of pozzolan, the same type and gradation of aggregates, and the same type and brand of admixture that will be used in the manufacture of precast concrete units for the project. Accelerators containing calcium chloride shall not be used in precast concrete containing reinforcing steel or other embedded metal items. Upon request, the precast concrete producer shall submit a mix design for each strength and type of concrete that will be used. Submitted mix designs shall include the quantity, type, brand and applicable data sheets for all mix design constituents as well as documentation indicating conformance with applicable reference specifications. The use of self-consolidating concrete is permitted provided that mix design proportions and constituents meet the requirements of this specification. 1.4.5.2 Durability and performance requirements
1.4.5.2.1 Concrete Compressive Strength Precast concrete units shall have a 28-day compressive strength (f’c) of [ MPa, [ ] psi. 1.4.5.2.2 Water-Cement Ratio Concrete that will be exposed to freezing and thawing shall contain entrained air (see 1.4.5.2.3) and shall have water-cement ratios of 0.45 or less. Concrete which will not be exposed to freezing, but which is required to be watertight, shall have a water-cement ratio of 0.48 or less if the concrete is exposed to fresh water, or 0.45 or less if exposed to brackish water or sea water. For corrosion protection, reinforced concrete exposed to deicer salts, brackish water or seawater shall have a water-cement ratio of 0.40 or less. 1.4.5.2.3 Air Content The air content of concrete that will be exposed to freezing conditions shall be within the limits given below. Air Content % Severe Exposure Moderate Exposure 6.0 to 9.0 4.5 to 7.5 5.5 to 8.5 4.0 to 7.0 4.5 to 7.5 3.5 to 6.5 1 4.5 to 7.5 3.0 to 6.0 1-1/2 4.5 to 7.0 3.0 to 6.0 * For specified compressive strengths greater then 5000 psi, air content may be reduced 1% Nominal Maximum Aggregate Size (in) 3/8 ]
1.5 QUALITY ASSURANCE Precast concrete producer shall demonstrate adherence to the standards set forth in the NPCA Quality Control Manual for Precast Concrete Plants. The precast concrete producer shall meet requirements written in subparagraph [1.5.1 or 1.5.2.] *********************************************************************** NOTE: The use of subparagraph 1.5.1 may limit competition. Verify the availability of NPCA Certified precast concrete producers in the bidding area. Visit www.precast.org for a list of NPCA Certified precast concrete producers in your area. *********************************************************************** 1.5.1 NPCA Plant Certification The precast concrete producer shall be certified by the NPCA Plant Certification Program prior to and during production of the products for this project. 1.5.2 Qualifications, Quality Control and Inspection
1.5.2.1 Qualifications The precast concrete producer shall have been in the business of producing precast concrete units similar to those specified for a minimum of [ ] years. The precast concrete producer shall maintain a permanent quality control department or retain an independent testing agency on a continuing basis. The agency shall issue a report, signed by a licensed professional engineer, detailing the ability of the precast concrete producer to produce quality units consistent with industry standards. 1.5.2.2 Quality Control The precast concrete producer shall show that the following quality control tests are performed as required and in accordance with the ASTM International standards indicated. a. Slump: A slump test shall be performed for each 150 cu yd of concrete produced per mix design, or once a day, whichever comes first. Slump tests shall be performed in accordance with ASTM C 143. Slump flow tests on self-consolidating concrete mixes shall be performed in accordance with ASTM C 1611. b. Temperature: The temperature of fresh concrete shall be measured when slump or air content tests are made and when compressive test specimens are made in accordance with ASTM C 1064 c. Compressive Strength: At least four compressive strength specimens shall be made for each 150 cubic yards of concrete of each mix design in accordance with the following applicable ASTM standards; C 31, C 39, C 192, C 497 [noslump concrete]. d. Air Content: Tests for air content shall be made on air-entrained, wet-cast concrete for each 150 cu yd of concrete, per mix design, but not less often than once each day when air-entrained concrete is used. The air content shall be determined in accordance with either ASTM C 231 or ASTM C 173 for normal weight aggregates and ASTM C 173 for lightweight aggregates. e. Density (Unit Weight): Tests for density shall be performed a minimum of once per week to verify the yield of batch mixes. Density tests shall be performed for each 100 cu yd of lightweight concrete in accordance with ASTM C 138. Density tests shall be performed for each 100 cu yd of concrete per mix design, but not less often than once per day when volumetric batch equipment is used. *********************************************************************** NOTE: Producers utilizing self-consolidating concrete (SCC) shall conform to the quality control requirements established in the NPCA QC manual. *********************************************************************** The precast concrete producer shall submit documentation demonstrating compliance with the above subparagraphs. 1.5.2.3 Inspection The customer or customer’s agent (specifier) may place an inspector in the plant when the units covered by this specification are being manufactured. The precast concrete producer shall give notice of [ ] days prior to the time the precast concrete units will be available for plant inspection.
