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in the forms shall be by vibration or other acceptable methods. Forms shall be left in place for 24 hours or until the concrete has set sufficiently so that they can be removed without injury to the curbing. Upon removal of the forms, the exposed curbing face shall be immediately rubbed to a uniform surface. Rubbing shall be accomplished by the use of water and a carborundum brick. For the purpose of matching adjacent concrete finishes or for other reasons, the Engineer may permit other methods of finishing. No plastering will be permitted.

(d) Sections.—Curbing shall be constructed in sections having a uniform length of ten feet, unless otherwise ordered. Sections shall be separated by open joints 18-inch wide except at expansion joints.

(e) Expansion joints.—Expansion joints shall be formed at the intervals shown on the plans using a preformed expansion joint filler having a thickness of 34-inch. When the curb is constructed adjacent to or on concrete pavement, expansion joints shall be located opposite or at expansion joints in the pavement.

(f) Curing.Immediately upon completion of the rubbing, the curbing shall be moistened and kept moist for three days, or the curbing shall be cured by the use of membrane forming material. The method and details of curing shall be subject to the approval of the Engineer.

(g) Backfilling.After the concrete has set sufficiently, the spaces in front and back of the curb shall be refilled to the required elevation with suitable material, which shall be thoroughly tamped, in layers of not more than six inches.

(h) Curb machine.—With the approval of the Engineer, the curb may be constructed by the use of a curb forming machine.

(i) Curb template.-If approved by the Engineer, the exposed curb face may be constructed and finished by use of trowel-type templates, shaped to produce the desired contours when operated along approved forms set to the established lines and grades.

While the concrete is green, the top, front, or other exposed surfaces of the curb or combined curb and gutter shall be floated with a moist wooden float. Clean water shall be applied ahead of the float whenever necessary. Form marks and any other irregularities shall be removed.

609.05 Precast Concrete Curbing. The installation of precast concrete curbing shall meet the requirements of subsection 609.03.

609.06 Reflecting Concrete Curbing. Construction methods for this item shall conform to the requirements of subsection 609.04 with the following supplements :

The reflecting surface of the curbing shall be a mortar mix consisting of 1 part white portland cement to 19 parts of light colored, washed mortar sand. This mortar mix shall have a thickness of approximately one inch. Alternatively the entire curbing may be constructed of concrete with white portland cement.

Washed mortar sand shall meet all the requirements for mortar sand and shall be of a light color satisfactory to the Engineer. The reflecting surface mortar shall be placed immediately after placing of the base concrete. In no case shall more than twenty minutes elapse between the placing of the base concrete and the placing of the reflecting surface.

Scoring or surface deformation and finish of the reflecting surface shall conform to the details shown on the plans.

609.07 Bituminous Concrete Curbing.

(a) Excavation.—Excavation shall conform to the requirements of subsection 609.03(a).

(b) Preparation of bed.—When curbing is to be constructed on a fresh laid bituminous surface, the curb may be laid only after the surface has been cleaned.

When curbing is to be constructed on a cured or aged portland cement concrete base, bituminous pavement or bituminous treated base, the bed shall be thoroughly swept and cleaned by compressed air. The surface shall be thoroughly dried and, immediately prior to placing of the bituminous mixture, shall receive a tack coat of bituminous materials of the type and grade specified in the contract. The rate of application of the tack coat material shall be between 0.05 to 0.15 gallons per square yard of surface. In the application of this tack coat, the Contractor shall prevent the spread of this tack coat to areas outside of the area to be occupied by the curb.

(c) Placing.–Bituminous curbing shall be constructed by use of a self-propelled automatic curber or curb machine or a paver with curbing attachments.

The automatic curber or machine shall meet the following requirements and shall be approved prior to its use.

1. The weight of the machine shall be such that required compaction is obtained without the machine riding above the bed on which curbing is constructed.

2. The machine shall form curbing that is uniform in texture, shape and density.

3. The Engineer may permit the construction of curbing by means other than the automatic curber or machine, when short sections or sections with short radii are required, or for such other reasons as may seem to him to be warranted. The resulting curbing shall conform in all respects to the curbing produced by the use of the machine.

(d) Painting and sealing.When sealing or painting is required, it shall be performed only on a curbing which is clean and dry and which has reached and ambient temperature.

(e) Backfilling.–Backfilling shall conform to the requirements of subsection 609.04(g).

609.08 Resetting Curb.

(a) Salvage of curbing.—The Contractor shall carefully remove, store and clean any curbing specified for resetting. The Contractor shall replace any existing curbing that is to be reset, which is lost, damaged or destroyed as a result of his operations, or because of his failure to store and protect it in a manner that would eliminate its loss or damage.

