General Construction Specifications
PART 1 - GENERAL
01 SECTION INCLUDES
A. Formwork for cast-in-place concrete, with shoring, bracing and anchorage.
B. Openings and installation of imbeds for other work.
C. Formwork accessories.
D. Stripping Forms.
02 REFERENCE STANDARDS
A. Abbreviations and acronyms for reference standards are defined in Section 01090.
B. ACI 301 - Specifications for Structural Concrete for Buildings.
C. ACI 347 - Recommended Practice for Concrete Formwork.
D. ACI 350 - Concrete Sanitary Engineering Structures.
E. PS 1 - Construction and Industrial Plywood.
F. ASTM D994 - Expansion Joint Filler.
G. ASTM D2103 - Moisture Barrier.
1.02 QUALITY ASSURANCE
A. Construct and erect concrete formwork in accordance with ACI 301 and ACI 347.
B. Design of formwork, shoring and its removal is the Contractor's responsibility. Do not remove shores earlier than recommended by ACI 301 and ACI 347.
1.03 SUBMITTALS
A. Submit the following in accordance with Section 01340.
B. Manufacturer's letter of certification that form release agents will not affect the bond of waterproofing materials, flooring products or any other adhered product.
C. Shop drawings indicating pertinent dimensions, materials and arrangement of joints and ties.
D. Engineer's review is for general conformance with plans and specifications. Design of formwork for structural stability and efficiency is Contractor's responsibility.
1.04 DELIVERY, STORAGE AND HANDLING
A. Deliver forms and accessories to jobsite in accordance with Section 01610.
1. Accessory items shall be in manufacturer's original, unopened packaging.
B. Store and protect materials in accordance with Section 01620 and manufacturer's recommendations.
PART 2 - PRODUCTS
03 FORM MATERIALS
A. Forms for Unexposed Concrete: Construct with plywood, lumber, metal or other acceptable material. Use lumber dressed on at least two edges and one side for tight fit.
B. Forms for Exposed Concrete: Unless otherwise indicated, construct formwork for exposed concrete surfaces with plywood, metal, metal-framed plywood faced or other acceptable panel-type materials, to provide continuous, straight, smooth, exposed surfaces. Furnish in largest practicable sizes to minimize number of joints and to conform to joint system shown on drawings. Provide form material with sufficient thickness to withstand pressure of newly-placed concrete without bow or deflection.
1. Use plywood complying with U.S. Product Standard PS-1 "B-B (Concrete Form) Plywood", Class I, Exterior Grade or better, mill-oiled and edge-sealed, with each piece bearing legible inspection trademark.
04 FORMWORK ACCESSORIES
A. Form Ties: Factory-fabricated, adjustable-length, removable or snapoff metal form ties, designed to prevent form deflection, and to prevent spalling concrete surfaces upon removal. Ties should leave no metal within 1-1/2" of the surface, and should provide a cone shaped depression at least 1-1/2" deep to allow filling and patching.
B. Waterstops: Volclay "Waterstop RX101" bentonite clay-based material with primer as recommended by manufacturer, refer to Section 07132.
C. Expansion Joint Filler: Asphalt impregnated premolded fiberboard expansion joint filler per ASTM D-1751.
1. Size: 1/2" thick by full thickness of slab or joint unless otherwise indicated.
D. Moisture Barrier: Polyethylene sheet not less than 6 mils thick and complying with requirements of ASTM D2103, Type 13000; placed over prepared base material where indicated.
E. Form Release Agent: Commercial formulation form-coating compound which will not stain concrete, absorb moisture, or impair adhesion or color characteristics of subsequent coatings intended for use on concrete. Compound shall be non-toxic after 30 days. Form coatings used inside clearwells must be approved by waterproofing manufacturer.
PART 3 - EXECUTION
05 INSPECTION
A. Verify lines, levels and measurements before proceeding with formwork.
06 FORMS
A. Design, erect, support, brace and maintain formwork to support vertical and lateral loads that might be applied until such loads can be supported by concrete structure. Construct formwork so concrete members and structures are of correct size, shape, alignment, elevation and position. Design and construction of formwork is the responsibility of the Contractor.
B. Construct forms complying with ACI 347. Provide for openings, offsets, sinkages, keyways, recesses, moldings, rustications, reglets, chamfers, blocking, screeds, bulkheads, anchorages and inserts, and other features required in work. Use selected materials to obtain required finishes. Solidly butt joints and provide back-up at joints to prevent leakage of cement paste.
