314 FLOWABLE BACKFILL

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314.01 DESCRIPTION
Furnish, haul, and place flowable cement stabilized backfill material. When specified, use for utility cut backfill, pipe backfill, or for filling abandoned pipes.
314.02 MATERIALS
Controlled Low Strength Material       902.16
314.02.01 Fillers. When required, fillers shall be natural aggregates with a maximum size of 3/4 in. and may include sands. Bottom ash shall not be used as filler.
314.02.02 Components. Toxic and deleterious components shall not be used in the backfill mixture. The mixture shall have a 28 day, unconfined compressive strength of at least 100 psi based on the manufacturer's certification. Certification shall include the actual test data for each mixture to be used.
314.02.03 Analysis. Chemical analysis of the fly ash used in the mixture shall conform to U.S. EPA EP Toxicity Standards. Whenever the coal source is changed or replenished, and when fly ash from a different source is used, conduct an analysis of the fly ash from each stockpile. Submit the results of the analysis to the Engineer for approval prior to using the mixture.
314.03 CONSTRUCTION
Place the material according to the manufacturer’s recommendations or as directed by the Engineer. Backfill utility trenches full depth to the top of the subgrade. Fill all voids during the backfill operation.
Protect the backfilled utility cut from freezing and traffic for 24 hours. Wait at least 24 hours after backfilling is complete and approved by the Engineer before beginning the paving operations.
Fill abandoned pipes with backfill after each end of the pipe has been adequately plugged. Refer to 303.03.06. Cut two holes into the plug at the upstream end and pump backfill into the pipe through one of the holes until the pipe is completely filled.
Keep and submit detailed records of all flowable backfill placed. Include the source of the fly ash, the date placed, the location, depth, and the quantity used.
314.04 MEASUREMENT AND PAYMENT
Flowable Backfill will be measured and paid for at the Contract unit price per cubic yard. The payment will be full compensation for all material, labor, equipment, tools, and incidentals necessary to complete the work.