All labor, material, equipment and tools necessary for the construction of all concrete sidewalks shall be furnished and placed in compliance with the following specifications:
A. Dimensions: All walks constructed in front of and siding residentially zoned property shall be five feet (5') in width and five inches (5") in thickness. Walks constructed in front of and siding business or industrially zoned property shall be six feet (6') in width and five inches (5") in thickness. Location of walks shall be one foot (1') streetward from the right-of-way line, unless otherwise authorized by the City.
B. Grade: The standard grade for sidewalk shall be at a slope not less than one-fourth inch (1/4") per foot (1') of parkway width where curb is existing. Where conditions require, this standard may be modified as directed by the Director of Health and Inspectional Services. Where no curbs exist, the grade shall be established by the City.
C. Weather Conditions: No sidewalk shall be installed when the temperature is forty five degrees (45°) or lower or when the United States Weather Bureau forecasts a temperature of less than forty degrees (40°) within seventy two (72) hours after pouring concrete.
D. Materials for Concrete:
1. All materials to be incorporated in concrete placed under these specifications shall comply with the following specifications:
a. Portland Cement: Portland Cement shall conform to Type 1 of the standard specifications and tests for Portland cement (Serial Designation C150-56) of the American Society for Testing Materials and subsequent revisions thereto.
b. Fine Aggregate: Fine aggregate shall consist of sand having clean, hard, durable, uncoated grains, free from deleterious substances and shall range in size from fine to coarse within the limits indicated below, percentage by weight. Sand shall be obtained from a source known to be in current use on concrete construction:
Passing through No. 4 sieve not less than ninety five percent (95%).
Passing through No. 100 sieve about five percent (5%).
c. Coarse Aggregate: Coarse aggregate shall consist of crushed stone, gravel or other approved inert materials with similar characteristics, or combination thereof, having clean, hard, durable, uncoated particles, free from deleterious matter. It shall range in size from fine to coarse within the following percentages, by weight. Coarse aggregate shall be obtained from a source known to be in current use on concrete construction:
Passing one and one-half inch (11/2") sieve not less than ninety five percent (95%).
Passing No. 4 sieve not more than five percent (5%).
d. Mixing Water: Mixing water shall be clean and shall be free from oil, acid and injurious amounts of vegetable matter, alkalies or other salts.
2. All concrete shall be volume proportioned on the basis of one part Portland cement, two (2) parts of fine aggregate and three and one-half (31/2) parts of coarse aggregate with only enough water added to make a workable mix; except, that all concrete shall contain not less than six (6) sacks of cement per cubic yard. All concrete shall contain four percent (4%) to six percent (6%) of entrained air. Slump shall not exceed four inches (4"). All concrete used shall be subject to satisfactory inspection by the Director of Health and Inspectional Services.
E. Cylinder or Cores: The Director of Health and Inspectional Services may order standard concrete cylinder or cores made of concrete deemed questionable by him. Such cylinder or cores shall be obtained and tested by a reputable testing laboratory approved by the City. Concrete shall have a strength of three thousand five hundred (3,500) pounds per square inch at twenty five (25) days when tested by standard methods.
F. Subgrade:
1. During excavation, all unsuitable material such as black dirt, broken concrete, spoil or any other material deemed unsatisfactory by the Director of Health and Inspectional Services shall be removed from the sidewalk area and a satisfactory subgrade established. Fill under sidewalks shall consist of tamped or rolled sand, gravel or crushed stone, satisfactory to the Director of Health and Inspectional Services.
2. The subgrade shall be tamped or rolled until thoroughly compacted, shall be constructed true to line, grade and cross-section for the bottom of the sidewalk or sidewalk apron and shall be prepared sufficiently wide to accommodate the forms.
G. Embankments: Embankments prepared for walk construction shall be not less than six inches (6") wider on each side than the width of the walk to be installed.
H. Forms:
1. Side forms shall be lumber with a nominal thickness of two inches (2") or of steel of equal rigidity. They shall be held securely in place by stakes or braces, with the top edges true to line and grade. The forms for street sidewalks shall be so set that the slab will have a fall of one inch (1") vertical to four feet (4') horizontal from the edge nearest the property line toward the edge farthest from the property line.
2. Forms for the sidewalk aprons shall be so set that the slab will have a uniform fall between the sidewalk proper and the curb grade. Forms shall be of a depth equivalent to or greater than the thickness of the walk;
I. Laying Concrete: The subgrade or subbase shall be adequately moistened just before the concrete is placed. The concrete shall be placed in successive bate for the entire width of the slab, tamped until all voids are removed and free mortar appears on the surface thoroughly spaded along the edges, struck off to the true grade and finished to a true and even surface with suitable trowels and floats. The surface shall be divided by grooves constructed at right angles to the center line of the sidewalk. These grooves shall extend to one-fourth (1/4) the depth of the sidewalk, shall be not less than one-eighth inch (1/8") or more than one-fourth inch (1/4") in width and shall have the edge rounded one-fourth inch (1/4"). No slab shall be longer than six feet (6') or less than four feet (4') unless otherwise approved by the Director of Health and Inspectional Services. The side edges of the walk shall also be edged with an edging tool, having a one-fourth inch (1/4") radius. The finished sidewalk shall be finally dragged across its width with a brush or the surface otherwise roughened by approved methods to give a nonskid finish.
