Sec. 42-136. - Application of subdivision.

This subdivision applies to concrete curbs.

Sec. 42-137. - Dimensions, etc.

Concrete curbs shall be at least eight inches in width and 20 inches in depth. Concrete curbs shall be constructed entirely separate from the sidewalk, except where a six-inch driveway or cross drive is constructed adjacent to the curb. In such cases the curb and sidewalk driveway or cross drive may be integrally constructed, each in accordance with the specifications.

(Code 1968, § 45-56)

Sec. 42-138. - Excavations; replacement of material; ramming, etc., of subgrade.

Excavation for the construction of all curbs shall be to a depth of 20 inches below the established grade of the finished curb. All soft and other unsuitable material shall be removed and replaced with satisfactory material. The subgrade shall be thoroughly compacted by ramming and finished to a uniform surface.

(Code 1968, § 45-57)

Sec. 42-139. - Care of trees.

Trees shall not be injured while concrete curbs are being constructed, but roots of trees which in any way interfere with the construction work and its maintenance in a proper manner may be cut away under the supervision of the city forester.

(Code 1968, § 45-58)

Sec. 42-140. - Forms.

The forms for concrete curbs shall be of wood or metal, smooth, free from warp, of sufficient strength to resist springing out of shape, and of a depth to conform to the depth of the proposed work. The forms shall be well staked and set to the established lines, the upper edges conforming to the grade of the finished curb. All wood forms shall be thoroughly wetted and metal forms oiled before depositing any material against them. All mortar and dirt shall be removed from forms that have been previously used.

(Code 1968, § 45-59)

Sec. 42-141. - Wetting of foundation.

The foundation for curbs shall be moistened before the concrete is placed.

(Code 1968, § 45-60)

Sec. 42-142. - General requirements for cement.

Cement used in work regulated by this subdivision shall meet the requirements of the current Standard Specifications for Portland Cement of the American Society for Testing Materials.

(Code 1968, § 45-61)

Sec. 42-143. - Stone dust or sand.

The stone dust or sand used in work regulated by this subdivision shall be reasonably clean and sharp with its grains graded in size from fine to coarse, containing no more than three percent of clay and loam, and free from all vegetable matter or other impurities. Bank run sand shall not be used.

(Code 1968, § 45-62)

Sec. 42-144. - Coarse aggregate, etc.

Coarse aggregate shall consist of clean, durable, crushed rock, pebbles or crushed blast furnace slag, graded in size, free from vegetable or other organic matter, and shall contain no soft, flat or elongated particles. If necessary, it shall be screened and washed to produce this product. The slag shall not contain more than 1½ percent of sulphur as sulphides. The size of the coarse aggregate shall range from one inch down, not more than five percent passing a screen having four meshes per linear inch, and no intermediate sizes shall be removed. Bank run gravel shall not be used.

(Code 1968, § 45-63)

Sec. 42-145. - Concrete mixture proportions generally.

(a)

Unless otherwise specifically approved by the department of public works, the concrete for the curbs and cross drives shall be central-mix concrete that will show a compressive strength under a 28-day test of not less than 3,000 pounds per square inch. The compression test of the concrete shall be made in cylinders having a diameter equal to one-half the length; the standard cylinder of concrete shall be six inches in diameter and 12 inches in length. When ordering central-mix concrete for sidewalk curbing and paving, the contractor shall specify that the delivery slip for the material shall show the name of the company furnishing the material, the strength of the concrete, percentage of calcium chloride, if any, aggregate and slump of the concrete delivered. When requested to do so, the contractor or his representative on the work shall present such delivery slip or slips to the code enforcement officer or his representative.

(b)

If, with the approval of the department of public works, concrete for curbs and cross drives is mixed directly upon the work, such concrete shall be composed of one part by volume of Portland cement, 1½ parts by volume of sand or stone dust, and three parts by volume of gravel, crushed stone or slag.

(Code 1968, § 45-64)

Sec. 42-146. - Method of measuring concrete.

The method of measuring the materials for the concrete, including water, shall be one which will insure separate and uniform proportions of each of the materials at all times. A sack of Portland cement, 94 pounds net, shall be considered one cubic foot.

(Code 1968, § 45-65)

Sec. 42-147. - Water.

Water shall be clean, free from oil, acid, alkali, vegetable or other organic matter.

(Code 1968, § 45-66)

Sec. 42-148. - Joints generally.

The curb shall be built in sections separated by clean joints. The length of sections shall be six feet when constructed on fills and not over ten feet in excavation; except, that shorter sections may be used for closures, but in no case shall the sections be less than four feet in length. The joint between curb sections shall not exceed one-quarter inch in thickness and shall be filled with an approved "joint filler."

(Code 1968, § 45-67)

Sec. 42-149. - Surfacing and finishing.

The concrete shall be tamped sufficiently to bring the mortar to the surface, after which it shall be struck off with a wooden template shaped to produce the required cross section and then finished smooth and even by means of a wooden float. The wearing surface shall be formed without the addition of mortar plaster. The forms for the face of the curb shall be removed within 24 hours after the concrete has been placed. The concrete adjacent to each transverse joint shall be finished with a split wooden float which will insure finishing both sides to the same grades, after which the edges of the concrete at the joints shall be rounded with an approved edging tool to a radius not less than one-quarter inch nor more than one-half inch. Plastering will not be permitted, but minor defects shall be remedied by filling with mortar, composed of one part by volume of cement and two parts by volume of sand or stone dust applied with a wooden float. The top and face of the curb shall be finished while the concrete is still green by rubbing with a wet brick or block of wood until the surface is smooth.

(Code 1968, § 45-68)

Sec. 42-150. - Expansion joints.

Expansion joints one-quarter inch in thickness shall be provided at each curb return. These joints shall be made by inserting tar paper or felt to the entire thickness and depth of the curb.

(Code 1968, § 45-69)

Sec. 42-151. - Adjoining curbs to be repaired.

Before a concrete walk paving is placed next to the curb, the contractor shall, at the owner's expense, make the necessary repairs to any portion of the curb, either stone or concrete, that does not meet or conform to specifications of the department of public works for concrete curbs.

(Code 1968, § 45-70)

Sec. 42-152. - Curing.

(a)

When the concrete curb or curb work is completed, or at the end of each day's work, the concrete shall be protected and cured for at least two days.

(b)

The curing shall be done by covering the finished concrete or curb, after final set, with burlap, canvas, sisal-kraft, etc., and the covering shall be kept thoroughly wet for at least two days; or, in lieu of the foregoing the concrete or curb may be sprayed, at the rate of one gallon for each 200 square feet, with "Clearkure," "Masterkure" or an approved equal liquid curing compound acceptable to the department of public works.

(Code 1968, § 45-71)

Sec. 42-153. - Edges to be backed up.

At the completion of the entire work, all edges of the curb shall be backed up level with the grade of the curb so as to preserve the pavement and present a neat appearance.

(Code 1968, § 45-72)

Secs. 42-154—42-170. - Reserved.