atch 1 2510 Concrete Sidewalks.pdf

Concrete sidewalks/Driveways/Curb and Gutter FA5000-12-R-0001 Attachment 1

2510- 1

1. APPLICABLE PUBLICATIONS:

The publications listed below form a part of this specification to the extent referenced. The publications are referred to in the text by the basic designation only.

1.1 American Association of State Highway and Transportation Officials M 182 Burlap Cloth Made From Jute or Kenaf.

(AASHTO) Publication:

1.2 American Society for Testing and Materials (ASTM) Publications

: C 94 Ready-Mixed Concrete.

C 171 Sheet Materials for Curing Concrete. C 173 Air Content of Freshly Mixed Concrete by the Volumetric Method. C 231 Air Content of Freshly Mixed Concrete by the Pressure Method. C 309 Liquid Membrane-Forming Compounds for Curing Concrete. D 1751 Performed Expansion Joint Fillers for Concrete Paving and Structural Construction (Non-extruding and Resilient Bituminous Types). D 1752 Performed Sponge Rubber and Cord Expansion Joint Fillers for Concrete Paving and Structural Construction. D 1850 Concrete Joint: Sealer, Cold- Application Type.

2. FIELD CONTROL TESTS:

2.1 Preparation of field-control samples and testing of samples shall be by the Contractor at no additional cost to the Government. The taking of samples, the making of test specimen, and the testing thereof shall be performed under the supervision of the Project engineer / project inspector.

3. MATERIALS:

3.1 Concrete Curing Materials:

3.1.1 Burlap: AASHTO M 182 having a weight of 14 ounces for more per square yard when dry.

3.1.2 Impervious Sheeting: ASTM C 171.

3.1.3 Liquid Membrane Curing Compound: ASTM C 309, Type 1D Compound shall be free of paraffin or petroleum.

3.2 Concrete Protection Materials: Linseed oil mixture shall be equal parts, by volume, of linseed oil and either mineral spirits, naphtha, or turpentine. At the option of the Contractor, prepared linseed oil mixture formulated specifically for application to concrete to provide protection against the action of deicing chemicals may be used except that emulsified mixtures are not acceptable.

3.3 Joint Materials:

Pavements - IDIQ

FXSB 11-2102

Section 2510

Concrete Sidewalks / Driveways / Curb and Gutter

2510- 2

3.3.1 Expansion Joint Fillers: ASTM D 1751 or ASTM D 1752 or shall be resin impregnated fiberboard conforming to the physical requirements of ASTM D 1752.

3.3.2 Joint Sealers: ASTM D 1850.

4. CONCRETE PROPERTIES:

4.1 Concrete and materials therefore shall conform to the applicable requirements of ASTM C 94, except as specified below.

4.2 Slump for concrete sidewalks, driveways, blast deflector foundations: Maximum 4.25 inches.

Slump for concrete curb and gutters: Maximum 3.0 inches

4.3 The concrete mixtures shall have air content by volume of concrete of 5 to 7 percent

, based on measurements made immediately after discharge from the mixer. Air content shall be determined in accordance with ASTM C 173 or ASTM C 231. ASTM C 231 shall be used with concretes and mortars made with relatively dense natural aggregates.

4.4 Minimum compressive strength shall be 4000 PSI @ 28 days

for sidewalks, driveways, curbs and gutters, handicap ramps, loading docks, blast deflector foundations, and barrier walls.

5. FORMS:

5.1 Sidewalks, driveways, docks, ramps, foundations

: The forms shall be of wood or steel, straight of sufficient strength to resist springing during depositing and consolidating concrete, and of a height equal to the full depth of the finished concrete.

5.1.1 Wood forms shall be surfaced plank, 2-inch nominal thickness straight and free from warp, twist, loose knots, splits or other defects. Wood forms shall have a nominal length of 10 feet, with a minimum of three stakes per form, at maximum spacing of 4 feet. Corners, deep sections, and radius bends shall have additional stakes and braces, as required. Radius bends may be formed with 3/4-inch boards, laminated to the required thickness.

5.1.2 Steel forms shall be channel-formed sections with a flat top surface and with welded braces at each end and at not less than two intermediate points. Form ends shall be interlocked and self-aligning. Forms shall include flexible forms for radius forming, corner forms, form spreaders, and fillers. Forms shall have a nominal length of 10 feet, with a minimum of two welded stake pockets per form. Stake pins shall be solid steel rods with chamfered heads and pointed tips, designed for use with steel forms.

