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HomeMy WebLinkAbout73SECTION 03410 PRECAST CONCRETE HOLLOW CORE SLABS PART 1 GENERAL 1.1 This Specification is based on a guide specification developed jointly by PCI, Gensler and the American Institute of Architects (AIA), Master Systems publishers of MASTERSPEM. 1.2 RELATED DOCUMENTS A. Drawings and general provisions of Contract, including General and Supplementary Conditions and Division 1 Specification Sections, apply to this Section. 1.3 SUMMARY A. This section includes the performance criteria, materials, production, and erection of structural precast and precast, prestressed concrete for the entire project. The work performed under this section includes all labor, material, equipment, related services, and supervision required for the manufacture and erection of the structural precast and precast, prestressed concrete work shown on the contract drawings. B. This Section includes the following: 1. Hollow -core slab units 1.4 PERFORMANCE REQUIREMENTS A. Structural Performance: Provide structural precast concrete units and connections capable of supporting the design loads indicated on drawings. B. Design framing system and connections to maintain clearances at openings, to allow fabrication and construction tolerances, to accommodate live load deflection, shrinkage and creep of primary building structure, and other building movements. Member deflections shall meet the limits of ACI 318. 1.5 RELATED SECTIONS A. Section 03300 - Cast -in -Place Concrete B. Section 05120 - Structural Steel 1.6 SUBMITTALS A. General: Submit the following in accordance with Conditions of Contract and Division 1 Specification Sections. 1. Product data for proprietary materials and items, as requested by Architect, or Engineer. 2. Concrete mix designs. 3. Laboratory test reports for concrete materials and mix design test. 4. Materials certificates in lieu of materials laboratory test reports when permitted by Engineer. Materials certificates shall be signed by manufacturer and Contractor, certifying that each material item complies with or exceeds specified requirements. Provide certification from admixture manufacturers that chloride content complies with specification requirements. 5. Comprehensive engineering design signed and sealed by a professional engineer responsible for its preparation and licensed in the state in which the project is located 6. Erection Drawings: Detail fabrication and installation of structural precast concrete units. Indicate member locations, plans, elevations, dimensions, shapes, cross sections, openings, extent and location of each finish, connections, support conditions and types of reinforcement, including special reinforcement. a) Indicate welded connections by AWS standard symbols. Detail loose and cast -in hardware, lifting and erection inserts, connections, and joints. b) Indicate locations, tolerances and details of anchorage devices to be embedded in or attached to structure or other construction. c) Indicate plans and/or elevations showing member locations with all openings larger than 10 in shown and located. d) Indicate location of each structural precast concrete unit by some identification mark placed on unit. e) Indicate relationship of structural precast concrete members to adjacent materials. 7. Estimated cambers for floor slabs receiving cast -in-place topping. 8. Indicate shim sizes and grouting sequence. 9. Design Modifications: a) If design modifications are necessary to meet the performance requirements and field conditions, notify the Architect and Engineer immediately and submit design calculations and drawings. Do not adversely affect the appearance, durability or strength of units by modifying details or materials. Maintain the general design concept when altering size of members and alignment. 10. Qualification Data: Include list of completed projects with project names and addresses, names and addresses of architects, engineers and owners. B. Review of submittals is only for general conformance with the design concept and project requirements and does not imply approval of any variance from the contract documents. Neither the Architect nor the Engineer checks dimensions or quantities. C. Neither the Architect nor the Engineer will review items relating to means and methods of construction. 1. The contractor is solely responsible for the means and methods of construction. The contractor shall take all necessary precautions to insure safe working conditions and provide for the public safety during all stages of their work. 1.7 REFERENCED STANDARDS A. Codes and Standards: Comply with provisions of following codes, specifications, and standards, except where more stringent requirements are shown or specified: 1. ACI 301 "Specification for Structural Concrete for Buildings" 2. ACI 304 "Recommended Practice for Measuring, Mixing, Transporting and Placing Concrete" 3. ACI 305 "Hot Weather Concreting" 4. ACI 306 "Cold Weather Concreting" 5. ACI 318, "Building Code Requirements for Structural Concrete" 6. Concrete Reinforcing Steel Institute (CRSI), "Manual of Standard Practice" 1.8 QUALITY ASSURANCE A. Regulatory Requirements: Contractor shall comply with applicable codes and regulations of the governmental agencies having jurisdiction. Where those requirements conflict with these specifications, comply with the more stringent provisions. B. Fabricator Qualifications: Show evidence of competence in precast concrete construction. Workers shall be proficient in production operations and shall