1.6 HANDLING, STORAGE AND DELIVERY 1.6.1 Handling Precast concrete units shall be handled and transported in a manner to minimize damage. Lifting devices or holes shall be consistent with industry standards. Lifting shall be accomplished with methods or devices intended for this purpose as indicated on shop drawings. Upon request, the precast concrete producer shall provide documentation on acceptable handling methods for the product. 1.6.2 Storage Precast concrete units shall be stored in a manner that will minimize potential damage. 1.6.3 Delivery Precast concrete units shall be delivered to the site in accordance with the delivery schedule to avoid excessive build-up of units in storage at the site. Upon delivery to the jobsite all precast concrete units shall be inspected by the customer or customer’s agent for quality and final acceptance. 1.6.4 Final Acceptance Upon final acceptance, the customer or customer’s agent acknowledges and understands the appropriate methods for handling the accepted precast concrete unit(s). Upon acceptance by the customer or customer’s agent, the precast concrete manufacture is not responsible for replacing damaged product resulting from improper handling practices on the job site.
PART 2: PRECAST CONCRETE UNITS 2.1 MANUFACTURERS The precast concrete manufacturer must meet the requirements established in section 1.5 Quality Assurance. 2.2 MATERIALS Except as otherwise specified, material shall conform to the following section. 2.2.1 Cement ASTM C 150 (Type I, II, III or V) ASTM C 595 (for Blended Cements) 2.2.2 Silica Fume ASTM C 1240 2.2.3 Fly Ash and Pozzolans ASTM C 618
2.2.4 Ground Granulated Blast-Furnace Slag ASTM C 989 2.2.5 Water ASTM C1602 [The use of reclaimed/recycled process water shall be permitted.] 2.2.6 Aggregates 2.2.6.1 Aggregate Selection *********************************************************************** NOTE: Select gradation(s) based on job requirements and constraints. The nominal maximum aggregate size should not exceed one-fifth the narrowest dimension between sides of forms, nor three-quarters the minimum clear spacing between individual reinforcing bars or wires. *********************************************************************** Aggregates shall conform to ASTM C 33. Aggregates shall not contain any substance which may be deleteriously reactive with the alkalies in the cement. Upon request, the precast concrete producer shall provide documentation indicating the aggregates are not susceptible to alkali-aggregate reaction. 2.2.6.2 Aggregates for Lightweight Concrete ASTM C 330 2.2.7 Admixtures 2.2.7.1 Air-Entraining ASTM C 260
*********************************************************************** NOTE: Air-entraining requirements may be deleted when the project is located in a nonfreezing climate or will not be exposed to freezing and thawing. However, certain product-specific ASTM Standards require the use of air-entrainment regardless of the climate. ***********************************************************************
2.2.7.2 Accelerating, Retarding, Water Reducing [Moderate to High] ASTM C 494 2.2.7.3 Pigments ASTM C 979
2.2.7.4 Corrosion Inhibitors ASTM C 1582 *********************************************************************** NOTE: ASTM C 1582 corrosion inhibitors may be specified in lieu of epoxy-coated reinforcement when corrosion protection is required. *********************************************************************** 2.2.8 Reinforcement 2.2.8.1 Reinforcing Bars *********************************************************************** NOTE: Specify ASTM A 706 reinforcing steel when welding or bending of reinforcement bars is crical. In addition, ASTM A 775 epoxy-coated reinforcing may be specified where extra reinforcement corrosion protection is required. *********************************************************************** 2.2.8.1.1 Deformed Billet-Steel ASTM A 615
2.2.8.1.2 Deformed Low-Alloy Steel ASTM A 706 2.2.8.2 Reinforcing Wire 2.2.8.2.1 Plain Wire ASTM A 82 2.2.8.2.2 Deformed Wire ASTM A 496 2.2.8.3 Welded Wire Reinforcement 2.2.8.3.1 Plain Wire ASTM A 185 2.2.8.3.2 Deformed Wire ASTM A 497 2.2.8.4 Epoxy Coated Reinforcement
