A. The first or lower layer of concrete shall be not less than three and one-quarter inches in thickness, and up to within three-quarters of an inch of grade after thorough tamping. It shall be formed of a good, merchantable quality of portland cement mixed with clean gravel, which has been screened through a screen of two-inch mesh, and clean sand (the sand and gravel in about equal parts), entirely free from dirt, in the proportion of one part of cement measured in the original package to seven parts of sand and gravel. The cement, sand and gravel are to be thoroughly mixed dry until the mass is of an even color, and water added thereafter by sprinkling, the mixing to be continued until every particle of sand and gravel is coated with cement, and the mass is sufficiently wet. All is to be put in place and finished before the cement has taken the initial set.

B. The top layer of three-quarters of an inch shall be composed of good merchantable portland cement and fine screened gravel mixed in the proportion of one part cement measured in the original package to one and one-half parts of screened gravel. These are to be thoroughly mixed dry until the mass is of an even color, then to be sprinkled with water and again mixed so that the gravel particles are all coated with cement.

C. The top layer shall be trowelled to a plain, smooth and even surface on the established grade and line as given by the city engineer, and to be lined into blocks not to exceed nine square feet in area.

D. The work when completed shall be properly protected from sun, frost and travel or use until the surface is hard. (Ord. 12-03, 2012)