2512.01 DESCRIPTION.
This work shall consist of the construction of a PCC curb or curb and gutter, separate from the construction of a pavement in accordance with the contract documents. When construction of curb or curb and gutter is associated with a bridge structure the concrete used shall be produced, transported, and placed in accordance with Section 2403.

2512.02 MATERIALS.
The respective materials shall meet requirements of Division 41.

2512.03 CONCRETE AND PROPORTIONS.
The concrete used in curb or curb and gutter not associated with a bridge structure shall be Class C concrete produced and placed in accordance with Section 2301. When construction of curb or curb and gutter is associated with a bridge structure the concrete used shall be Class D. The consistency of the concrete as measured by the slump test shall not exceed 3 inches (75 mm).

2512.04 CONSTRUCTION.
Construction of PCC curb or curb and gutter shall meet the following requirements:

A. Preparation of the Subgrade.
The subgrade upon which concrete curb or curb and gutter is to be placed shall be prepared by excavating or filling with suitable earth to a depth below finished grade line so that, when tamped or rolled until smooth and firm, the subgrade will be uniform and at the desired depth below finished grade line.

When curb or curb and gutter is constructed on a filled section, the compacted fill shall extend a minimum of 1 foot (0.3 m) outside the form line and shall not be lower than the base of the form at the form line. When concrete is placed upon it, the subgrade shall be thoroughly moistened or shall be covered with a layer of plastic film meeting requirements of Section 4107.

B. Intentionally Left Blank.

C. Slip Form Equipment.
Slip form equipment may be used.

D. Forms.
Unless slip form equipment is permitted, all straight sections of curb and gutter shall be formed with steel forms for the full depth of the concrete. Wood forms may be used on curving sections.

Any extensions used to obtain the required depth of form shall be faced with steel and shall be rigidly welded or bolted to the main form.

The top face of forms shall not vary from a true plane by more than 1/8 inch in 10 feet (3 mm in 3 m), and the upstanding face, including any extension, shall not vary from a true plane by more than 1/4 inch in 10 feet (6 mm in 3 m). Forms that are bent, twisted, warped, broken, or battered shall be removed from the work. Repaired forms shall not be used until they have been inspected and approved by the Engineer. Flexible or rigid forms of proper curvature shall be used for curves having a radius of 100 feet (30 m) or less.

While concrete is being placed and consolidated, the front face of the curb shall be formed with fixed or movable forms. Movable slip forms shall be at least 6 feet (1.8 m) in length and shall have a suitable opening for placing and consolidating concrete. Slip forms shall be subject to the approval of the Engineer.

Forms shall be set with the upper edge to correct line and grade and shall be firmly held in place by adequate stakes and bracing.

Forms with height greater than the thickness of the concrete may be used if the upper edge is set accurately to line and grade and the subgrade is excavated to meet the bottom edge of the form in a slope not steeper than one vertical to four horizontal. The extra concrete required for the extra depth shall be furnished by the Contractor without extra compensation.

E. Placing Concrete.
Concrete shall be placed to provide for construction of the curb and gutter as an integral unit. Curb and gutter shall be consolidated during placement with internal vibration operating at a frequency between 3,500 vibrations per minute (vpm) and 8,000 vpm.

F. Finishing.
After concrete has been consolidated and face forms have been removed, the surface shall be finished to a uniform texture. Edges adjacent to all forms and expansion and contraction joints shall be edged with a suitable edging tool.

The finished surface shall conform to the lines and grades shown in the contract documents. The gutters shall drain as indicated in the contract documents and shall not have depressions which trap water.

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

H. Joints.
The Contractor shall construct joints for PCC curb and gutter in accordance with Section 2301 and the contract documents.

2512.05 METHOD OF MEASUREMENT.
The Engineer will determine the number of linear feet (the length to the nearest 0.1 m) of concrete curb or curb and gutter by measuring along the face of the curb at the gutter line.

2512.06 BASIS OF PAYMENT.
For the number of linear feet (meters) of concrete curb or curb and gutter constructed and accepted, measured as provided above, the Contractor will be paid the contract unit price per linear foot (meter). This payment shall be full compensation for furnishing all materials; preparation of subgrade; and placing, compacting, finishing, and curing the concrete curb or curb and gutter.