J. Expansion Joints:
1. Expansion joints, one-half inch (1/2") thick, shall be provided between the sidewalk and all structures, such as light standards, traffic light standards, traffic poles, etc., which extend through the sidewalk.
2. Expansion joints, one inch (1") thick, shall be placed wherever sidewalks abut against concrete driveways, concrete pavements, concrete curb and/or concrete walks.
K. Curing:
1. The concrete shall be cured by protecting it against loss of moisture, rapid temperature change and from rain, flowing water and mechanical injury for a period of not less than three (3) days from the beginning of the curing operation. Moist curing, waterproof paper, white polyethylene sheeting, liquid membrane compound or a combination thereof may be used for curing. Immediately after finishing operations have been completed, the entire surface of the newly laid concrete shall be covered by the curing medium which is applicable to local conditions and approved by the City Engineer. The edge of concrete slabs exposed by the removal of forms shall be protected immediately to provide these surfaces with continuous curing treatment equal to the method selected for curing the slab surface and to prevent injury to pavement edges;
2. The use of a covering material which contains or becomes contaminated with sugar in any form, tannic acid or any other substances considered detrimental to Portland cement will not be permitted. The initial curing medium shall be effective and shall be applied so as to prevent checking, crackling and the appearance of dry spots in the surface of the concrete. The contractor shall have the equipment needed for adequate curing at hand and ready to install before actual concrete placement begins. In all cases in which the curing medium requires the use of water, the curing shall have prior right to all water supply. Failure to provide sufficient cover material of the type selected, failure to maintain saturation for the entire curing period in the moist-curing methods, lack of water to adequately care for both curing and other requirements or other failures to comply with curing requirements shall be cause for immediate suspension of concreting operations.
3. Moist curing shall be accomplished by covering of burlap, cotton mats or other approved fabric mat, used singly or in combination. Curing mats shall be thoroughly wet when applied and kept continuously wet and in intimate contact with the pavement surface for the duration of the moist-curing period. Other fabric mats shall conform in design and shall provide a curing medium at least equal to cotton mats. Cotton mats, other fabric mats and burlap strips shall be furnished in the widths or lengths, after shrinkage, required to cover the entire width and edges of the pavement lane. Mats or burlap shall be lapped at joints between adjacent sheets to prevent drying of this location. Moist-curing, when used as initial curing, shall be continued for not less than twenty four (24) hours.
4. The surface of the concrete shall be wetted with a fine spray of water and then covered with the waterproof paper. The paper shall be in pieces large enough to cover the entire width and edges of the slab and shall be lapped not less than twelve inches (12"). Paper shall be adequately weighted to prevent displacement or billowing due to wind. Paper folded down over the side of the pavement edges shall be secured by continuous bank of earth. Tears or holes appearing in the paper during the curing period shall be immediately repaired. Waterproof paper for curing concrete shall conform to the current ASTM or AASHO Specification for Waterproof Paper for Curing Concrete (C-171 and M-139, respectively).
5. White polyethylene sheeting shall consist of a single sheet having a thickness of not less than four (4) mills (0.004"). Moisture retention shall conform to the requirements of ASTM Specifications - Designation C156; except, that air-entraining Portland cement shall be used in the mortar. The material shall be tested for tensile strength and elongation as prescribed in the current ASTM Specifications Designation D-882-Method A.
6. Membrane curing compounds shall be the white pigmented type or approved equal and conform to the requirements for the current AASHO Standard Specifications for Liquid Membrane-Forming Compounds for Curing Concrete (designation: M-148). The curing compound must be applied to cover the surface completely and uniformly at a rate which will achieve the performance requirements specified in AASHO Specifications M-148. This method of curing shall be applied immediately behind the final finishing operation or after the initial curing when a combination of methods are used. Failure to provide complete and uniform coverage at the required rate will be cause for discontinuance of this method of curing and the substitution of one of the other approved methods. The compound shall be kept agitated to prevent the pigment from settling. Special care shall be taken to apply the curing compound to the pavement edges immediately after the forms have been removed.
L. Barricades and Lights: Sidewalks shall be properly barricaded and lighted after finishing.
M. Space Adjacent to Sidewalks: After removal of forms, the space alongside the sidewalk shall be filled with topsoil and leveled to prevent a finished appearance.
N. Longitudinal and Transverse Joints: Longitudinal and transverse joints shall be constructed as shown on the plans. (Ord. 0-23-79, 11-20-79)
Notes
| 1 | 1. See also subsection 11-4A-1C of this Code. |