CONCRETE CURBS, GUTTERS AND SIDEWALKS

PART 1 - GENERAL A. Description

This section describes materials and construction of concrete curbs, gutters, and sidewalks.

For projects located in the public right-of-way, the respective jurisdictional agency (City of Costa Mesa, the City of Newport Beach, or the County of Orange) permit requirements and specifications shall take precedence over the requirements specified herein.

B. Related Work Specified Elsewhere

1. Trenching, Backfilling, and Compacting: 02223.

2. Concrete Formwork: 03100.

3. Concrete Reinforcement: 03201.

4. Concrete: 03300.

PART 2 - MATERIALS A. Forms

1. General: Forms shall be as required in Section 03100 (Concrete Formwork). Stakes and braces shall be provided to hold forms securely in place.

2. Sidewalk Forms: Sidewalk forms shall be 2-inch dressed lumber, straight and free from defects, or standard metal forms. Where short-radius forms are required, 1-inch dressed lumber of plywood may be used.

B. Aggregate Base Course

Crushed rock base shall be clean 3/4-inch and smaller crushed rock or crushed gravel, free from foreign material, and conforming to Crushed Aggregate Base as specified by Standard Specifications of Public Works Construction Section 400-2. An acceptable alternative to Crushed Aggregate Base is Crushed Miscellaneous Base as specified by Standard Specifications Section 200-2.4.

C. Expansion Joint Filler

Premolded expansion joint filler shall be 1/4-inch thick for curbs and 1/4-inch thick for sidewalks, or as required or allowed by the permitting agency.

D. Concrete

Conform to Section 03300 (Concrete).

E. Reinforcing Steel

Conform to Section 03201 (Concrete Reinforcement).

F. Excavation and Backfill

Conform to Section 02223 (Trenching, Backfilling, and Compacting).

PART 3 - EXECUTION

A. Preparation of Subgrade

Subgrade shall be excavated and shaped to line, grade, and cross section. The top 12-inches of subgrade shall be compacted to 90% relative compaction. All soft material disclosed by excavating shall be removed and replaced with aggregate base as directed. The finished subgrade shall be within a tolerance of +/-0.02 of a foot of the grade and cross section shown and shall be smooth and free from irregularities at the specified relative compaction. The subgrade shall extend over the full width of construction. The Mesa Water Representative's approval of finished subgrades must be received prior to continuance of the work.

B. Placing Aggregate Base

After the subgrade for curbs, sidewalks, and roadway slabs is compacted and accepted, the contractor shall place and spread aggregate base material, sprinkle with water, and compact to 90% relative density. The surface of the compacted base shall be at the proper level to receive concrete. Curbs and sidewalks shall be underlain by 4-inches or more of compacted aggregate base material.

C. Setting Forms

Forms shall conform to Section 03100 (Concrete Formwork). Forms for a face-of-curb shall not have any horizontal joints within 7-inches of the top of the curb. Forms shall be braced to prevent change of shape or movement in any direction resulting from the weight of the concrete. Short-radius curved forms shall be constructed to exact radius. Tops of forms shall not depart from gradeline more than 1/8-inch when checked with a 10-foot straightedge.

Alignment of straight sections shall not vary more than 1/8-inch in 10-feet.

D. Curb Construction

1. Jurisdictional Requirements: Curbs shall be reconstructed to original line and grade if removed. Curbs shall conform to the requirements of the respective jurisdictional agency.

CONCRETE CURBS, GUTTERS AND SIDEWALKS 02528 - 2

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change in thickness of section, at the end of curbs at buildings and other structures, and at connections to existing curbs.

3. Notification: The Mesa Water's Representative shall be notified one day in advance of planned concrete placement.

4. Concrete Finish: When the concrete has set sufficiently to support its own weight, the front form shall be removed and exposed surfaces finished. The formed face shall be finished by rubbing with a burlap sack or similar device to produce a uniformly textured surface, free of form marks, honeycomb, and other defects. Defective concrete shall be removed and replaced at no expense to Mesa Water where Mesa Water is a party of the contract. Upon completion of the finishing, curing compound shall be applied to exposed surfaces of the curb. Curing shall continue for a minimum of five days.

5. Backfill: Seven days (minimum) after pouring the concrete, the curb shall be backfilled with earth free from rocks, 2-inches and larger, and other foreign material.

Backfill shall be tamped firmly in place.

6. Alignment and Grade: Finished curb shall have a uniform grade and alignment. Any section of curb showing abrupt changes in alignment or grade, or which is more than 1/4-inch away from its intended location, as staked, shall be removed and reconstructed at no additional cost to Mesa Water where Mesa Water is a party to the contract.

7. Protection of Work: All concrete surfaces and/or structures shall be protected until the project containing the work is accepted.

E. Sidewalk Construction

1. General Requirements: Unless shown otherwise, sidewalks shall be placed in a single pour, 4-inches thick. Walks shall slope 1/4-inch per foot upward from the top of curb. Concrete shall be placed, processed, finished, and cured in conformance with the applicable requirements of ACI 614.

2. For sidewalks within a City public right-of-way, sidewalk construction shall be in accordance with the jurisdictional agency’s requirements.

3. New Sidewalk: Where new sidewalk is to abut existing concrete, the existing concrete shall be sawcut to a depth of 2-inches and the concrete chipped out to sound material and a plane surface.

4. Expansion Joints: Preformed expansion joints shall be placed at 20-foot intervals or less to match those in the adjacent curb, where the sidewalk ends at a curb, and around posts, poles, or other facilities located within the sidewalk. Expansion joints shall be placed between sidewalks and buildings or other structures.

locations opposite the contraction joints in the curb and at 10-foot intervals along the sidewalk. These joints shall be 3/16-inch by 1-inch weakened plane joints. They shall be straight and at right angles to the top of the walk.

6. Notification: The Mesa Water's Representative shall be notified one day in advance of planned concrete placement.

7. Concrete Finish: The top surface of the sidewalk shall receive a broom finish with a fine-hair broom in line with the length of the walk. All edges, joints, and markings shall be tooled. The walk shall be scored transversely at 5-foot intervals with a jointing tool. Upon completion of the finishing, an approved curing compound shall be applied to exposed surfaces. Sidewalks shall be protected from damage until final acceptance.

END OF SECTION

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