5.2 Curb and Gutter

: Curb and gutter forms shall be of wood or steel, straight, and or sufficient strength to resist springing during depositing and consolidating the concrete. The outside forms shall have a height equal to the full depth of the curb or gutter. The inside form of curb shall have batter as indicated and shall be securely fastened to and supported by the outside form. Straight forms of wood shall be surfaced plank, 2-inch nominal thickness, straight and free from warp, twist, loose knots, splits, or other defects.

5.2.1 Wood forms shall have a nominal length of 10 feet, with a minimum of three stakes per form, at maximum spacing of 4 feet. Corners, deep sections, and radius bends shall have additional stakes and braces, as required. Radius bends may be formed with 3/4-inch boards, laminated to the

2510- 3 required thickness.

5.2.2 Steel forms shall be channel-formed sections with a flat top surface and with welded braces at each end and at not less than two intermediate points. From ends shall be interlocked and self-aligning. Forms shall include flexible forms for radius forming, corner forms, form spreaders, and fillers. Forms shall have a nominal length of 10 feet, with minimum of two welded stake pockets per form. Stake pins shall be solid steel rods with chamfered heads and pointed tips, designed for use with steel forms. Rigid forms shall be provided for curb or curb returns with a radius of 10 feet or more, where grade changes occur in the return, or where the central angle is such that a rigid form with a central angle of 90 degrees cannot be used. Back forms for curb returns may be made of 1- 1/2-inch benders, for the full height of the curb, cleated together.

6. SUB-BASE PREPARATION:

6.1 The sub-base shall be constructed to the required grade and cross section. Any additional material required to bring the sub-base under sidewalks, curbs, and curbs and gutters, driveways, loading docks, or handicap ramps to proper elevations shall be classified material or sub-base and shall be a separate bid item.

6.2 Sidewalks, driveways, docks, ramps, foundations: The sub-base shall be thoroughly wetted and then compacted. Yielding material deflecting more than 1/2 inch shall be removed to a depth of not less than 4 inches below sub-base elevation and replaced with an approved classified material or sub-base. The material shall then be compacted to 96 percent density. The completed sub-base shall be tested for grade and cross section with a template extending the full width of the sidewalk and supported between side forms.

6.3 Curb and Gutter Sub-base

: The sub-base shall be of materials equal in bearing quality to the sub-base under the adjacent pavement and shall be placed and compacted to conform with applicable requirements of SECTION 2225 SUB-BASE AND CLASSIFIED BACKFILL. The sub-base shall be tested for grade and cross section by means of a template extending the full width of the curb and gutter.

6.4 Maintenance of Sub-base: The sub-base shall be maintained in a smooth, compacted condition, in conformity with the required section and established grade until the concrete is placed. The sub-base shall be in a moist condition when concrete is placed. The sub-base shall be prepared and protected so as to produce a sub-base free from frost when the concrete is deposited.

7. FORM SETTING:

7.1 Sidewalks, driveways, docks, ramps, foundations

: Forms shall be set with the upper edge true to line and grade and shall be held rigidly in place by stakes places at intervals not to exceed 4 feet.

After forms are set, grade and alignment shall be checked with a 10-foot straightedge. Forms shall conform to line and grade with an allowable tolerance of 1/8 inch in any 10-foot long section. Forms shall have a transverse slope of 1/4 inch per foot with the low side adjacent to the roadway. Forms shall be coated with form oil each time before concrete is placed. Wood forms may, instead, be thoroughly wetted with water before concrete is placed, except that with probable freezing temperatures, oiling is mandatory. Side forms shall not be removed for less than 12 hours after finishing has been completed.

7.2 Curbs: Forms for curbs shall be carefully set to alignment and grade and to conform to the

2510- 4 dimensions of the curb. Forms shall be held rigidly in place by the use of stakes placed at intervals not to exceed 4 feet. Clamps, spreaders, and braces shall be used where required to insure rigidity in the forms. The forms on the front of the curb shall be removed not less than 2 hours nor more than 6 hours after the concrete has been placed. Forms back of curb shall remain in place until the face and top of the curb have been finished as specified for concrete finishing. Gutter forms shall not be removed while the concrete is sufficiently plastic to slump in any direction. Forms shall be cleaned and coated with form oil each time before concrete is placed. Wood forms may, instead, be thoroughly wetted with water before concrete is placed, except that with probable freezing temperatures, oiling is mandatory.

