Where concrete sidewalk, curb and gutter, or combined sidewalk, curb and gutter is
constructed on a street or avenue that has been gravelled, the Contractor, at no cost to The City, shall blade the gravel to within the middle 3.6 m of the roadway. On completion, this material shall be replaced to the satisfaction of The City.
311.03.00 – Base Preparation
311.03.01 – Earth Sub-grade and Base Gravel Fill
The sub-grade shall be true to cross-section and grade. Irregularities in the sub-grade may be adjusted by use of compacted crushed gravel. Prior to the placing of concrete, the sub- grade shall be compacted to a uniform density of not less than 97.0 percent of design density.
When it is necessary to bring the base to proper elevation by the use of gravel, the Contractor shall supply approved gravel and provide all material and labour necessary to load, haul, and place it on the finished sub-grade. Placing and compaction of gravel shall be carried out in accordance with section 305.00.00 – Gravel Road and Lane Construction.
311.00.00 CONCRETE SIDEWALK, CURB AND GUTTER
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Where concrete sidewalks are placed on a fill, a shoulder of one metre width (measured from the edge of the sidewalk) shall be constructed. The fill shall be constructed with 3:1 side slopes.
The Contractor shall place and compact a 50 mm lift of 25 mm crushed gravel prior to placing concrete for islands or medians. In areas, where island and median concrete is placed above asphalt, the entire volume between the asphalt and the concrete shall be filled with compacted 25 mm crushed gravel. The supply, placing, and compacting of this gravel shall be deemed incidental to the Unit Rates for Sidewalks or Median and Island Concrete. If, in the opinion of the Engineer, there is a danger of excessive absorption of concrete water by the earth or gravel base, the Contractor shall adequately sprinkle the base with water.
311.03.02 – Replacement of Unsuitable Material
Where unsuitable material is encountered during excavation, the Contractor shall notify the Engineer and, if directed, shall excavate the unsuitable material and backfill the area with an approved fill, in accordance with section 302.00.00 – Earthwork. The Contractor shall be responsible for the replacement, at his own expense, of any failure of the work which, in the opinion of the Engineer, was caused by an unstable base.
311.04.00 – Forms
311.04.01 – Formwork
Forms for sidewalk, curb and gutter, combined sidewalk curb and gutter, aprons, invert crossings, and catch basins shall be of metal or timber properly seasoned and free from warps or other defects. Metal forms shall be of approved type and section. The face of curb form shall be removable without disturbing back and gutter forms. Forms shall be smooth and clean on the surface(s) next to the concrete and be oiled with an approved lubricant. Forms shall be rigidly held true to the established lines and grades. No concrete shall be deposited against forms until the forms and their placing has been approved by the Engineer.
311.04.02 – Stripping of Forms
Face of curb forms are to be removed after the initial set. Adequate care shall be taken in removing forms to avoid spoiling or marring the concrete. Such patching as may be necessary shall be started immediately after removal of the forms.
311.00.00 CONCRETE SIDEWALK, CURB AND GUTTER
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Immediately after form removal and/or patching, the exposed surfaces shall be sprayed with a curing membrane.
311.05.00 – Reinforcing
1) General
Where required by the Engineer, structures shall be reinforced in accordance with the drawings provided.
Cold drawn steel wire shall meet the requirements of ASTM designation A 82.
Wire mesh shall meet the requirements of ASTM designation A 185. Overlapping of wire mesh reinforcing shall be a minimum of 300 mm and be wired together.
Bar reinforcing shall meet ASTM Designation A 184 and ASTM Designation A 304
intermediate grade new billet deformed steel. Overlapping of bar reinforcing shall be 30 bar diameters and be wired together.
The mesh and/or bar reinforcing shall be supported above the compacted gravel base to ensure a minimum 50 mm cover of concrete. The manner of supporting the reinforcing shall be approved by the Engineer. Concrete with wire mesh position at the bottom of the
concrete element shall be deemed unacceptable.
2) Wire Mesh
A single layer of 150 mm by 150 mm No. 10 by 10 gauge wire mesh shall be installed in private residential driveway crossings and commercial sidewalks.
A double layer of 150 mm by 150 mm, No. 10 by 10 gauge wire mesh shall be installed in public lanes and commercial driveway crossings.
The mesh shall extend the full width of the crossing. In aprons, the mesh shall extend to the full width, special attention being made that the mesh extends into the corners of the apron. All acute angle apron corners shall be constructed and reinforced as shown in the Standard Drawing 454.1013.004.
Reinforcing mesh shall be rolled or otherwise straightened to make a perfectly flat surface before placing.