Concrete curbing shall be permitted to be constructed along the sidewalks of the City and the material used in such construction shall be as follows:
A. Excavations shall first be made to a depth not less than two feet six inches from the top of the finished curb and in width not less than 14 times the width of the curb on the top surface thereof, when finished.
B. The materials thereof, which shall be of a quality satisfactory to the Director of Public Works, shall consist of American Portland cement, clean sharp sand, and crushed stone or slag which shall be hard, clean and free from dust or earth, run of the crusher, not exceeding one inch in its largest dimension.
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C. The proportions of mixture for concrete shall not be less than one part of cement, three parts of sand and five parts of crushed stone or hard slag and for mortar for the finishing coat, not less than one part of cement and no more than two parts of sand.
D. The mixing, if done by hand labor, shall consist of first mixing the cement and sand dry until a uniform color of mixture is secured, after which the crusher stone shall be added, then wetted and turned over until every particle is thoroughly coated with mortar. Sufficient water shall be used so that only moderate tamping is required after the concrete is placed. If done by machine, the method shall be approved by the Director of Public Works.
E. The mortar for the surface or finishing coat shall be applied with the concrete itself by exercising care in placing the concrete against the forms employed so as to push back the larger particles in the mixture by use of a wide pronged fork, and by tamping the large particles down gently below the top surface. Any small quantity of mortar that may be required for the finishing shall be applied while the concrete is wet and only enough to smooth the surface.
18. Editor's Note: Amended during codification (see Ch. 1, General Provisions, Part 2).