Execution 3.01 Installation

A. Concrete paving and walks shall be constructed in accordance with the following provisions:

1. Slopes: The Contractor shall construct all paving in accordance with the spot elevations, details, and cross-sections. This shall include the cross-slopes, expansion joints, construction joints, and finish. In addition, the following shall apply to the construction of paving where not otherwise covered by details;

provide grade stakes not more than 25 feet apart for all walk construction;

check top of forms for grade before placing concrete; introduce short vertical curves in walks as shown on the Drawings or at points where change in walk grade exceeds two percent. For a distance of two feet from top to bottom of steps, the walk slope shall not exceed 1/2-inch per foot. Provide maximum 1/4-inch per foot crown or cross-slope in the direction indicated on the Drawings. Pitch walks to make slight adjustments in slope at walk intersections as necessary or directed to provide proper drainage.

2. Dimensions: Concrete paving shall be of one-course construction of the thickness and width shown on the Drawings.

Portland Cement Concrete Paving 32 1313 - 6 3. Expansion Joints: Provide expansion joints, not more than 30 feet apart, at

walk junctions and intersections, at top and bottom of steps, and where walks abut curb returns, buildings, platforms, or other fixed structures, or terminate at curbs. Locate expansion joints at such points where concrete panels are not larger than 250 square feet. At walk junctions and intersections, the required expansion joints shall be located at the end of each rounding or fillet.

Expansion joints shall be at right angles to the slab and extend to within 1/4-inch of the surface.

4. Isolation Joints: Isolation joints shall be used to isolate fixed objects abutting or within the paved area. They shall contain premolded joint filler as shown on the Drawings and shall be sealed at the top, all in a manner similar to that specified for expansion joints.

5. Control or Contraction Joints: Control or contraction joints shall be formed by one of the following methods as indicated on the Drawings; sawing, forming by hand, or forming by premolded filler. Joint depth shall be a minimum of one-fourth of the slab thickness. Hand formed joints shall have a maximum edge of 1/4-inch. Sawing of joints shall be as soon as the concrete has hardened sufficiently to permit sawing without excessive raveling. All joints shall be completed before uncontrolled shrinkage cracking occurs. Joints shall be continuous across the slab, unless interrupted by full-depth premolded joint filler.

6. “Picture-framing” will not be permitted unless specifically indicated on the Drawings.

B. Placement

1. Before placing concrete, free-standing water, snow, ice, or other foreign materials shall be removed from the subgrade or aggregate base.

2. All forms shall be thoroughly cleaned, secured in position, and coated with a form release agent.

3. If metal keyway is used to form a specified joint, it shall be clean, secure in position to ensure a straight joint and proper depth, and coated with a form release agent. The metal keyway is to be removed prior to pouring adjacent grids.

4. Concrete shall be placed, struck off, consolidated, and finished to plan grade with a mechanical finishing machine, vibrating screed, or by hand-finishing methods when approved. In lieu of fixed forms, the Contractor may place concrete with a slipform paver designed to spread, consolidate, screed, and float finish the freshly placed concrete in one complete pass of the machine.

Pavement is to be pitched to area drains or perimeter areas to remove water and shall conform to finished grades as established on the plans.

Portland Cement Concrete Paving 32 1313 - 7 C. Finishing

1. Contractor shall review all concrete finish locations with the Owner’s representative prior to commencement. Each type of finish shall be indicated in a 3’ x 3’ sample area for Owner’s Representative review and approval.

Approval of subsequent finishing shall match the approved sample.

a. Smooth Trowel Finish (beneath all roof lines of architectural structures):

Tamp and screed the concrete true to grade and section, bringing sufficient mortar to the surface for finishing and give a smooth trowel finish. Round all edges, including those along expansion joints and grooves, to a 1/4-inch radius. Where a pavement changes at an adjacent concrete paving, provide a 1/4” beveled trowel joint.

b. Broom Textured Finish (all surfaces not beneath an architectural structure or roof over-hang where the grade is 1 1/2% to 5%): Tamp and screed the concrete true to grade and section, bringing sufficient mortar to the surface for finishing and give a wood or carpet-float finish provided that where the walk grade exceeds five percent, the surface shall be given a bolted or broomed finish as directed by the Owner’s Representative.

Round all edges, including those along expansion joints and grooves, to a inch radius. Where a walk terminates at a curb, finish the walk 1/4-inch above the curb, providing a neat bevel.

c. Rough Broom Textured Finish (all surfaces greater than 5% to 13%):

Tamp and screed the concrete true to grade and section, bringing sufficient mortar to the surface for finishing and give a wood or carpet-float finish. The surface shall be given a rough broom finish as directed by the Owner’s Representative. Finish shall have twice the roughness of a regular broom finish. Round all edges, including those along expansion joints and grooves, to a 1/4-inch radius.

D. Curing

1. Concrete shall be cured by protecting it from loss of moisture, rapid temperature change, and mechanical injury for at least three days after placement. After all free water has disappeared from the surface, a liquid membrane-forming compound or other approved curing material shall be uniformly sprayed on all exposed surfaces. The rate of application shall be in accordance with the manufacturer’s recommendations.

2. When concrete is being placed in cold weather and the temperature may drop below 35° F, straw or hay insulated curing blankets or other suitable materials shall be provided to prevent freezing of concrete. Concrete damaged by freezing or other weather action shall be removed and replaced at the Contractor’s expense.

E. Protection: Remove no forms for 24 hours after pouring concrete. Protect concrete walks from pedestrian traffic for a period of three days after pouring.

Portland Cement Concrete Paving 32 1313 - 8

3.02 Plasticized Concrete

A. If the Contractor requests a slump in excess of the above specified, it shall be obtained by addition of an approved plasticizer, rather than water, and shall conform to ASTM C 494, Type F (Mighty 150 or FX 326).

B. The Owner’s Representative shall approve the admixture and content prior to use by the Contractor. The Contractor shall also test admixtures in combination with job cements under conditions to be expected on the job site prior to their actual incorporation into any full-scale field project.

C. If plasticized concrete is used, melamine-based high range water reducers shall be utilized; control slump shall be 3-inches; air entrainment shall be 6 percent ± 1 percent; the water-cement ratio shall be 0.47; and the compressive water reducer shall be 0.3 percent to 0.4 percent by weight of cement.

3.03 Existing Roads, Walks, and Curbs

A. Cut, patch, and replace existing roads, walks, and curbs as required for new construction.

B. Repair or replace existing surfacing damaged by construction activities. All such work is to match existing.

C. Meet all requirements as may be established by local governing agencies.

3.04 Cleanup

Upon completion of the work, Contractor will remove all equipment, tools, rubbish, excess materials, or other debris from the site and all parts of the work shall be left in a clean and finished condition acceptable to the Owner.

END OF SECTION

Walkways 32 1623 - 1 Section 32 1623

Walkways

Part 1 General