be under the direct supervision of a competent superintendent/foreman at all times. C. Professional Engineer Qualifications: A professional engineer who is legally qualified to practice in the jurisdiction where the project is located and is experienced in providing engineering services of the kind indicated. Engineering services are defined as those performed for installations of structural precast concrete that are similar to those indicated for this Project in material, design, and extent D. Erector Qualification: An erector with a minimum of 2 years of experience who has completed structural precast concrete work similar in material, design, and extent to that indicated for this Project and whose work has resulted in construction with a record of successful in-service performance and who meets the following requirements: E. Qualifications for Welding: 1. Qualify welding processes and welding operators in accordance with ANSI/AWS D1.4. 2. Provide certification that welders to be employed in the work have satisfactorily passed AWS qualification test within the previous 12 months. F. Quality -Control Standard: For manufacturing procedures and testing requirements and quality -control recommendations for types of units required, comply with PCI MNL 116, "Manual for Quality Control for Plants and Production of Structural Concrete Products." 1. Comply with camber and dimensional tolerances of PCI MNL 135, "Tolerance Manual for Precast and Prestressed Concrete Construction." 2. Concrete Testing Service: The General Contractor shall engage a testing laboratory to perform material evaluation tests. Refer to Division 1 Specification Sections. 3. Materials and installed work, which do not conform to the specified requirements, shall be corrected/replaced at Contractors expense. G. Preinstallation Conference: Conduct conference at Project site to comply with requirements in Division 1 Section "Project Management and Coordination." 1.9 PRODUCT DELIVERY, STORAGE AND HANDLING A. Store units with adequate dunnage and bracing and protect units to prevent contact with soil, staining, and to prevent cracking, distortion, warping or other physical damage. B. Store units, unless otherwise specified, with dunnage across full width of each bearing point. C. Place stored units so identification marks are clearly visible, and product can be inspected. D. Deliver all structural precast concrete units to the project site in such quantities and at such times to assure compliance with the schedule and proper setting sequence to ensure continuity of installation. E. Handle and transport units in a position consistent with their shape and design in order to avoid excessive stresses that would cause cracking or damage. F. Lift and support units only at designated points shown on the Shop Drawings. G. Place dunnage of even thickness between each unit. H. Furnish loose connection hardware and anchorage items to be embedded in or attached to other construction without delaying the Work. Provide setting diagrams, templates, instructions, and directions, as required, for installation. PART 2 PRODUCTS 2.1 FORM MATERIALS A. MOLD MATERIALS 1. Molds: Rigid, dimensionally stable, non-absorptive material, warp and buckle free, that will provide continuous and true precast concrete surfaces within fabrication tolerances indicated; nonreactive with concrete and capable of producing required finish surfaces. 2. Mold -Release Agent: Commercially produced liquid -release agent that will not bond with, stain or adversely affect precast concrete surfaces and will not impair subsequent surface or joint treatments of precast concrete. 2.2 REINFORCING MATERIALS A. Reinforcing Bars: ASTM A 615, Grade 60, deformed. 1. Refer to drawings for types of reinforcing required. B. Steel Wire: ASTM A-82, plain, cold -drawn steel 2.3 PRESTRESSING TENDONS A. Prestressing Strand: ASTM A 416/A 416M, Grade 250 (Grade 1720) or Grade 270 (Grade 1860), uncoated, 7 -wire, low -relaxation strand or ASTM A 886/A 886M, Grade 270 (Grade 1860), Indented, 7 -wire, low -relaxation strand (including supplement). 2.4 CONCRETE MATERIALS A. Portland cement: ASTM C 150, Type I 1. Use one brand of cement throughout project unless otherwise acceptable to Engineer. B. Normal Weight Aggregates: ASTM C 33 and as herein specified. Provide aggregates from a single source for exposed concrete. 1. Do not use fine or coarse aggregates containing substances that cause spoiling, staining or in any other way detract from the aesthetics or structural performance of the finished panel. C. Water. Potable, and free of substances deleterious to concrete or reinforcement. D. Admixtures, General: 1. Provide admixtures for concrete that contain not more than 0.1 percent chloride ions. 2. Admixtures shall be used at the discretion of the fabricator. E. Air -Entraining Admixture: ASTM C 260, certified by manufacturer to be compatible with other required admixtures. F. Water -Reducing Admixture: ASTM C 494, Type A G. High -Range Water -Reducing Admixture (Super Plastici7er): ASTM C 494, Type F or Type G H. Water -Reducing, Accelerating Admixture: ASTM C 494, Type E I. Water -Reducing, Retarding Admixture: ASTM C 494, Type D 2.5 RELATED MATERIALS A. Curing compound: 1. Liquid type membrane forming curing compound complying with ASTM C309, Type I and I D, class B. 2.6 MISCELLANEOUS METALS A. Provide plates, angles and other steel items shown on drawings that are cast in precast member,. 