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1. Structural Concrete: Structural concrete shall conform to the requirements of section 03310, in appendix A to ordinance 190, on file in the office of the city clerk-treasurer.
2. Reinforcing Steel: Reinforcing steel shall conform to the requirements of section 03210, in appendix A to ordinance 190, on file in the office of the city clerk-treasurer.
3. Preformed Expansion Joint Materials: Joint material shall comply with the requirements of AASHTO M-213, in appendix A to ordinance 190, on file in the office of the city clerk-treasurer. (Ord. 13.24; amd. 2006 Code)
B. Construction Methods:
a. It is the intent of this specification to require machine laid or hand formed combined concrete curb and gutter.
b. The curb machine shall be a self-propelled type equipped with a material hopper, distribution screw and adjustable curb forming devices capable of laying and compacting the concrete mix to the lines, grades and cross section as shown on the plans.
c. Curb machines may be designed to utilize steel forms, or may be of the slip form extruded concrete type. (Ord. 13.24)
2. Subgrade Preparation:
a. Excavation for the construction shall be the required depth, and the subgrade or base course upon which the concrete is to be placed shall have a firm and even surface, and shall be compacted as called for in section 02230, in appendix A to ordinance 190, on file in the office of the city clerk-treasurer. (Ord. 13.24; amd. 2006 Code)
b. Excavation shall be as required to permit placing of curb, gutter and/or combined curb and gutter to the lines as shown on the plans.
3. Erecting Forms:
a. Steel or wooden forms shall be staked securely in place, true to line and grade.
b. Sufficient support shall be given to the form to prevent movement in any direction, resulting from the weight of the concrete or the concrete placement. Forms shall not be set until the subgrade has been compacted within one inch (1") of the established grade. Forms shall be clean and well oiled prior to setting in place.
c. When set, the top of the form shall not depart from plan elevation or design grade more than one-fourth inch (1/4") when checked with a ten foot (10') straightedge. The alignment shall not vary more than one-half inch (1/2") in ten feet (10'). Immediately prior to placing the concrete, forms shall be carefully inspected for proper grading, alignment, and rigid construction. Adjustments and repairs as needed shall be completed before placing concrete.
4. Placing Concrete:
a. The subgrade shall be properly compacted and brought to specified grade before placing concrete. The subgrade shall be thoroughly dampened immediately prior to the placement of the concrete. Concrete shall be spaded and tamped thoroughly into the forms to provide a dense, compacted, concrete free of rock pockets. The exposed surfaces shall be floated, finished and broomed.
b. The rate of concrete placement shall not exceed the rate at which the various placing and finishing operations can be performed in accordance with these specifications. (Ord. 13.24)
c. If the concrete is to be placed by the extruded method, the contractor shall demonstrate to the satisfaction of the engineer or city superintendent that the machine is capable of placing a dense, uniformly compacted concrete to exact section as per the tolerances in subsection C of this section. (Ord. 13.24; amd. Ord. 2.32)
5. Stripping Forms And Finishing:
a. Removal Of Forms: Forms may be removed on the day following pour if the concrete is sufficiently set that removal will be without danger of chipping or spalling. When forms are removed before the expiration of the curing period, the edges of the concrete shall be protected with moist earth, or sprayed with curing compound. All forms shall be cleaned, oiled and examined for defects before they are used again.
b. Broomed Finish: The surface of concrete curbs and gutters shall be finished true to the lines and grades shown on the plans. Concrete shall be worked until the coarse aggregate is forced down into the body of the concrete and no coarse aggregate is exposed. The surface shall then be floated with a wooden float to a smooth and uniform surface. When the concrete in the curb and gutter has hardened sufficiently, the surface shall be given a broom finish. The broom shall be of an approved type. Strokes shall be made without tearing the concrete. The broomed finish shall produce regular corrugations not over one-eighth inch (1/8") in depth.
6. Curing: Curing shall be done in accordance with good construction practice.
7. Joints For Combined Curb And Gutter:
a. Preformed expansion joint material one-half inch (1/2") thick shall be provided in combined curb and gutter at PCs and PTs, and at curb turns at block corners or alley approaches. The joint filler shall be cut to the cross section of the combined curb and gutter.
b. Expansion/contraction joints shall be provided between the expansion joints at not more than fifteen foot (15') intervals. Where shorter sections are necessary for closure, the interval may be less than fifteen feet (15'), but no section shall be less than five feet (5').
c. Construction joints shall, in general, be located at expansion joints. Where it is determined necessary to discontinue placing at locations other than expansion joints, a keyed construction joint shall be located at a contraction joint location.
8. Curb Backfill:
a. The curb backfill to a level of four inches (4") below the top of curb shall be completed before final grading of the subgrade and placement of base courses.
b. In areas where lawns exist, the top four inches (4") of backfill bringing it level up to the top of the curb shall be black loam or good topsoil which is suitable for the growth of lawns. It shall be placed out from the curb a sufficient distance and in an mount to replace turf or lawn removed during installation. Backfill shall be completed by grading to match the existing lawns.
9. Prime And Seal Coat Preparation: The edge of the gutter adjacent to the asphalt surfacing shall be painted with an asphalt prime coat before the pavement surface course is placed. When an asphalt seal coat is specified, the application of oil and cover aggregate shall lap three inches (3") over the gutter to provide a good seal on the joint between the concrete and pavement. (Ord. 13.24)
C. Tolerances: The work shall be performed in a manner which results in a curb and gutter constructed to a specified line and grade, uniform in appearance and structurally sound. Curb and gutter found with unsightly bulges, ridges, low spots in the gutter or other defects shall be removed and replaced at the owner's expense if the engineer or city superintendent considers them to be irreparable. Grade shall not deviate more than one- fourth inch (1/4"), and alignment shall not vary more than one- half inch (1/2") from plan elevation, grade or alignment. Tolerance may be checked by use of survey instruments, straightedges, or water puddling. (Ord. 13.24; amd. Ord. 2.32)