(A) All public sidewalks shall be of concrete and shall be laid in sections or blocks of five feet in length and five and one-third feet in width, with a slope of one-fourth of an inch to the foot toward the center of the street adjacent to which they are laid, and with a space of 18 inches between the inner edge of the sidewalk and the property line of lots on which they abut. Unless otherwise ordered by the Director of Public Works, the surface of the ground shall be graded by being excavated or filled as the case may require so as to permit the walk to be laid to the grade established by the Director of Public Works and shall be smoothed, thoroughly wetted and compacted at nine inches below proposed grade of sidewalk. On ground thus prepared shall be placed an insulating or drainage course of sand or washed pit run gravel containing no pebbles larger than three-quarters of an inch in maximum dimension, rolled or tamped to a compacted thickness of four inches. Over this drainage course shall be placed a five inch thick slab of concrete as above described.
(B) Concrete shall be a mixture of portland cement, fine and coarse aggregates and clean water meeting requirements of the following current specifications of the American Society for Testing Materials:
Portland cement | ASTM C-175, Type I-A (Air Entraining) |
Fine aggregate | ASTM C-33 |
Coarse aggregate | ASTM C-33, Size 57 |
(C) Water shall be clean, clear and free from acid, alkali, oil or organic matter. Concrete shall be mixed in proportions of available aggregates, cementitious material and water as will produce a concrete which will have a compressive strength of 3,000# per square inch at 28 days when tested in accordance with ASTM Specifications C-39, except that not less than five and one-half sacks of cement be used per cubic yard of concrete. Water-cement ratio shall be such that will produce a slump of not less than two inches nor more than six inches when tested in accordance with ASTM C-143.
(D) Concrete shall be mixed for at least one and one-half minutes in approved, batch type, mechanical mixing equipment with water measuring and timing devices. Quantities placed in mixer shall be measured by equivalent weight with due allowances for moisture in aggregates. Use of plant mixed concrete, delivered to the job in revolving drum mixer trucks, will be approved, if factual evidence is submitted establishing adequacy of proposed plant’s equipment and facilities for consistent production of required concretes. Factual evidence will also be required establishing producer’s reputation for meeting specifications, for making prompt and timely deliveries and for general reliability. Plant mixed concrete shall meet ASTM Specifications C-94, except that revolving drum truck delivery will be required.
(E) Concrete shall be placed not more than 30 minutes after discharge from mixer, screeded off to proper slope and thickness and thoroughly worked with floats. When concrete has reached proper hardness, it shall be troweled to a true, smooth surface, free from unevenness of any kind.
(F) After troweling, surface of sidewalk shall be brushed or floated lightly to ensure a non-slip surface.
(G) As soon as concrete has taken an initial set, sidewalks shall be given a sprayed application of a membrane coating to prevent rapid evaporation of water during curing period. Membrane coating shall meet requirements of ASTM Specifications C-309, Type 1, containing a fugitive color. Apply membrane as directed by manufacturer but at a rate of not less than one gallon to 200 square feet of surface.
(1959 Code, § 31-16)