Special Provision for Colored Concrete

 

Description – This work shall consist of constructing stamped concrete streetscapes in accordance with Standard Plan R-29 (Series) and the 2003 Michigan Department of Transportation Standard

Specifications for Construction, except as modified herein.

 

Materials. The materials shall meet the following requirements:

 

Sound Earth______________________________205

Granular Materials Class II___________________902

Joint Fillers_______________________________914

 

Concrete – Concrete shall be a__________psi mix design. Submit two (2) copies of laboratory tests verifying strength requirements. The coarse aggregate shall be Michigan Series 6AA quarried limestone gradation as specified in Section 902 of the Standard Specifications for Construction.

 

All course or fine aggregate used in the concrete mixture shall be from the same MDOT approved source.

 

Concrete Admixtures. All shall meet the requirements of Section 903 Standard Specifications for Construction. Admixtures containing calcium chloride are not permitted.

 

Integral Color. Integral coloring shall be__________, manufactured by Prism Pigments, or approved equal. All integral color shall meet ASTM C979 for color steadfastness. Independent laboratory testing shall be submitted if requested.

 

Color Hardener. Dry-shake color hardener shall be__________, manufactured by Prism Pigments, or approved equal. Recommended coverage is 60 lbs./150ft².

 

Release Agent. The dry-shake powder which facilitates release of imprinting tools, shall be manufactured by Prism Pigments, or approved equal.

 

Equipment. The concrete surface shall be patterned as shown on plans. Acceptable manufacturers and styles of imprinting tools are as follows

 

Pattern:_______________.

 

Pattern Manufacturer Source:     Brickform Rafco (866) 792-9009

Proline Concrete Tools (616) 299-8897

Matcrete (989) 529-4433

 

 

Construction Methods

 

Preparation of Base. Excavation shall be made to the required depth and to a width that will permit forming. All unsuitable material shall be removed below the required depth and replaced with sound earth. The prepared base shall be compacted to 95% of its maximum unit weight in accordance with Section 205 of the Standard Specifications for Construction. Granular material base shall be placed and compacted on the sound earth, as directed by the Engineer. A vapor barrier shall not be used.

 

Forms. Forms and forming shall meet the requirements of Subsection 803.03.B of the Standard Specifications for Construction.

Stamped Mock-ups. 4′ x 4′ stamped and colored mock-ups shall be constructed from approval by the Engineer and Owner prior to construction. Mock-ups shall include

 

Concrete Coloring. The coloring pigment must be added at the batch plant. The truck mixer drum shall be rotated a minimum of 50 revolutions at mixing speed after adding the coloring pigment. The amount of coloring pigment to be added shall be as specified by the pigment manufacturer.

 

Protection of Surrounding Surfaces. All surrounding surfaces, including, but not limited to walls, store fronts, should be protected to prevent discoloration from the concrete. All clean-up and reports shall be responsibility of the contractor.

 

Placing Concrete. Concrete placement shall meet the requirements of Subsection 803.03.C of the Standard Specifications for Construction, and as described herein.

 

The surface shall be struck off and floated to produce a smooth even surface with a maximum surface variance of plus or minus 1/8 inch in 10 feet in any direction. All edges and joints shall be rounded to the specified radius with an approved finishing tool.

 

Controls shall be laid out prior to stamping the concrete with any necessary strings and stakes for lining up the stamping tools. Unless otherwise specified, ungrouted installations shall be stamped 5/16 inch. The concrete is ready to be stamped when a 2 inch deep impress made with the finger does not fill with water and the concrete maintains its shape.

 

The stamps must be clean of foreign matter prior to the stamping operation. It is generally recommended to clean stamps and reapply powdered or clear liquid release to all contact surfaces approximately every 25-30 square yards.

 

The freshly placed concrete surface shall be barricaded against access for at least 24 hours after the release powder has been applied. The concrete shall not be opened to pedestrian traffic until the release powder has been washed off.

 

Joints. The control joints shall be sawed as soon as the concrete has hardened such that no raveling or spalling occurs, but before any random uncontrolled cracking develops. Joint depths shall be maintained at ¼ of the slab(s) thickness. Layout control joints to follow stamping pattern as closely as possible.

Joints shall be sawed with their faces perpendicular to the surface of the sidewalk and shall not vary more that 3/16 inch from their designated position. Transverse joints shall be constructed at right angles to the centerline of the sidewalk and longitudinal joints parallel to the centerline. Locations for longitudinal and transverse joints shall be as directed by the Engineer. When the sidewalk is constructed adjacent to a previously placed slab, transverse joints in the succeeding slab shall be aligned with like joints in the adjacent slab.

 

Expansion joint filler shall extend to the full depth of the joint with its top surface ¼ – ½ inch below the finished surface.

 

Acid Washing. Apply a one (1) part muratic acid to 10 parts water to the surface and agitate the concrete with the side of a straw broom a minimum of 36 hours after placement. Wash surface until proper color has been achieved and then flush thoroughly. The contractor shall attempt to remove 80% or more of the color release prior to sealing.

 

Detailing. If squeeze joints are present a grinder or chisel shall be used to remove. Ground areas shall be burnished with dry release agent using a camel back sponge or 1-2″ wide brush with bristles cut down to ½”. Blow away excess release with a high velocity blower.

 

Maintaining Traffic. The concrete shall not be opened to pedestrian traffic until at least 24 hours after the sealer has been applied. During such period, entrance to all residents and businesses shall be maintained at all times. Construction should be staged to allow for such access.

 

Submit official documentation indicating that the application contractor has an ACI Certification for Flatwork Finishing and has Michigan Concrete Association (MCA) Decorative Concrete

 

Completion Certificate or equivalent Manufacturer training and certification.

 

Measurement and Payment. The completed work as measured for Stamped and Colored Concrete, _____ in will be paid for at the contract unit price for the following contract item (pay item).

Contract Item (Pay Item)Pay Unit

 

Stamped and Colored Concrete, ____ in ………………………… Square Foot

 

Stamped and Colored Concrete, ____ in will be measured in place by area in square feet. Payment for Stamped and Colored Concrete, ____ in shall include all labor, material and equipment required to perform all work in accordance with this special provision and as show on the plans, including but not limited to providing the Engineer and the City of _________ with the final documentation of the concrete mix design and a unit of each stamping tool used to complete the project.

 

The contractor is responsible for all costs associated with construction and disposal of mock-up slabs, with no additional compensation permitted.

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