706Concrete Walks, Drives, and Incidental Paving

706.01 DESCRIPTION. Furnish and construct portland cement concrete

walks, handicapped curb ramps, drives and incidental paving slabs in accordance with these specifications and in conformity with lines, grades, and dimensions shown on the plans or established.

706.02 MATERIALS. Materials shall comply with the following

sections or subsections: Portland Cement Concrete (Class M) Section 901 Joint Filler 1005.01.3 Reinforcing Steel 1009.01 Curing Materials 1011.01

706.03 Construction Requirements.

706.03.1 Excavation: Excavate to required depth and width. Shape

the top of the subgrade and compact to a firm, even surface conforming to the section shown on the plans. Remove unsuitable material and dispose of in accordance with 202.02 and replace with approved material at no direct pay.

706.03.2 Forms: Forms shall be of wood or metal and shall extend

the full depth of concrete. Forms shall be straight, clean, and of sufficient strength to resist the pressure of concrete. Brace forms to ensure that forms remain in horizontal and vertical alignment until their removal. Concrete may be placed by slip-form methods. Place slip-formed concrete with an approved machine designed to spread, vibrate, consolidate, and finish concrete in one pass of the machine with a minimum of hand finishing. Rigidly hold sliding forms together to prevent spreading of forms. After the passing of the side forms, there shall be no noticeable slumping of concrete.

706.03.3 Subgrade: Thoroughly moisten the subgrade immediately

prior to placing concrete.

706.03.4 Placing and Finishing: Place the concrete on the

subgrade, strike-off to required thickness, and tamp sufficiently to bring the mortar to the surface. Finish the surface with a wood float or steel trowel followed by brushing to a slightly rough finish. Round joints and edges with an edging tool having a 1/4 inch radius.

706.03.5 Joints:

706.03.5 1 Expansion Joints: Fill expansion joints with 1/2

inch thick preformed expansion joint filler. Install expansion joints at maximum 100-foot intervals, and between intersecting paving and any fixed structure, such as a building, bridge, or curbing, and between intersecting paving and the handicapped curb ramps. Extend expansion joint material for the full width and depth of paving.

706.03.5 2 Weakened Plane: Form weakened planes by a

jointing tool or other acceptable means. Extend weakened planes into concrete for at least one-quarter of the depth. Weakened planes shall be approximately 1/8 inch wide.

706.03.5 2.1 Walks: Space weakened planes for walks equal

to the width of the walk.

706.03.5 2.2 Drives: Form a longitudinal weakened plane

along the centerline of drives more than 16 feet wide. Form transverse weakened planes at not more than 16-foot intervals.

706.03.5 2.3 Incidental Paving: Form weakened planes for

incidental paving at intervals not exceeding 30 times the thickness of the concrete in length or width. Construct joints in incidental paving placed adjacent to jointed concrete to match existing joints, with intermediate joints formed as necessary not to exceed the maximum joint spacing.

706.03.5 3 Construction Joints: Form construction joints

around manholes, utility poles, etc., extending into paving. Install 1/4 inch thick preformed expansion joint filler into these joints.

706.03.5 4 Tie-ins: Make tie-ins of existing concrete by full

depth sawing at no direct pay.

706.03.6 Curing: Cure concrete in accordance with 601.03.10.

706.03.7 Detectable Warning Surface for Handicap Ramps

and At-Grade Sidewalk Intersections: When sidewalks intersect with roadways, equip the sidewalk with a detectable warning system consisting of raised truncated domes as a transition between the sidewalk and the street as required by the Americans With Disabilities Act, 28 CFR § Part 36, ADA Standards for Accessible Design. Install detectable warnings (truncated domes) on the ramp surface over the full width of the ramp throat for a distance of 24 inches in the direction of travel from the back of the curb. Also install detectable warnings (truncated domes) on at- grade sidewalks intersecting with roadways for a distance of 36 inches in the direction of travel from the end of the sidewalk. Detectable warning surfaces may be added to at-grade sidewalks intersecting with driveways at the discretion of the design section or Project Engineer. Lay out truncated domes on a square grid in order to allow enough space for wheelchairs to roll between the domes. Light reflectance of the truncated domes and the underlying surface shall meet the 70 percent contrast requirement of ADAAG.

706.04 MEASUREMENT. Quantities of concrete walks, drives, and

incidental paving slabs for payment will be the design quantities as specified on the plans and adjustments thereto. Design quantities will be adjusted if the engineer makes changes to adjust to field conditions, if design errors are proven or if design changes are made. Design areas are based on the horizontal dimensions shown on the plans. Excavation, backfill, reinforcing steel, and joint materials will not be measured for payment. Handicapped curb ramps, including the detectable surface warning system, will be measured per each. Detectable surface warning systems for at-grade sidewalk intersection will not be measured for payment.

706.05 PAYMENT. Payment for concrete walks, drives, and incidental

paving will be made on a lot basis at the contract unit price per square yard, adjusted in accordance with the following provisions. Payment for each lot will be made in accordance with table 901-5. Size, sampling, and testing of each concrete lot shall be in accordance with the materials sampling manual. Payment for handicapped curb ramps, including the detectable surface warning system, will be made at the contract unit price per each and shall include, but not be limited to, curb transitions, detectable warning system, gutter, landing, and base. Payment will be made under: Item No. Pay Item Pay Unit 706-01 Concrete Walk Square Yard 706-02 Concrete Drive Square Yard 706-03 Incidental Concrete Paving Square Yard 706-04 Handicapped Curb Ramps Each