C. Fabricate forms for easy removal without hammering or prying against concrete surfaces. Provide crush plates or wrecking plates where stripping may damage cast concrete surfaces. Provide top forms for inclined surfaces where slope is too steep to place concrete with bottom forms only. Kerf wood inserts for forming keyways, reglets, recesses, and the like, to prevent swelling and for easy removal.
D. Provide temporary openings where interior area of formwork is inaccessible for cleanout, for inspection before concrete placement, and for placement of concrete. Securely brace temporary openings and set tightly to forms to prevent loss of concrete mortar. Locate temporary openings on forms at inconspicuous locations.
E. Chamfer exposed corners and edges as indicated, using wood, metal, PVC or rubber chamfer strips fabricated to produce uniform smooth lines and tight edge joints.
F. Provisions for Other Trades: Provide openings in concrete formwork to accommodate work of other trades. Determine size and location of openings, recesses and chases from trades providing such items. Accurately place and securely support items built into forms.
G. Cleaning and Tightening: Thoroughly clean forms and adjacent surfaces to receive concrete. Remove chips, wood, sawdust, dirt or other debris just before concrete is placed. Retighten forms and bracing after concrete placement if required to eliminate mortar leaks and maintain proper alignment.
H. Tolerances: Construct formwork to maintain tolerances in accordance with ACI 301.
07 PREPARATION OF FORM SURFACES
A. Coat contact surfaces of forms with a form-coating compound before reinforcement is placed.
B. Thin form-coating compounds only with thinning agent of type, and in amount, and under conditions of form-coating compound manufacturer's directions. Do not allow excess form-coating material to accumulate in forms or to come into contact with concrete surfaces against which fresh concrete will be placed. Apply in compliance with manufacturer's instructions.
C. Coat steel forms with a non-staining, rust-preventative form oil or otherwise protect against rusting. Rust-stained steel formwork is not acceptable.
D. During cold weather, remove ice and snow from forms. Do not use de-icing salts. Do not use water to clean out completed forms, unless formwork and construction proceed within heated enclosure. Use compressed air to remove foreign matter.
08 INSTALLATION OF EMBEDDED ITEMS
A. General: Set and build into work anchorage devices and other embedded items required for other work that is attached to, or supported by, cast-in-place concrete. Use setting drawings, diagrams, instruction and directions provided by suppliers of items to be attached thereto.
B. Edge Forms and Screed Strips for Slabs: Set edge forms or bulkheads and intermediate screed strips for slabs to obtain required elevations and contours in finished slab surface. Provide and secure units sufficiently strong to support types of screed strips by use of strike-off templates or accepted compacting type screeds.
09 SHORES AND SUPPORTS
A. Comply with ACI 347 for shoring and reshoring and as herein specified.
B. Remove shores and reshore in a planned sequence to avoid damage to partially cured concrete. Locate and provide adequate reshoring to safely support work without excessive stress or deflection.
C. Keep reshores in place a minimum of 15 days after placing upper tier, and longer if required, until concrete has attained 85 percent of its required 28-day strength and heavy loads due to construction operations have been removed.
010 REMOVAL OF FORMS
A. Formwork not supporting weight of concrete, such as sides of beams, walls, columns, and similar parts of the work, may be removed after cumulatively curing at not less than 50 degrees F. for 24 hours after placing concrete, provided concrete is sufficiently hard to not be damaged by form removal operations, and provided curing and protection operations are maintained.
B. Formwork supporting weight of concrete, such as beam soffits, joints, slabs and other structural elements, may not be removed in less than 7 days and until concrete has attained 70 percent of design minimum compressive strength at 28-days. Determine potential compressive strength of inplace concrete by testing field-cured specimens representative of concrete location or members.
C. Reshore structural members due to design requirements or construction conditions to permit successive construction.
D. Remove formwork progressively so no unbalanced loads are imposed on structure.
E. Do not damage concrete surfaces during form removal.
011 RE-USE OF FORMS
A. Clean and repair surfaces of forms to be re-used in work. Split, frayed, delaminated or otherwise damaged form facing material will not be acceptable for exposed surfaces. Apply new form coating compound as specified for new formwork.
B. When forms are intended for successive concrete placement, thoroughly clean surfaces, remove fins and laitance, and tighten forms to close joints. Align and secure joint to avoid offsets. Do not use "patched" forms for exposed concrete surfaces, except as acceptable to Engineer.
END OF SECTION