1. Metals shall conform to the requirements of section 5120 2.7 PROPORTIONING AND DESIGN OF MIXES A. Prepare design mixes for each type and strength of concrete by either laboratory trial batch or field experience methods as specified in ACI 301. If supplier c;looses trial batch method, use an independent testing facility acceptable to Structural Engineer for preparing and reporting proposed mix designs. B. Submit written reports to General Contractor and Engineer cf each proposed mix for each class of concrete at least 15 days prior to start of work. Do not begin concrete production until proposed mix designs have been reviewed. C. Compressive Strength (f'c) at 28 Days: minimum 5000 psi. Release Strength: as required by design 2.8 ADMIXTURES A. General: All admixtures shall be used in compliance with manufacturer recommendations. All admixtures are subject to review by the Engineer. 2.9 CONCRETE MIXING A. Ready -Mix Concrete: Comply with requirements of `.STM C 94, and as specified. 1. When air temperature is between 85 deg F (30 deg C) and 90 deg F (32 deg C), reduce mixing and delivery time from 1-1/2 hours to 60 minutes, and when air temperature is above 90 deg r (32 deg C), reduce mixing and delivery time to 45 minutes. 2.10 FABRICATION A. Cast -in Anchors, Inserts, Plates, Angles, and Other Anchorage Hardware: Fabricate anchorage hardware with sufficient anchorage and embedment to comply with design requirements. Accurate.y position for attachment of loose hardware and secure in place during precasting operations. Locate anchorage hardware where it does not affect position of main reinforcement or concrete placement. Do not relocate bearing plates in units unless approved by Architect. B. Weld headed studs and deformed bar anchors used for c.ichorage according to AWS 01.1 and AWS C5.4, "Recommended Practices for Stud Welding." C. Fumish loose steel plates, clip angles, seat angles, anchors, dowels, cramps, hangers, cnd other hardware shapes for securing precast concrete units to supporting and adjacent construction. D. Cast -in reglets, slots, holes, and other accessories in structural precast concrete units as indicated on contract drawings. E. Cast -in openings larger than 10 inches (250 mm) in any dimension. Do not drill or cut openings or prestressing strand without approval of Engineer. F. Reinforcement: Comply with recommendations in PCI MNL 116 for fabrication, placing, and supporting reinforcement. G. Clean reinforcement of loose rust and mill scale, earth, and other materials that reduce or destroy the bond with concrete. When damage to epoxy coated reinforcing exceeds limits specified ASTM A775/A775M repair with patching material compatible with coating material. Epoxy coat bar ends after cutting. H. Accurately position, support, and secure reinforcement against displacement during concrete -placement and consolidation operations. Locate and support reinforcement by metal or plastic &..airs, runners, bolsters, spacers, hangers, and other devices for spacing, supporting, and fastening reinforcing bars and welded wire fabric in place according to PCI MNL 116. I. Place reinforcing steel and prestressing steel to maintain a minimum 3/4 -inch concrete cover. Increase cover requirements in accordance with ACI 318 when units are exposed to corrosive environment or severe exposure conditions. Arrange, space, and securely tie bars and bar supports to hold reinforcement in position while placing concrete. Direct wire tie ends away from finished, exposed concrete surfaces. J. Install welded wire fabric in lengths as long as practicable. Lap adjoining pieces at least one full mesh and wire tie laps. Offset laps of adjoining widths to prevent continuous laps in either direction. K. Reinforce structural precast concrete units to resist handling, transportation, and erection stresses. L. Prestress tendons for structural precast concrete units by pretensioning methods. Comply with PCI MNL 116. 1. Delay detensioning of precast prestressed concrete units until concrete has reached its minimum design release compressive strength as established by test cylinders cured under the some conditions as concrete member. M. Recess strand ends and anchorages exposed to view a minimum of 1/2 inch (12 mm), fill with grout and sack rub surface. N. Cold -Weather Placing: Comply with provisions of ACI 306 and as follows. Protect concrete work from physical damage or reduced strength that could be caused by frost, freezing actions, cr low temperatures. 0. Hot -Weather Placing: When hot weather conditions exist that would seriously impair quality and strength of concrete, place concrete in compliance with ACI 305 and as herein specified. P. Identify pickup points of precast concrete units and orientation in structure with permanent markings, complying with markings indicated on Shop Drawings. Imprint or permanently mark casting date on each precast concrete unit on a surface that will not show in finished structure. Q. Cure concrete, according to requirements in PCI MNL 116, by moisture retention without heat or by accelerated heat curing using live steam or radiant heat and moisture. Cure units until the compressive strength is high enough to ensure that stripping does not have an effect on the performance or appearance of the final product. 