8. CONCRETE PLACEMENT AND FINISHING:

8.1 Sidewalks, driveways, docks, ramps, foundations

: Concrete shall be placed in the forms in one layer of such thickness that when compacted and finished will be of the thickness indicated. After concrete has been placed in the forms, a strike-off guided by side forms shall be used to bring the surface to proper section to be compacted. The concrete shall be tamped and consolidated with a suitable wood or metal tamping bar, and the surface shall be finished to grade with a wood float.

Finished surface of the walk shall not vary more than 3/16 inch from the testing edge of a 10 foot-straightedge. Irregularities exceeding the above shall be satisfactorily corrected. The surface shall be divided into rectangular areas by means of contraction joints spaced at not more than 5 feet on centers.

8.1.1 Concrete Finishing: After straight edging, when most of the water sheen has disappeared, and just before the concrete hardens, the surface shall be finished to a smooth and uniformly fine granular or sandy texture free of waves, irregularities, or tool marks. A scored surface shall be produced by brooming with a fiber-bristly brush in a direction transverse to that of the traffic.

8.1.1.1 Exposed Aggregate Finish: When indicated on the delivery order, provide an exposed aggregate finish that meets the Municipality of Anchorage Standards. For payment, “Exposed Aggregate Finish” concrete sidewalks will be counted as 1.50 square yards (SY) of “New Concrete Sidewalks (Continuous)” for each 1.0 square yards (SY) of “Exposed Aggregate Finish” concrete sidewalks measured in place. The adjustment for “New Concrete Sidewalks / Less than 2,000 SY” is not used for “Exposed Aggregate Finish” concrete sidewalks.

8.1.2 Edge and Joint Finishing: All slab edges, including those at formed joints, shall be finished carefully with an edger having a radius of 1/8 inch. Transverse joints shall be edged before brooming, and the brooming shall eliminate the flat surface left by the surface face of the edger.

Corner and edges which have crumbled and areas which lack sufficient mortar for proper finishing shall be cleaned and filled solidly with a properly proportioned mortar mixture and then finished.

8.1.3 Contraction Joints: The contraction joints shall be formed in the fresh concrete by cutting a groove in the top portion of the slab to a depth of at least one-fourth of the concrete slab thickness, or by sawing a groove in the hardened concrete with a power-driven saw, unless otherwise approved. Sawed joints shall be constructed by sawing a groove in the concrete with a 1/8-inch blade to the depth indicated. The time of sawing shall be varied, depending on existing and anticipated weather conditions, and such sawing shall be at the required rate.

8.1.4 Expansion Joints: Transverse expansion joints shall be installed at sidewalk/driveway returns and opposite expansion joints in adjoining curbs. Where the sidewalk/driveway is not in contact with the curb, transverse expansion joints shall be installed 30 feet on centers. Transverse

2510- 5 expansion joints shall be filled with 1/2 inch joint filler strips. Joint filler shall be placed with top edge 1/4 inch below the surface and shall be held in place with steel pins of other devices to prevent warping of the filler during floating and finishing. Immediately after finishing operations are completed, joint edges shall be rounded with an edging tool having a radius of 1/8 inch, and concrete over the joint filler shall be removed. Expansion joints shall be formed about structures and features that project through or into the sidewalk pavement, using joint filler of the type, thickness, and width indicated. The filler shall be installed in such manner as to form a complete, uniform separation between the structure and sidewalk pavement. At the end of the curing period, expansion joints shall be carefully cleaned and filled with joint sealer. Concrete at the joint shall be above 50 degrees and the atmospheric and pavement temperatures shall be above 50 degrees F at the time of application of joint-sealing materials. Joints shall be filled flush with the concrete surface in such manner as to minimize spilling on the walk surface. Spilled sealing material shall be removed immediately and the surface of the walk cleaned. Dummy groove joints shall not be sealed.

8.1.5 Surface Uniformity: The completed surface shall be uniform in color and free of surface blemishes and tool marks.

8.2 Curb and Gutter Concrete

: Concrete shall be placed in layers not to exceed 12 inches. Concrete shall be thoroughly consolidated by tamping and spading or with approved mechanical vibrators.

