49-03100 Concrete Formwork.pdf

SECTION 03100

CONCRETE FORMWORK DIVISION 3

West Branch Regional Authority 03100-1 January 2026 Route 54 Sanitary Sewer Extension Project Concrete Formwork Contract No. WB-1

PART 1 - GENERAL

1.01 DESCRIPTION OF WORK

A. Scope

1. The work covered under this section shall consist of providing all plant, labor, and material required to furnish and install all formwork for concrete work, as set forth on the Drawings and in accordance with this section of the Specifications.

B. Related Work Specified Elsewhere in the Contract Documents

1. Section 03200: Concrete Reinforcement.

2. Section 03300: Cast-In-Place Concrete.

1.02 QUALITY ASSURANCE

A. Reference Standards and Specifications

1. The Contractor shall comply with the practices and standards of the following specifications:

a. ACI 301: Specifications for Structural Concrete

b. ACI 347: Recommended Practice for Concrete Formwork

1.03 SUBMITTALS

A. Shop Drawings and Product Data

1. Refer to requirements in Section 01340: Shop Drawings, Product Data and

Samples.

PART 2 - PRODUCTS

2.01 MATERIALS

A. The type, shape, size, quality, and strength of all materials of which forms are made shall be subject to the approval of the Engineer.

B. Form sheathing for exposed surfaces may be composed of tongue-and-groove lumber, shiplap, plywood, concrete form board, or steel. Steel lining on wood lagging will not be permitted. Tongue and groove shiplap when used shall conform to the American Lumber Standards for No. 2 boards. Plywood used for sheathing or lining shall be Grade B-B, exterior or better, as described in U.S. Product Standard PSl-74 of the American Plywood Association. The forms used shall produce a concrete surface with “abrupt” irregularities less than 1/32 inch and gradual irregularities less than 1/16 inch in four (4) feet.

C. All lumber used for forms shall be thoroughly cleaned and treated with an approved form

West Branch Regional Authority 03100-2 January 2026 release agent. Lumber used in forms for exposed surfaces shall be dressed and matched to a uniform thickness and shall be free from loose knots or other defects. For unexposed surfaces and rough work, undressed lumber free of nails and clean of hardened concrete or other foreign material may be used.

D. Form lining having a glazed, watertight surface will not be permitted for exposed concrete surfaces or for surfaces where severe weathering or sever hydraulic cavitation or erosion may be experienced.

E. All form ties will be a type which does not leave an open hole through the concrete and which permits neat and solid patching at every hole. Embedded metal rods of a design approved by the Engineer shall be used for internal form ties. They shall be so designed and arranged that when the forms are removed, no metal shall be within two (2) inches of any concrete surface. Wire ties will not be permitted where the concrete surface will be exposed to weathering and where discoloration will be objectionable. The ties used shall be manufactured in such a way that installation will not necessitate a hole in the form larger than the tie rod. Waterstops are required for all form ties used in wall construction of all structures designed to hold water. Ordinary wire ties and ties that require removal from the concrete will not be permitted.

F. All form sealers will be of first quality of their respective kinds and shall be approved by the

Engineer.

PART 3 - EXECUTION

3.01 CONSTRUCTION OF FORMS

A. All formwork shall be designed and constructed in accordance with ACI 301 and ACI 347, except as otherwise noted in the Specifications and on the Drawings.

B. Forms shall conform to the shapes, lines, grades, and dimensions of the concrete as indicated on the Drawings.

C. The Contractor will exercise particular care in the layout of forms to avoid the necessity for cutting of concrete after it is in place; make proper provision for all openings, offsets, recesses, anchorage, blocking, embedded items and other features of the Work, as shown on the Drawings or required for work of other contractors; and do all cutting and repairing of forms required to permit such installation. The Contractor will carefully examine the Drawings and Specifications and consult with other contractors as required relative to provision for openings, reglets, chases, and other items in the forms. The Contractor will set all required sleeves, frames, angles, grilles, bolts, inserts, and other such items required to be anchored in the concrete before the concrete is placed.