2.2.8.4.1 Reinforcing Bars ASTM A 775 2.2.8.4.2 Wires and Welded Wire Reinforcement ASTM A 884 2.2.8.5 Galvanized Reinforcement ASTM A 767 2.2.9 Inserts and Embedded Metal All items embedded in concrete shall be of the type required for the intended use and meet the following standards. 2.2.9.1 Structural Steel Plates, Angles, etc. ASTM A 36 2.2.9.2 Hot-Dipped Galvanized ASTM A 152 2.2.9.3 Proprietary Items In accordance with manufacturers published literature 2.2.10 Joint Sealants and Joint Gaskets 2.2.10.1 Rubber Gaskets for Circular Concrete Sewer Pipe and Culvert Pipe ASTM C 443 2.2.10.2 External Sealing Bands for Noncircular Sewer, Storm Drain and Culvert Pipe ASTM C 877 2.2.10.3 Preformed Flexible Joint Sealants for Concrete Pipe, Manholes, and Manufactured Box Sections ASTM C 990 2.2.10.4 Elastomeric Joint Sealants ASTM C 920 2.2.11 Pipe Entry Connectors ASTM C 923 ASTM C 1478
2.2.12 Grout 2.2.12.1 Nonshrink Grout ASTM C 1107 2.2.12.2 Cementitious Grout Shall be of suitable mix design for the intended use, consisting of Portland cement, sand, and water. [Provide air entrainment for grout exposed to corrosive conditions or severe weather.]
*********************************************************************** NOTE: Air-entraining requirements may be deleted when the project is located in a nonfreezing climate or when freeze-thaw durability is not required. ***********************************************************************
2.3 MANUFACTURE Manufacture shall conform to the NPCA Quality Control Manual for Precast Concrete Plants unless specified otherwise. 2.3.1 Forms Forms for manufacturing precast concrete units shall be of the type and design consistent with industry standards and practices. They should be capable of consistently providing uniform products and dimensions. Forms shall be constructed so that the forces and vibrations to which the forms will be subjected cause no damage to the precast concrete unit. Forms shall be cleaned of concrete build-up after each use. Form release agents shall be applied according to the manufacturer’s recommendations and shall not be allowed to build up on the form casting surfaces. 2.3.2 Reinforcement Applicable ASTM International and/or ACI 318 standards for placement and splicing Cages of reinforcement shall be fabricated either by tying the bars, wires or welded wire reinforcement into rigid assemblies or by welding, where permissible, in accordance with AWS D1.4. Reinforcing shall be positioned as specified by the design and so that the concrete cover conforms to requirements. The tolerance on concrete cover shall be onethird of that specified but not more than 1/2 in. Concrete cover shall not be less than 1/2 in., unless otherwise specified. Positive means shall be taken to assure that the reinforcement does not move significantly during the casting operations. 2.3.3 Embedded Items Embedded items shall be positioned at locations specified in the design documents. Welding shall be performed in accordance with AWS D1.1 when necessary. Inserts,
plates, weldments, lifting devices and other items to be embedded in precast concrete units shall be held rigidly in place so that they do not move significantly during casting operations. 2.3.4 Concrete 2.3.4.1 Concrete Mixing Mixing operations shall produce batch-to-batch uniformity of strength, consistency, and appearance. 2.3.4.2 Concrete Placing Conventional concrete shall be deposited into forms as near to its final location as practical. Self-consolidating concrete shall be placed in a manner in which it flows and consolidates without segregation or air entrapment. The free fall of the concrete shall be kept to a minimum. Concrete shall be consolidated in such a manner that segregation of the concrete is minimized and honeycombed areas are kept to a minimum. Consolidation efforts are often not required when using self-consolidating concrete. Vibrators used to consolidate concrete shall have frequencies and amplitudes sufficient to produce well-consolidated concrete. 