Eisenhower_South_Culvert_Recess_Concrete_Rehabilitation_Scope_of_Work_-_Draft_2016.12.22.pdf

Saint Lawrence Seaway Development Corporation Eisenhower South Culvert Recess Concrete Rehabilitation Scope of Work – Draft December 22, 2016

Scope of Work:

The Contractor shall provide all labor, equipment and materials required to complete this scope of work. All work shall be performed in accordance with American Concrete Institute (ACI) Specification for Shotcrete 506.2 and to industry standards.

The Corporation estimates 100 cubic yards of concrete rehabilitation will be required, but the final volume may differ. The Contractor will be paid for actual work completed. The Corporation will complete the required preparation work for concrete rehabilitation. The Contractor will be authorized to commence work on or about February 13, 2017 and shall complete work no later than March 3, 2017. Under no circumstances shall the contractor be authorized to work within the culvert recess or have materials, tools or equipment within the culvert recess after March 3, 2017.

The Contractor shall provide means for heating as necessary. Additionally, partitions and/or vapor barriers shall be erected to isolate heating areas by the Contractor. The Contractor shall be responsible for a safe work environment at all times. The Contractor shall submit a safety plan for approval prior to commencing work.

Requirements for Shotcrete Application:

This Scope of Work is for the application of concrete, also referred to as shotcrete, which is pneumatically projected at high velocity in accordance with the “dry” placement method where all ingredients are pneumatically conveyed dry to the nozzle for final mixing with water before projection onto the work surface. Shotcrete shall be QUICKRETE Shotcrete MS or approved equal. The shotcrete dry mix may be supplied as a prepackaged single component dry product ready for field application. Mixing and application shall be performed in accordance with American Concrete Institute (ACI) Specification for Shotcrete 506.2. Portions of this specification with other special requirements are presented in this section.

1. Submittals: Submit the manufacturer’s product data and installation instructions for each material and ingredient used. Submit the mix design with proportions of all ingredients.

Include the manufacturer’s Safety Data Sheets as appropriate.

2. Quality Assurance: The manufacturer of single-component dry mix product shall be a company with at least fifteen years of experience in the manufacturer and marketing of pre-packaged cementitious repair materials. The contractor shall be experienced and qualified to perform the work and nozzlemen shall be certified in accordance with requirements of ACI CP-60 Craftsman Work Book and the ACI 660 Shotcrete Nozzlemen Certification Committee. A test panel of at least 2 feet square by 8-inches deep shall be prepared by the contractor at the site for each day of shotcrete placement.

The test panels shall be cored by the Contractor and/or its approved laboratory for visual examination for bond and consolidation and compressive strength determination.

Pursuant to the test panel findings, the completed work may also be cored by the Corporation for evaluation of the in-place bond, consolidation and compressive strength.

3. Delivery, Storage and Handling: Deliver prepackaged shotcrete materials and cements in original packaging, labeled with product identification, manufacturer, batch number and shelf life. Store all ingredients in a dry area. Keep ingredients dry and protected

Scope of Work – Draft from the weather, direct sunlight and freezing. Handle packaged materials in accordance with manufacturer’s printed recommendations.

4. Materials: The shotcrete is a microsilica-fortified, air-entrained cement-based mixture of

Portland cement, microsilica, air entrainment, pozzolans and graded aggregates. Coarse aggregates shall be no larger than 3/8-inch (0.375”) in size. The shotcrete shall comply with ASTM C 1480 Type FA. Grades GU, SR, LP. Water-cement ratio of the completed mix shall be no greater than 0.40. The 28-day compressive strength shall be at least 5,000 pounds per square inch (psi) as tested by an approved laboratory. Air content shall be 6 to 9 %. To reduce dust, predampen pre-packaged shotcrete materials before they are conveyed to the nozzle. Instructions provided by the manufacturer regarding mixing and handling shall be followed. Use only potable water in shotcrete.

5. Surface Preparation: The repair area shall be dewatered as necessary to allow unobstructed dry access to all surfaces. Additionally, repair area shall be dust/debris free and dampened prior to shotcrete placement. The Corporation will perform all other preparation to include squaring off repair areas, saw-cutting to sound concrete and installation of reinforcing mesh and bars. Do not use bonding agents.

6. Grade and Alignment: The proper surface grade and alignment of the completed shotcrete shall be maintained by use of taut “ground” wires that are set to the original profile of the concrete base. The shotcrete can then be carried to the ground wires. A sufficient number of wires shall be used to insure a square and even conformity to the original dimensions of the concrete base. Ground wires shall also be set at corners to insure that the reconstructed corner conforms to the original geometry and dimensions.

7. Application: Place shotcrete first into corners, recesses and other areas where rebound or overspray cannot escape easily. Hold the nozzle perpendicular to the receiving surface and move it in circles to improve consolidation and reduce rebound (separated aggregate that bounces or ricochets out of the placement). In corners, direct the nozzle at a 45-degree angle, or bisect the corner angle if different than 90 degrees. Rebound shall not be incorporated in the completed work. Apply the shotcrete in such a manner as to prevent sags and sloughing. Apply around reinforcing materials to completely encase it and have a free flow of material completely around the reinforcement so there are no voids. The front face of reinforcement shall remain clean during the encasement. Shotcrete shall not be deposited into standing or running water.

8. Weather Conditions: Shotcrete application shall not be done in windy conditions that cause separation of the mix. The prevailing ambient temperature shall be maintained at least 50 degrees Fahrenheit. Surfaces against which shotcrete is applied shall not be below 32 degrees Fahrenheit, and shall be free of frost. In the event the lower ambient and/or surface temperatures/conditions cannot be achieved, the Contractor shall provide means for suitable heat application. Shotcrete materials shall be no less than 50 degrees Fahrenheit or more than 100 degrees Fahrenheit, and surfaces against which shotcrete is applied shall be no greater than 100 degrees Fahrenheit.

Scope of Work – Draft

9. Finishing and Curing: Finish immediately after shotcrete application with a steel trowel to a smooth surface, with care to prevent loosening of the bond. Shotcrete application areas shall be cured at least 3-days in accordance with Cast-in-Place concrete industry standards and, at a minimum, be maintained at an ambient temperature of 50 degrees Fahrenheit or greater.