D. The forms will be properly braced and tied together so as to maintain position and shape during and after placing concrete and to ensure safety to personnel. Forms shall be sufficiently tight to prevent leakage of mortar. Forms will be properly spaced apart with spreaders or spreader ties that provide accurate spreading. The Contractor will construct all bracing, supporting members, and centering of ample size and strength to safely carry

West Branch Regional Authority 03100-3 January 2026 all dead and live loads to which they may be subjected without deflection in any form member in excess of one (1) in 360 where the concrete surfaces are exposed or in excess of one (1) in 240 elsewhere.

E. All forms shall be constructed so that they can be removed without hammering or prying against the concrete. All exposed joints and edges shall have a three-quarter (3/4) inch chamfer and suitable molding shall be placed to bevel exposed edges or corners, including the use of dummy chamfers and false joints to provide a neat and uniform appearance, unless otherwise indicated on the Drawings or directed by the Engineer. Chamfer is not required where specific details show sealant grooves at joints.

F. The Contractor will construct all forms straight, true, plumb, and square within a tolerance horizontally of one (1) in 200 and a tolerance vertically of one (1) in 500.

G. Forms for exposed surfaces shall be coated with a form release agent, approved by the

Engineer, which shall be applied shortly before the concrete is placed. The release agent shall leave concrete surface unstained, ready for paint, plaster or other similar coatings or treatments. After applying, surplus release agent on the form surfaces and any release agent on the reinforcing steel or other surfaces requiring bond with the concrete shall be removed. Forms for unexposed surfaces may be thoroughly wetted in lieu of release agent, immediately before the placing of concrete, except that in freezing weather release agent shall be used. Acceptable release agents are Euclid Chemical Co. “EUCOSLIP”;

W.R. Meadows, Sealtight “Duogard” or approved equal.

H. Plywood form panels will be nailed directly to studs and applied in a manner to minimize the number of joints. The Contractor will make all panel joints tight butt joints with all edges true and square.

I. Temporary openings shall be provided at the base of wall forms and at other points where necessary to facilitate cleaning and inspection immediately before depositing concrete.

3.02 REMOVAL OF FORMS

A. No forms or form support shall be removed from the formed surface for at least twenty-four

(24) hours and until approved by the Engineer. Forms shall be removed in such a manner as to ensure the complete safety of the structure. Responsibility for the removal of forms shall be with the Contractor. However, the following minimum requirements shall be adhered to:

1. In cold or inclement weather, the requirement for removal of forms shall be as stated in ACI 306.

2. Forms for supporting reinforced concrete roofs or floors shall not be removed nor form-supports slackened for a period of twenty-eight (28) days unless the Contractor can produce satisfactory evidence that the concrete has attained the specified 28-day strength characteristic.

West Branch Regional Authority 03100-4 January 2026

3. Portions of the structure which will be subject to construction loads or backfill shall have attained sufficient strength to withstand these loads and the Contractor may be required to produce evidence that such strength has been attained.

4. No construction loads exceeding the structural design loads shall be supported upon any unshored portion of the structure under construction.

B. Evidence that the concrete has attained a strength sufficient for the above conditions shall consist of reports of compression tests made on job-cured cylinders. The cost of such tests shall be borne by the Contractor.

C. In case the Contractor shall remove any form or slacken any supports before the above conditions have been met, the Engineer may require removal of the concrete elements, even though there may be no apparent defect.

D. The Contractor will cut nails and tie wires or form ties off flush and leave all surfaces smooth and clean. The Contractor will remove metal spreader ties on exposed concrete by removing or snapping off inside the wall surface and pointing up and rubbing the resulting pockets to match the surrounding areas.

E. The Contractor will flush all holes resulting from the use of spreader rods and sleeve nuts, using water, and then solidly pack throughout the wall thickness with cement grout applied under pressure by means of a grouting gun immediately after removing forms. Grout will be one (1) part Portland cement to 2-1/2 parts sand.

3.03 REUSE OF FORMS

A. Reuse of forms will be subject to advance approval of the Engineer. Lumber once used in forms will have nails withdrawn and surfaces to be in contact with concrete will be thoroughly cleaned before being used again. Except as specifically approved in advance by the Engineer, reuse of forms will in no way delay or change the schedule for placement of concrete from the schedule obtainable if all forms were new and will in no way impart less structural stability to the forms nor less acceptable appearance to finished concrete.

Reuse of forms will not be permitted for forming surfaces requiring a rubbed finish.