Sidewalks shall be constructed of Portland cement concrete to a thickness of five inches (5"). Concrete for such sidewalks shall have a minimum twenty eight (28) day compressive strength of four thousand (4,000) pounds, and shall contain not less than three percent (3%) nor more than six percent (6%) entrained air. Slump shall be not less than two inches (2") nor more than four inches (4"). (Ord. 0-77-02, 2-7-1977)