8.2.1 Concrete Finishing: The edges of the gutter and top of the curb shall be rounded with an edging tool to a radius of 1/2 inch and the surfaces shall be floated and finished with a smooth wood float until true to grade and section and uniform in texture. Floated surfaces shall then be brushed with a fine-hair brush with longitudinal strokes. Immediately after removing the front curb form, the face of the curb shall be rubbed with a wood or concrete rubbing block and water until blemishes, form marks, and tool marks have been removed. The surface, while still wet, shall be brushed in the same manner as the gutter and curb top. The top surface of gutter and entrance shall be finished to grade with a wood float. Except at grade changes or curves, finished surfaces shall not vary, from the testing edge of 10-foot straightedge, more than 1/8 inch for gutter and entrance and 1/4 inch for top and face of curb. Irregularities exceeding the above shall be satisfactorily corrected. Visible surfaces and edges of finished curb and gutter shall be free of blemishes and form and tool marks, and shall be uniform in color, shape, and appearance.

8.2.2.1 Contraction Joints: Contraction joints shall be constructed by means of 1/8-inch thick separators, of a section conforming to the cross section of the curb and gutter. Contraction joints shall be constructed directly opposite contraction joints in abutting portland-cement-concrete pavement. Where curb and gutter do not abutt portland-cement-concrete pavements, contraction joints shall be so placed that monolithic sections between curb returns will not be less than 5 feet nor greater than 15 feet in length. Separators shall be removed as soon as practicable after concrete has set sufficiently to preserve the width and shape of the joint. Separators shall be removed prior to finishing.

8.2.2.2 Expansion Joints: Expansion joints shall be formed by means of performed expansion-joint filler material cut and shaped to the cross section of curb and gutter. Expansion joints shall be provided in curb and at the end of all returns. Expansion joints shall be provided in curb and gutter directly opposite expansion joints of abutting portland-cement-concrete pavement and shall be of the same type and thickness as joints in the pavement. Where curb and gutter do not abutt portland-cement-concrete pavement, expansion joints at lease 1/2-inch in width shall be provided at intervals not exceeding 30 feet.

2510- 6

8.3 Curb-Forming Machines

: Curb-forming machines for constructing curb and gutter will be accepted by the project engineer / project inspector based on trial use on the job. Use of the equipment shall be discontinued at any time during construction if the equipment produces unsatisfactory results, and the work shall be accomplished as specified above. Unsatisfactory work shall be removed and reconstructed for the full length between regularly scheduled joints. Removed portions shall be disposed of as directed. Curb-forming machines shall not be used in areas where the existing sidewalk butts up against the existing curb and gutter to be removed.

9. CURING AND PROTECTION:

9.1 Curing

: Immediately after the finishing operations, exposed concrete surfaces shall be cured by one of the following methods as the contractor may elect.

9.1.1 Mat Method: The entire exposed surface shall be covered with two or more layers of burlap.

Mats shall overlap each other at least 6 inches. The mat shall be thoroughly wetted with water prior to placing on concrete surface and shall be kept continuously in a saturated condition and in intimate contact with concrete for not less than 7 days.

9.1.2 Impervious Sheeting Method: The entire exposed surface shall be wetted with a fine spray of water and then covered with impervious sheeting material. Sheets shall be laid directly on the concrete surface with the light-colored side up and overlapped 12 inches when a continuous sheet is not used. The curing medium shall not be less than 18 inches wider than the concrete surface to be cured, and shall be securely weighted down by heavy wood planks, or by placing a bank of moist earth along edges and laps in the sheets. Sheets shall be satisfactorily repaired or replaced of torn or otherwise damaged during curing. The curing medium shall remain on the concrete surface to be cured for not less than 7 days.

9.1.3 Membrane-Curing Method: The entire exposed surface shall be covered with a membrane-forming curing compound. Curing compound shall be applied to two coats by hand-operated pressure sprayers at a coverage of approximately 200 square feet per gallon for both coats. The second coat shall be applied in a direction approximately at right angles to the direction of application of the first coat. The compound shall form a uniform, continuous, coherent film that will not check, crack, or peel and shall be free from pinholes or other imperfections. Apply an additional coat to all surfaces showing discontinuity, pinholes or other defects.