2.3.4.2.1 Cold Weather Concreting Recommendations for cold weather concreting are given in detail ACI 306 R. Adequate equipment shall be provided for heating concrete materials and protecting concrete during freezing or near-freezing weather. All concrete materials and all reinforcement, forms, fillers, and ground with which concrete is to come in contact shall be free from frost. Frozen materials or materials containing ice shall not be used. In cold weather the temperature of concrete at the time of placing shall not be below 45° F. Concrete that freezes before its compressive strength reaches 500 psi shall be discarded. 2.3.4.2.2 Hot Weather Concreting Recommendations for hot weather concreting are given in ACI 305 R. During hot weather, proper attention shall be given to constituents, production methods, handling, placing, protection, and curing to prevent excessive concrete temperatures or water evaporation that could impair required strength or serviceability of the member or structure. The temperature of concrete at the time of placing shall not exceed 90° F. 2.3.4.3 Concrete Curing Commence curing operations immediately following the initial set of the concrete and completion of surface finishing. *********************************************************************** NOTE: Due to the immediacy of form removal, dry-cast products have a tendency to undergo undesirable accelerated drying. Consequently, early curing periods are most critical to ensure protection from extreme temperatures and dryness. Dry-cast products must be protected from drafts and wind to prevent plastic shrinkage cracking. ***********************************************************************
2.3.4.3.1 Curing by Moisture Retention Moisture shall be prevented from evaporating from exposed surfaces until adequate strength for stripping the precast concrete unit from the forms is reached by one of the following methods: Cover with polyethylene sheets a minimum of 6 mils thick (ASTM C 171) Cover with burlap or other absorptive material and keep continually moist Use of a membrane-curing compound applied at a rate not to exceed 200 sq. ft. per gallon, or per manufacturers’ recommendations (ASTM C 309) [Surfaces that will be exposed to weather during service shall be cured as above a minimum of [ ] days. Forms shall be considered effective in preventing evaporation from the contact surfaces. If air temperature is below 50°F the curing period shall be extended.]
2.3.4.3.2 Curing with Heat and Moisture Concrete shall not be subjected to steam or hot air until after the concrete has attained its initial set. Steam, if used, shall be applied within a suitable enclosure, which permits free circulation of the steam in accordance with ACI 517.2R. If hot air is used for curing, precautions shall be taken to prevent moisture loss from the concrete. The temperature of the concrete shall not be permitted to exceed 150° F. These requirements do not apply to products cured with steam under pressure in an autoclave. 2.3.4.4 Surface Finish Unformed surfaces of wet-cast precast concrete products shall be finished as specified. If no finishing procedure is specified, such surfaces shall be finished using a strike-off to level the concrete with the top of the form. 2.3.4.4.1 Formed Non-Architectural Surfaces Surfaces shall be cast against approved forms in accordance with standard industry practices in cleaning forms, designing concrete mixes, placing and curing concrete. Normal color variations, form joint marks, small surface holes caused by air bubbles, and minor chips and spalls will be accepted. Major imperfections, excessive honeycombing or other major defects shall not be permitted. 2.3.4.4.2 Unformed Surfaces Surfaces shall be finished with a vibrating screed, or by hand with a float. Normal color variations, minor indentations, minor chips and spalls will be accepted. Major imperfections, excessive honeycombing or other major defects shall not be permitted. 2.3.4.4.3 Special Finishes Troweled, broom or other finishes shall be according to the requirements of project documents and performed per industry standards or supplier specifications.