(b) Excavation.—Excavation and bedding shall conform to the requirements of subsection 609.03(a).

(c) Resetting curb.—The curb shall be set on a firm bed with the front top arris line conforming to the required line and grade. All sections of curbing shall be set so that the maximum opening between adjacent sections is not more than 34-inch wide for the entire exposed top and face. Any dressing of the ends of the curbing necessary to meet this requirement shall be done by the Contractor.

After the curb has been set, the joints shall be completely filled with mortar as specified.

(d) Backfilling.–The spaces in front and back of the curb shall be refilled to the required elevation with suitable material. This material shall be thoroughly tamped in layers of not over 6 inches in depth.

(e) Cutting and fitting.–Cutting or fitting shall be done as necessary to install the curbing at the locations directed.

Method of Measurement

609.09 Curbing, both new and reset, will be measured by the linear foot along the front face of the section at the finished grade elevation. Combination curb and gutter will be measured along the face of the curb. No deduction in length will be made for drainage structures installed in the curbing such as catch basins, drop inlets, etc.

Bed course material will be measured by the ton or by the cubic yard.

Basis of Payment 609.10 The accepted quantities of curbing, including, excavation, dowels, expansion material, reinforcing steel and

bedding will be paid for at the contract unit price per linear foot for each kind and type of curbing specified and per ton or cubic yard for bed course material complete in place. Payment will be made under: Pay item

Pay unit
609 (1) Portland cement concrete
curb,-inch depth

Linear foot.
609 (2) Portland cement concrete
gutter

Linear foot.
609(3) Portland cement concrete

curb and gutter,-inch depth.- Linear foot.
609 (4) Bituminous concrete curb,
-inch depth

Linear foot.
609 (5) Stone curb,—inch depth

Linear foot. 609 (6) Reset curb, type

Linear foot. 609 (7) Bed course material

Cubic yard/ton. Letter suffixes will be added to the item numbers to differentiate between various types or depths of item to be

bid upon.

Section 610.-STONE MASONRY STRUCTURES

Description 610.01 Scope. This work shall consist of the construction of stone masonry structures and the stone masonry portions of composite structures, in accordance with these specifications and in reasonably close conformity with the lines, grades, dimensions, and design shown on the plans or directed by the Engineer.

610.02 Classes of Masonry. The class of masonry required for each part of a structure will be that indicated on the plans and described herein.

Cement Rubble Masonry shall consist of roughly dressed stones of various sizes and shapes laid in random courses in cement mortar, as specified in this section.

Class A and Class B Masonry shall consist of stones shaped, dressed, and laid broken-coursed in cement mortar in accordance with the requirements specified in this section for the designated class.

Dimensioned Masonry shall consist of broken-coursed ashlar masonry composed of stones having two or more dimensions shown on the plans and in accordance with the requirements of this section.

Materials

610.03 Stone. The stone shall be sound and durable, quarried by approved methods, and will be subject to the Engineer's approval. It shall preferably be native to the vicinity of the work and shall be of a kind that previous use has proven to be satisfactory for the specified purpose. (Vicinity of the work shall be understood to mean within a radius of approximately 50 miles.) The stones shall be properly protected at all times.

In addition to the above requirements, stone for dimensioned masonry shall be free of reeds, rifts, seams, laminations, and minerals which, by weathering, would cause discoloration or deterioration.

(a) Sizes and shapes.—Each stone shall be free from depressions and projections that might weaken it or prevent it from being properly bedded, and shall be of such shape as will meet both architecturally and structurally the requirements for the class of masonry specified.

When dimensions for stones are shown on the plans, the stones shall be of the size shown. When no dimensions are shown on the plans, the stones shall be furnished in the sizes and face areas necessary to produce the general characteristics and appearance as indicated on the plans.

In general, stones shall have thicknesses of not less than 5 inches, widths of not less than 142 times their respective thicknesses, with minimum width of 12 inches, and lengths of not less than 142 times their respective widths. Where headers are required their lengths shall be not less than the width of bed of the widest adjacent stretcher plus 12 inches.

At least 50 percent of the total volume of the masonry shall be of stone having a volume of at least 1 cubic foot each.

(b) Dressing.–The stone shall be dressed to remove any thin or weak portions. Face stones shall be dressed to provide bed and joint lines with a maximum variation from true line as follows: (1) Cement rubble masonry

142 inches. (2) Class B masonry

34 inch. (3) Class A masonry

44 inch. (4) Dimensioned masonry

Reasonably true. (c) Bed surfaces.—Bed surfaces of face stones shall be normal to the faces of the stones for about 3 inches and from this point may depart from normal not to exceed 1 inch in 12

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