9.1.3.1 Concrete surfaces that are subjected to heavy rainfall within 3 hours after curing compound has been applied shall be re-sprayed by the above method and at the above coverage at no additional cost to the Government. Expansion joint openings shall be sealed at the top by inserting moistened paper or fiber rope or covering with strips of waterproof paper prior to application of the curing compound, in a manner to prevent the curing compound entering the joint.

9.1.3.2 Concrete surfaces to which membrane curing compounds have been applied shall be adequately protected for 7 days from pedestrian and vehicular traffic and from any other action that might disrupt the continuity of the membrane. Any area covered with curing compound and damaged by subsequent construction operations within the 7-day curing period shall be re-sprayed as specified above at no additional expense to the government.

9.2 Backfilling: After the 7 day curing of the concrete, all debris larger than 6” including asphalt chunks, concrete chunks and larger rocks shall be removed from the work area behind the new curbs and disposed of off the site. The areas disturbed by the contractor adjoining the concrete

2510- 7 curbs/gutters and sidewalks shall be backfilled, graded, and compacted to conform to the surrounding area in accordance with existing lines and grades and in some cases, in accordance with new lines and grades. After completion of grading, the disturbed areas shall be top soiled and hydro-seeded, which are separate pay items. Additional classified backfill required is a separate pay item.

9.3 Protection: Completed concrete shall be protected from damage until accepted. The Contractor shall repair damaged concrete and clean concrete discolored during construction. Concrete that is damaged shall be removed and reconstructed for the entire length between regularly scheduled joints. Refinishing the damaged portion will not be acceptable. Removed damaged portions shall be disposed of as directed.

9.3.1 Protective Coating: Protective coating of linseed oil mixture shall be applied to exposed-toview concrete surfaces.

9.3.1.1 Application: Backfilling and curing operation shall be completed prior to applying protective coating. Concrete shall be surface dry and thoroughly clean before each coating.

Concrete shall be surface dry and thoroughly clean before each application. Coverage shall be not more than 50 square yards per gallon for first application, except that the number of applications and coverage for each application for commercially prepared mixture shall be in accordance with the manufacturer's instructions. Coated surfaces shall be protected from vehicular and pedestrian traffic until dry.

9.3.1.2 Precautions: Protective coating shall not be heated, and shall be protected from open flame, sparks, and fire adjacent to open containers or applicators. Material shall not be applied at temperatures lower than 50 F.

9.4 Cold Weather Requirements

: Perform IAW ACI 306 "Cold Weather Concreting" when concrete is placed where the air temperature is below +40 degrees F. Submit cold weather plan for approval.

10. SEALING JOINTS:

10.1 The approximately horizontal sections of expansion joints and the top 1-inch depth of contraction-joint openings of gutter shall be sealed with joint sealer. The joint opening shall be thoroughly cleaned before the sealing material is placed. Sealing shall be done so that the material will not be spilled on exposed surfaces of the concrete. Concrete at the joint shall be surface dry and atmospheric and concrete temperatures shall be above 50 degrees F at the time of application of joint-sealing materials. Excess material on exposed surfaces of the concrete shall be removed immediately and exposed concrete surfaces cleaned.

11. SUBMITTALS:

11.1 The Concrete mix design showing the entrained air content, cement content, maximum water content, slump range, cement type and the estimated strength shall be submitted for approval. The curb and gutter details to be constructed shall be submitted for approval. The concrete curing material and joint materials shall be submitted for approval.

12. CONTRACTOR’S QUALITY CONTROL:

2510- 8

12.1 Verify dimensions of new sidewalks, driveways, curbs and gutters, etc.

12.2 Assure that testing occurs to meet the specs.

12.3 Assure that concrete mix design is being maintained as specified.

13. TESTING REQUIREMENTS:

13.1 Air Content

: At least one test for air content shall be made on each 40 CY of concrete placed.

Provide at least one air content minimum per day for pours less than 40 CYS.

13.2 Slump

: At least one test for slump shall be made on each 20 CY of concrete placed. Provide at least one slump minimum per day for pours less than 20 CYS.

13.3 Compressive Cylinder Tests

: At least one set of 3 compression tests shall be made on each 100 CY of concrete placed. Provide at least one set minimum per day for pours less than 100 CY.

Provide 2 test results at 28 days per set.

14. UNIT OF MEASUREMENT AND PAYMENT: Per the Bid Schedule and Section 1020.

End of Section