Section 2511. Removal and Construction of Sidewalks and Recreational Trails.

2511.01 DESCRIPTION.
This work shall consist of removal of sidewalks and recreational trails or portions of them and/or the construction of new sidewalks and recreational trails according to the contract documents.

2511.02 MATERIALS.

A. Portland Cement Concrete.
The Portland cement concrete used for sidewalks and recreational trails shall be Class B concrete produced and placed in accordance with Section 2301. For sidewalk and recreational trail construction included in PCC paving projects, the Contractor may use the approved paving mixture for the project. A Class 2 durability or better aggregate, in accordance with Article 4115.04, will be required.

When construction of a sidewalk or recreational trail is associated with a bridge project the Contractor may use the concrete approved for the bridge structure with Class C as the minimum.

B. Hot Mix Asphalt.
The HMA used for sidewalks and recreational trails not adjacent to pavement shall be 100,000 ESAL, 3/8 inch (9.5 mm) in accordance with Section 2303.When the recreational trail or sidewalk is adjacent to the pavement and also functions as the pavement shoulder, 1,000,000 ESAL, 1/2 inch (12.5 mm) base mixture shall be used. The Performance Grade binder shall be PG 58-28 or PG 52-34 as specified in the plans.

C. Subbase and Granular Surface.
The subbase and granular surface shall be as specified in the contract documents.

D. Detectable Warnings.
Detectable warnings shall be in accordance with Materials I.M. 411.

2511.03 CONSTRUCTION.

A. Removal of Sidewalks and Recreational Trails.
The Contractor shall remove the sidewalks and recreational trails as shown in the contract documents. If only portions of the sidewalks or recreational trails are to be removed, the boundaries of removal shall be made by a vertical saw cut not less than 1 inch (25 mm) deep before breaking the removal. Any areas of the sidewalk or recreational trail not designated for removal but which are removed, broken, or damaged by the Contractor’s operations shall be removed and replaced by the Contractor with no additional cost to the Contracting Authority. Removal of sidewalks and recreational trails shall be in accordance with Article 2510.02.

B. Preparation of Subgrade.

1. Sidewalks.
The subgrade for sidewalks shall be prepared by excavating or filling with suitable earth to a depth below the finished grade line so that, when tamped or rolled until smooth, firm, and hard, the subgrade will be uniform and at the required depth below the finished grade line.

2. Recreational Trails.
When the recreational trail is to be constructed on natural subgrade special compaction of subgrade for the recreational trail will be required. The Contractor shall disk, scarify, mix, and recompact the top 12 inches (300 mm) of subgrade with moisture and density control. Compact to not less than 95% maximum density as determined by Iowa DOT Materials Laboratory Test Method 103; moisture content not less than optimum or more than 4% above optimum moisture content.

When the recreational trail surface is to be constructed on an existing granular surface, the subbase (existing granular surface) shall be prepared in accordance with the contract documents.

C. Portland Cement Concrete.

1. Placing.

a. Hand Finished Sidewalks and Recreational Trails.
Forms of wood or steel shall be in accordance with Article 2301.07, A, 1, b.

The subgrade shall be thoroughly moistened. Concrete shall be deposited for the full depth of slab in one operation. It shall be consolidated by tamping or vibration, and the excess concrete screeded off flush with the forms. Edges adjacent to all forms, expansion joints, curbs, or fixtures in the surface shall be thoroughly consolidated.

b. Slip Form Sidewalks and Recreational Trails.
Self propelled slip form pavers shall meet the requirements of Section 2301. Other slip form paving machine shall be approved by the Engineer and designed for the specific purpose of placing, consolidating, and finishing concrete sidewalk and recreational trail slabs without use of fixed side forms.

2. Curb Ramps.
Construction of curb ramps shall require detectable warnings.

All detectable warnings shall be installed according to the manufacturer's recommendations. The detectable warnings shall contrast visibly with the adjoining surfaces, either light-on-dark or dark-on-light. Refer to Americans with Disabilities Act Accessibility Guidelines (ADAAG) for contrast requirements at http://www.access-board.gov/adaag/html/adaag.htm#4.29.2.

If crossings are marked; the ramp, exclusive of flares, shall be located entirely within the crosswalk markings.

3. Finishing.
After consolidation, the concrete surface shall be finished to a uniform, slip resistant, wet burlap drag or broom finish texture true to the line and grade specified in the contract documents. The broom finish shall be obtained by dragging a suitable broom transversely across the surface of the plastic concrete.

a. Sidewalks.
After the surface has been floated, the edges of the slabs shall be finished with a suitable edging tool. Unless otherwise shown, the finished surface shall have a cross slope of 1/4 inch per foot (20 mm/m) for drainage.

For PCC sidewalks the transverse joint spacing shall be equal to the pavement width. The concrete shall be cut through for not less than 25% of the depth with a pointed trowel or suitable spading tool, and the concrete edged on both sides. In lieu of using a pointed trowel or suitable spading tool, the Contractor may cut these lines within 12 hours after placement of concrete with a 1/8 inch (3 mm) blade saw that is approved by the Engineer. Metal dividers will be considered for approval, in lieu of cutting.

b. Recreational Trails.
For PCC recreational trails the transverse joints spacing shall be equal to the pavement width. All transverse joints shall be saw cut not tooled. The transverse joints shall be cut 1/8 inch (3 mm) wide and not less than 1 inch (25 mm) in depth. No sealant will be required.

Recreational trails 12 feet (2.6 m) wide or less, shall not have a longitudinal joint.

4. Protection and Curing.
After finishing, the concrete shall be cured and protected by one of the methods described in Article 2301.19.

5. Isolation Joints.
Isolation joints shall be constructed at all points where sidewalks or recreational trails meet other walks, curbs, or fixtures in the surface. These joints shall be constructed by installing a 1/2 inch (13 mm), full depth strip of approved premolded joint material.

6. Time for Opening Pavement for Use.
PCC sidewalks and recreational trails shall be opened a minimum of seven calendar days after placement or when flexural strength reaches 400 psi (2.75 MPa) as determined by Materials I.M. 383.

D. Hot Mix Asphalt.
HMA sidewalks and recreational trails shall be constructed in accordance with Article 2303.03 and 2303.04. Compaction shall be Class 1C.

E. Smoothness.
Sidewalk and recreational trail smoothness shall be in accordance with Article 2301.16, D, except for the requirements for pavement and bridge approach sections for Primary projects.

Areas may be checked by the Engineer with a surface checker and shall not exceed 1/4 inch in 10 feet (6 mm in 3 m). For each bump exceeding these requirements, the Contractor will be assessed $50 or the bump corrected as agreed upon by the Engineer and Contractor.

F. Weight Limits.
Construction equipment on both PCC and HMA sidewalks and recreational trails shall be limited to 5 ton (5 Mg).

G. Pavement Markings.
Pavement markings shall be placed in accordance with Section 2527.