11.04.042   Specifications for installation of concrete sidewalks and driveways.
   A.   Concrete Sidewalks. All new sidewalk construction to be located on city right-of-way shall be constructed to a four-inch minimum depth on a thoroughly watered and rolled subgrade. The subgrade shall be compacted to a field density of ninety percent of maximum laboratory density. All sidewalks shall have a standard width of 5.0 feet. Any sidewalks constructed with a different width shall be approved by the city's public works director prior to construction.
   B.   Concrete Driveways.
      1.   All new concrete driveway construction to be located on city right-of-way shall be constructed to a six-inch minimum depth on a thoroughly watered and rolled subgrade. The subgrade shall be compacted to a field density of ninety-five percent of maximum laboratory density. Welded wire mesh (6x6 10/10) shall be placed in the concrete driveway slab.
      2.   Where there is an existing curb which must be removed,  the curb shall be cut with a cement power saw at the point the remaining curb adjoins the new driveway. The joint where the remaining curb joins the new driveway shall be connected with dowling of one-half-inch rebar and not less than six inches in length. The driveway will be designed in a manner in which the gutter elevation and slope will not be changed and drainage and flow of water will not be impeded or reduced. In addition, driveway plans shall be furnished by the applicant at the time of obtaining permit.
   C.   Materials.  Class DD Portland cement concrete shall be utilized.  This class of concrete includes the following mix design:
      Maximum aggregate size   3/4 in.
      Minimum concrete content (94 lb. bag)   5.5 sacks/cy
      Minimum required 7-day compressive strength   3,000 lb/sq.in.
      Maximum water content per bag   6.0 gal.
      Slump   1-1/2 to 3 in.
      Required air content   5 to 7 percent
   D.   Erecting Forms. Forms, either of wood or steel, shall be staked securely in place,  true to line and grade. 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 of the established grade. Forms shall be clean and well oiled prior to setting in place. Immediately prior to placing the concrete,  forms shall be inspected by the public works director for proper grading, alignment and rigid construction. Adjustments and repairs as needed shall be completed before placing concrete.
   E.   Placing Concrete. The subgrade shall be graded, compacted and dampened 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.
   F.   Stripping Forms and Finishing.
      1.   Forms may be removed on the day following the pour if the concrete is sufficiently set so 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 a curing compound.
      2.   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 has hardened sufficiently, the surface shall be given a broom finish. The broom shall be of an approved type. The strokes shall be square across the concrete from edge to edge with adjacent strokes overlapped. Strokes shall be made without tearing the concrete. The broomed finish shall produce regular corrugations not over one-eighth inch in depth.
   G.   Protection and Curing.
      1.   Concrete shall be protected from the loss of moisture as soon as possible after placement,  and this protection shall be continued for a period of at least three days. This protection shall consist of some type of water cure, either by ponding, sprinkling, wet sand or earth, or wet burlap, whenever possible.  Where water curing is impossible, approved curing compounds may be substituted therefor. On vertical surfaces, forms should be left in place as long as practical and consistent with construction schedules to retain moisture in the concrete.
      2.   When the low temperatures are expected to drop below freezing and/or the temperatures of the day are expected to remain below forty degrees F, the concrete shall be enclosed and protected in such a way that the air surrounding the fresh concrete can be kept at a temperature of not less than sixty degrees F for a period of three days, and above freezing for an additional three days. Under extremely cold conditions, heating equipment may be required, in addition to housing and covering. When heating is necessary to maintain proper curing temperatures, moisture should be introduced to prevent excessive drying of the concrete. At the termination of the heating period, care should be taken to see that a sudden drastic change in the temperature of the concrete does not take place.
   H.   Transverse expansion joints one-half-inch thick shall be provided at all sidewalk returns and opposite expansion joints in the adjacent curb. Where curbs are not adjacent, expansion joints shall be installed at intervals of fifty feet. Expansion joints shall also be installed where sidewalks about any rigid structure such as curbs, buildings, driveways, etc. Expansion joint material shall consist of bituminous preformed joint filler conforming to AASHO Designation M33 and shall be installed to the full depth of the sidewalk or driveway. Construction joints shall be formed in the fresh concrete and shall be located every five feet.
(Ord. 387 § 1,  1983; Ord. 373 § 3, 1981; Ord.  318 § 4A,  1974).