(a) Upon the subgrade, there shall be laid a bed of concrete, of the depth specified in the ordinance ordering the work, composed of cement and stone fixed as follows; provided that, if the ordering ordinance does not specify the depth of concrete, then it shall be six (6) inches in depth.
(b) The cement used must be a standard brand portland cement meeting the requirements and specifications as adopted by the American Society for Testing Materials.
(c) The sand must be coarse, clean and sharp, and equal in all respects to the Ohio River Washed Sand.
(d) The stones shall be equal to the native gray limestone or river gravel and must be free from clay, earth or other foreign substances. They shall be of a size that will pass a 2½ screen and be retained on a ½ screen. The stone preferable for use shall be a combination of the ¾-inch stone in equal proportions with the 1½-inch stone.
(e) Cement and aggregates shall be accurately measured by volume or weight. The cement shall be measured as packed by the manufacturer in sacks containing not less than ninety-four (94) pounds, being considered one (1) cubic foot. When volume measurements are used, the fine and coarse aggregates shall be measured in specifically prepared measuring boxes. Such boxes shall be accurately constructed to specific cubic content and of uniform size. If aggregates are measured by weight, an approved type of modern aggregates measuring device, equipped with measuring lines and built-in scales, designed specifically for such purpose, shall be used.
(f) Concrete delivered from a central mixing plant shall be measured by weight in accordance with the provisions as above stated. The urban county engineer shall have free access to the mixing plant and the right to inspect the plant loading hopper and the materials at any and all times. No materials shall be measured in wheel barrows. All empty cement sacks shall be handled under the supervision of the urban county engineer. If concrete is mixed at the scene of the work, an approved batch mixer, having means of measuring water supplied to each batch, shall be used. If concrete is delivered from a central plant in batch mixers, sufficient units must be used to ensure steady delivery of concrete to the job. Not more than six (6) gallons of water per bag of cement shall be used. (For concrete paving, not more than five (5) gallons of water per bag of cement shall be used.) Concrete shall be mixed for at least one (1) minute after all materials have been placed in the mixer drum, during which time, the drum shall make from fifteen (15) to twenty (20) revolutions. Overloading the mixer drum will not be permitted. The concrete shall be finished to conform to a line parallel to and the required distance below the surface of the proposed brick or asphalt surface, by use of a template or strike-off board conforming to the proper curvature of the proposed surface and of such weight and design as commonly used for the purpose of finishing concrete paving. After the concrete has been struck-off as specified, the entire surface shall be roughened by use of coarse stiff brooms, sufficiently to eliminate smooth or slick spots. Concrete shall consist of one (1) part cement, two (2) parts sand and three and one-half (3½) parts crushed limestone or gravel. Reinforcing center strips and expansion joints will be specified upon the plans or written into the contract and specifications for the particular job.
(g) No concrete job is to be laid when the temperature is below thirty-five (35) degrees Fahrenheit without the written consent of the urban county engineer; and in the event of laying below thirty-five (35) degrees Fahrenheit, the contractor must protect the concrete from freezing. The contractor will be held liable for all damages to the concrete base, and he must protect same from travel for a period of ten (10) days after it is laid and must at all times protect it from use unless granted permission by the urban county engineer.