2.11 FINISHES A. Standard Grade: Normal plant -run finish produced in forms that impart a ,mooth finish to concrete. Surface holes smaller than 1/2 inch caused by air bubbles, normal color variations, form joint marks, and minor chips and spalls will are acceptable. Fill air holes greater than 1/4 inch in width that occur in high concentration (more than one per 2 in.']). Major or unsightly imperfections, honeycombs, or structural defects are not permitted. PART 3 - EXECUTION 3.1 PREPARATION A. Deliver anchorage devices that are embedded in or attached to the building structural frame or foundation before start of such work. Provide locations, setting diagrams, and templates for the proper installation of each anchorage device. 3.2 EXAMINATION A. Examine supporting structure or foundation and conditions for compliance with requirements for installation tolerances, true and level bearing surfaces, and other conditions affecting performance. Proceed with installation only after unsatisfactory conditions have been corrected. 3.3 ERECTION A.Install loose clips, hangers, bearing pads, and other accessories required for connecting structural precast concrete units to supporting members and backup materials. B. Erect precast concrete level, plumb and square within the specified allowable tolerances. Provide temporary structural framing, supports and bracing as required to maintain position, stability, and alignment of units until permanent connections are completed. C.Install temporary steel or plastic spacing shims or bearing pads as precast concrete units are being erected. Tack weld steel shims to each other to prevent shims from separating. D. Maintain horizontal and vertical joint alignment and uniform joint width as erection progresses. E. Remove projecting lifting devices and use sand -cement grout to fill voids within recessed lifting devices flush with surface of adjacent precast concrete surfaces when recess is exposed. F. Provide and install headers of cast -in-place concrete or structural steel shapes for openings larger than one slab width according to hollow -core slab unit fabricators written recommendations. G. Connect structural precast concrete units in position by bolting, welding, grouting, or as otherwise indicated on approved Erection Drawings. Remove temporary shims, wedges, and spacers as soon as practical after connecting and/or grouting are completed. H. Welding: Comply with applicable AWS D1.1 and AWS D1.4 requirements for welding, welding electrodes, appearance, quality of welds, and methods used in correcting welding work. 1. Protect structural precast concrete units and bearing pads from damage by field welding or cutting operations and provide noncombustible shields as required. 2. Clean weld affected metal surfaces with chipping hammer followed by brushing then apply a minimum 0.004 -inch thick coat of galvanized repair paint to galvanized surfaces in conformance with ASTM A 780. I. Grouting or Dry Packing Connections and Joints: Erection drawings shall indicate joints to be grouted and any critical grouting sequences. Grout open spaces at keyways, connections and joints where required or indicated. Retain grout in place until hard enough to support itself. Pack spaces with stiff grout material, tamping until voids are completely filled. Place grout to finish smooth, level, and plumb with adjacent concrete surfaces. Fill joints completely without seepage to other surfaces. Promptly remove grout material from exposed surfaces before it affects finishes or hardens. Keep grouted joints damp for not less than 24 hours after initial set. J. Slab Ends (where shown on Drawings) and where ends are left exposed: Provide suitable end cap or dam in voids as required. 3.4 ERECTION TOLERANCES A. Erect structural precast concrete units level, plumb, square, true, and in alignment without exceeding the noncumulative erection tolerances of PCI MNL 135. Level out variations between adjacent members by jacking, loading, or any other feasible method as recommended by the manufacturer and acceptable to the Architect. 3.5 FIELD QUALITY CONTROL A. Testing: Owner will engage a qualified independent testing and inspecting agency to perform field tests and inspections. B. Field welds will be subject to visual inspections and non-destructive testing in accordance with ASTM E 165 or ASTM E 709. C. Testing agency will report test results promptly and in writing to Contractor and Architect. D. Repair or remove and replace work that does not comply with specified requirements. E. Additional testing and inspecting, at Contractor's expense, will be performed to determine compliance of corrected work with specified requirements. 3.6 REPAIRS A. Repairs will be permitted provided structural adequacy, serviceability and durability of units and appearance are not impaired. 1. Contractor shall obtain prior approval for all repairs for Architect. B. Architect and Engineer shall have final approval of repaired units. Repaired unit that are not acceptable to the Architect or Engineer shall be removed and replaced at no cost to the owner. 3.7 CLEANING A. Clean mortar, plaster, fireproofing, weld slag, and any other deleterious material from concrete surfaces and adjacent materials immediately. B. Clean exposed surfaces of precast concrete units after erection and completion of joint treatment to remove weld marks, other markings, dirt, and stains. C. Perform cleaning procedures, if necessary, according to precast concrete fabricator's recommendations. Clean soiled precast concrete surfaces with detergent and water, using stiff fiber brushes and sponges, and rinse with clean water. Protect other work from staining or damage due to cleaning operations. D. Do not use cleaning materials or processes that could change the appearance of exposed concrete finishes or damage adjacent materials. 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