The following material specifications shall apply for concrete driveway aprons, patios or other slab on grade installations:
(a) Cement. The cement used in concrete shall be Portland cement, a well-known brand, and shall be subject to testing as required by the Director of Public Service, Building Commissioner or City Engineer in accordance with Standard Methods of Sampling and Testing of the American Society for Testing Materials.
(b) Grading. Excavation of subgrade shall include removal of all earth, loam, shale, rock, roots, briars and undergrowth. All spongy material shall be removed. Fills are to be made with gravel or other material acceptable to the Director of Public Service, Building Commissioner or City Engineer.
(c) Forms. Concrete shall be thoroughly mixed before being deposited in clean steel or wooden forms adequately braced to prevent distorting from the specified dimensions. All forms shall be of a size sufficient to produce a driveway or apron of a minimum thickness as required in Section 1377.09(l) of the Housing Code.
(d) Placing Concrete.
(1) The concrete shall be thoroughly tamped and consolidated so that none of the stone appears on the surface. The forms must be kept clean and shall be coated with suitable oil before filling with concrete.
(2) Foundation beds shall be sprinkled immediately prior to depositing the concrete.
(3) Concrete when mixed shall be rapidly deposited in the forms and any concrete not in final position within thirty minutes after completion of the mixing shall be discarded. Under no circumstances shall concrete be used that has partially set and the remixing of such materials is prohibited. The concrete shall be deposited between bulkheads of a uniform thickness and to the full depth and width; irregular or sloping surfaces shall be avoided. The concrete, after being placed, shall be thoroughly compacted and brought to the proper pitch and grade with templet or straight edge.
(4) Immediately prior to the finishing of the surface, the concrete shall be cut into slabs not longer than ten feet on any one side. The joints shall be cut through the full thickness and the opening so made shall be filled with clean, dry sand, well rammed into place. The joints shall be formed by a cutting tool or other means satisfactory to the Director of Public Service, Building Commissioner or City Engineer. The markings in the surface at these joints shall not be more than one-fourth of an inch deep. All edges shall be rounded with an approved edging tool to a radius of one-fourth of an inch.
(e) Surface Finish. The finish shall immediately follow the placing and compaction of the concrete. Unless otherwise ordered by the Director of Public Service, Building Commissioner or City Engineer, a finish produced by rubbing with wood floats with a uniform texture shall be required. The surface shall be free from depressions or inequalities. The application of dry cement to hasten drying of the surface is prohibited.
(f) Curing and Protecting. In rainy weather, the concrete shall be protected as soon as it is finished. In hot or dry weather, the contractor shall keep the concrete wet. Sprinkling shall begin as soon as the concrete is set sufficiently to prevent pitting and shall be continued at such intervals as weather conditions may require or the Director of Public Service, Building Commissioner or City Engineer may direct.
(g) Expansion Joints. Prepared strips of bitumen and fiber or mineral aggregate shall be placed in concrete at intervals of at least 20 feet, also at ends where the concrete abuts curbing or other lateral walks and along the building line where the concrete is laid full width from the curb to the building or other structures. Similar joints shall be placed around water meter covers, gas boxes, hydrants, lamp standards or other fixed objects projecting through the concrete. All strips shall be one-fourth of an inch in thickness, except for transverse joints when the temperature is below 70o Fahrenheit, in which event the strips shall be one-half of an inch in thickness. The top of the strip shall be cut off flush with the top of the concrete.
(Ord. 2006-197. Passed 10-3-06.)