Precast concrete producers shall submit sample finishes for approval when required by the project documents. The sample finishes shall be approved prior to the start of production. 2.3.4.4.4 Architectural Finishes Architectural finishes shall be according to the requirements of project documents and performed per industry standards or supplier specifications. Precast concrete producers shall submit sample finishes for approval when required by the project documents. Full-size mockups are recommended for the approval of architectural finishes, because color variations and surface imperfections are not always apparent on small scale samples. The sample finishes shall be approved prior to the start of production.
2.3.4.5 Stripping Precast Concrete Units From Forms Precast concrete units shall not be removed from the forms until the concrete reaches the compressive strength for stripping required by the design. If no such requirement exists, products may be removed from the forms after the final set of concrete provided that stripping damage is minimal. Stripping strengths shall be routinely measured to ensure product has attained sufficient strength for safe handling. 2.3.4.6 Patching and Repair No repair is required to formed surfaces that are relatively free of air voids and honeycombed areas, unless the surfaces are required by the design to be finished. 2.3.4.6.1 Repairing Minor Defects Defects that will not impair the functional use or expected life of a precast concrete unit may be repaired by any method that does not impair the product. 2.3.4.6.2 Repairing Honeycombed Areas When honeycombed areas are to be repaired, all loose material shall be removed and the areas cut back into essentially horizontal or vertical planes to a depth at which coarse aggregate particles break under chipping rather than being dislodged. Proprietary repair materials shall be used in accordance with the manufacturer’s instructions. If a proprietary repair material is not used, the area shall be saturated with water. Immediately prior to repair, the area should be damp, but free of excess water. A cement-sand grout or an approved bonding agent shall be applied to the chipped surfaces, followed immediately by consolidating an appropriate repair material into the cavity. 2.3.4.6.3 Repairing Major Defects Defects in precast concrete products which impair the functional use or the expected life of products shall be evaluated by qualified personnel to determine if repairs are feasible and, if so, to establish the repair procedure.
2.3.4.7 Shipping Precast Concrete Units Precast concrete units shall not be shipped until they are at least [ ] days old, unless it can be shown that the concrete strength has reached at least 75% of the specified 28-day strength, or that damage will not result, impairing the performance of the product.
PART 3: EXECUTION 3.1 INSTALLATION 3.1.1 Site Access The general contractor shall be responsible for providing adequate access to the site to facilitate hauling, storage and proper handling of the precast concrete units. 3.1.2 Installation Precast concrete units shall be installed to the lines and grades shown in the contract documents or otherwise specified. Precast concrete units shall be lifted by suitable lifting devices at points provided by the precast concrete producer. Precast concrete units shall be installed in accordance with applicable industry standards. Upon request, the precast concrete producer shall provide installation instructions. Field modifications to the product shall relieve the precast producer of liability regardless if such modifications result in the failure of the precast concrete unit. 3.1.3 Watertightness Where watertightness is a necessary performance characteristic of the precast concrete unit’s end use, watertight joints, pipe-entry connectors and inserts should be used to ensure the integrity of the entire system. 3.2 FIELD QUALITY CONTROL 3.2.1 Job Site tests When watertightness testing is required for a precast concrete structure, one of the following methods may be followed: 3.2.1.2 Vacuum Testing Prior to backfill, vacuum test system according to [ASTM C1244 (for manholes)] [ASTM C 1227 (for septic tanks)]
*********************************************************************** NOTE: Manholes and septic tanks should be tested prior to backfilling to verify the integrity of the installed product. Testing prior to backfilling facilitates quick and easy repair when required. When vacuum testing a backfilled manhole, appropriate adjustments must be made to the testing procedure to account for site conditions such as high water tables as to avoid over loading boots and connectors. Prior to vacuum testing, calculations shall be made to ensure that connectors and boots are not loaded past the design limit as indicated in ASTM C 923. *********************************************************************** 3.2.1.2 Hydrostatic Testing According to contract documents and precast concrete producer’s recommendations [or ASTM C 1227 (for septic tanks)].
*********************************************************************** This specification is intended solely for use by professional personnel who are competent to evaluate the significance and limitations of the information provided herein, and who will accept total responsibility for the application of this information. NPCA disclaims any and all responsibility and liability for the accuracy of and the application of the information contained in this publication to the full extent permitted by law. ***********************************************************************
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