SECTION 03410 — STRUCTURAL PRECAST CONCRETE


PART 1— GENERAL

1.01 DESCRIPTION

The section cover the manufacture, transportation, and erection of precast, prestressed hollowcore slabs including grouting of joints between adjacent slab units.

1.02 QUALITY ASSURANCE

The precast concrete manufacturing plant shall be certified, at time of bidding, by the Precast/Prestressed Concrete Institute, Plant Certification Program, with testing in general compliance with applicable provisions of Prestressed Concrete Institute MNL-116, Manual for Quality Control for Plants and Production of Precast Prestressed Concrete Products.

Erector must have been regularly engaged for at least 2 years in the erection of precast structural concrete similar to the requirements of this project.

All local codes plus the following specifications, standards and codes are a part of these specifications:
ACI 318 - Building Code Requirements for Reinforced Concrete.
AWS D1.1 - Structural Welding Code - Steel.
AWS D1.4 - Structural Welding Code - Reinforcing Steel.

1.03 SUBMITTALS

Submit shop drawings showing
• Setting plans locating and designating all hollowcore slab units furnished by the manufacturer, with all major openings shown and located.
• Sections and details showing connections, edge conditions and support conditions of the hollowcore slab units.
• All dead, live and other applicable loads used in the design
• Details to indicate quantities, location and type of reinforcing steel and prestressing strands.
• Dimensions and special finishes.

Design deviations will be permitted only after the Architect/Engineer’s written approval of the manufacturer’s proposed design supported by complete design calculations and drawings. Design deviations shall provide an installation equivalent to the basic intent without incurring additional cost to the Owner.

1.04 PRODUCT DELIVERY, STORAGE, AND HANDLING

Hollowcore slab units shall be lifted and supported during manufacturing, stockpiling, transporting, and erection operations only at the lifting or supporting point, or both, as shown on the shop drawings, and with approved lifting devices. Lifting inserts shall have a minimum safety factor of 4. Exterior lifting hardware shall have a minimum safety factor of 5.

Transportation, site handling, and erection shall be performed with acceptable equipment and methods, and by qualified personnel.

Store all units off ground. Place so that identification marks are discernible and that lifting devices are accessible and undamaged. Separate stacked members by battens across full width of each slab unit. Do not use upper member of stacked tier as storage area for shorter member or heavy equipment.

Set aside, sort, and protect substandard and damaged precast concrete products. Provide for delivery to or collection by alternative end user, e.g., for secondary use as foot bridges or stream bank reinforcement.


PART 2 — PRODUCTS

2.01 MATERIALS

Portland Cement: ASTM C150 - Type I or III
Aggregates: ASTM C33 or C330.
Admixtures: ASTM C494. Do not use calcium chloride, chloride ions or other salts.
Water: Potable or free from foreign materials harmful to concrete and embedded steel.
Reinforcing Steel: Bars: Deformed Billet Steel: ASTM A615, grade 40 or 60
Prestressing Strand: Uncoated, 7-Wire, Stress-Relieved Strand: ASTM A416, grade 250K or 270K.
Welded Studs: In accordance with AWS D1.1.
Structural Steel Plates and Shapes: ASTM A36.
Grout: Mixture of not less than one part Portland Cement to three parts fine sand and water sufficient for placement and hydration.
Caulking: Non-shrinking, nonstaining thermoplastic putty.
Bearing Strips: Tempered Hardboard.

2.02 CONCRETE MIXES

28 day compressive strength: Minimum of 5,000 psi.
Release strength: Minimum of 3,000 psi.

2.03 MANUFACTURE

Manufacturing procedures and tolerances shall be in compliance with PVI MNL - 116.

Manufacturer shall provide for those openings 10 in. or larger, round or square as shown on the structural drawings. Other openings shall be located and field drilled or cut by the trade requiring them after the hollowcore slab units have been erected. Openings and/or cutting of prestressing strand shall be approved by Architect/Engineer and manufacturer before drilling or cutting.

Patching will be acceptable providing the structural adequacy of the hollowcore unit is not impaired.


PART 3 — EXECUTION

3.01 GENERAL

The General Contractor shall be responsible for:
• Providing suitable access to the building, proper drainage and firm level bearing for the hauling and erection equipment to operate under their own power.
• Providing true, level bearing surfaces on all field placed bearing walls and other field placed supporting members.
• All pipes, stacks, conduits, and other such items shall be stubbed off at a level lower than the bearing plane of the prestressed concrete products until after the latter are set.

3.02 ERECTION

Installation of hollowcore slab units shall be performed by the manufacturer or a competent erector. Set bearing strips, where required. Lift units by means of suitable lifting devices at points provided by the manufacturer and set level and square, keeping units tight and at right angles to bearing walls. Temporary shoring and bracing, if necessary, shall comply with manufacturer’s recommendations.

3.03 GROUTING AND CAULKING

Fill keys with grout. Remove any grout that may seep through to ceiling below before it hardens. Provide suitable end cap or dam in voids at slab ends (where shown on Drawings) as required.

Apply caulk uniformly, using no more than required to fill the joints.

Delete below if not required.
For areas where slab voids are to be used as electrical raceways or mechanical ducts provide a taped butt joint at end of slabs, making sure the voids are aligned.

Delete below if not required.
3.04 FIELD WELDING

Field welding is to be done by certified welders using equipment and materials compatible to the base material.

3.05 ATTACHMENTS

Subject to approval of the Architect/Engineer, hollowcore slab units may be drilled or “shot” provided no contact is made with the prestressing steel. Should spalling occur, it shall be repaired by the trade doing the drilling or the shooting.

3.06 CLEANING

Neatly and fully finish. Remove rubbish attributed to this work. Remove all surplus materials for reuse or recycling.


END OF SECTION 03410


STRUCTURAL PRECAST CONCRETE 03410-#
courtesy of Design Coalition, Architects. , Madison, Wisconsin, USA ~~ www.designcoalition.org