Specifications include, but are not limited to: A. HPC-O concrete for bridge deck overlay shall include fiber reinforcement as called for in the contract documents. Use approved products and proportions of synthetic micro and macro fiber, and incorporate into the concrete mix in accordance with these Special Provisions. The purpose of the fiber reinforcement is to mitigate risk and effects of cracking and improve the durability of the concrete. B. Apply Section 2413 and Division 41 of the Standard Specifications, with the following modifications. 230002.02 MATERIALS. A. Fiber. 1. General. Fiber reinforcement shall consist of micro and macro fibers. Micro and macro fibers may be supplied as separate products to be proportioned and blended with the mix at the time of concrete production, or may be supplied as a pre-combined, pre-packaged blended fiber product. 2. Microfiber. For microfiber supplied as a separate product: a. Use approved microsynthetic-fibrillated concrete fibers in accordance with Materials I.M. 491.27 Appendix A. b. Dose microfiber at a minimum rate of 1 pound per cubic yard of concrete. 3. Macro Fiber. For macro fiber supplied as a separate product: a. Use approved macrosynthetic concrete fibers in accordance with Materials I.M. 491.27 Appendix B. b. Dose macro fiber at a minimum rate of 4 pounds per cubic yard of concrete. 4. Pre-Combined Micro / Macro Fiber Blend. For microfiber and macro fiber supplied as a pre-combined, pre-packaged product: a. Use approved macrosynthetic blend concrete fibers in accordance with Materials I.M. 491.27 Appendix B. b. The blend ratio by weight of microfiber to macro fiber in the pre-combined product shall be 20% microfiber to 80% macro fiber, +/- 5%, unless otherwise approved in writing by the Engineer. c. When pre-combined micro / macro fiber blends are used, the entire dosage of fiber shall be made using a single blended product. Do not mix blended fiber products with other blended or non-blended fiber products. d. Dose pre-combined micro / macro fiber blend at a minimum rate of 5 pounds per cubic yard of concrete. B. Concrete. 1. General. Select a mix which satisfies all applicable requirements and achieves appropriate workability upon incorporation of fibers at the required dosage rate. 2. Bridge Deck Overlays. a. Use Class HPC-O concrete mix in accordance with Article 2413.02, D, 2 of the Standard Specifications. b. Place concrete with slump as specified in Article 2413.02, D, 2, a. When mid-range water reducer is used, target slump may be increased to 5 inches, allowing a maximum of 6 inches as a tolerance. Commence testing for concrete slump within 0 to 4 minutes after the concrete is discharged.
