LINE B-2-3 AND B-2-4 - Laserfiche WebLink

15-10 15-11 Curing: The contractor shall be responsible for proper curing of the concrete and backfilling the trench to an even grade. Curing shall be performed in such a manner as to prevent the premature drying of the concrete. The contractor shall use one of the methods described as follows in Subsection a), b), c) or d). a) A 3-inch layer of moist loose soil or sand shall be carefully placed over the top of the pipe immediately after the pipe is cast. The backfill shall be materially free of clods or rocks having a diameter greater than 2 inches, roots, or other deleterious foreign material. The backfill shall be carefully placed over the top of the pipe to prevent injury to the wet concrete. The thickness of the backfill shall be increased to 6 inches after initial set of the concrete has occured. The backfill shall be kept moist at all times until the pipe has been covered to a depth of 12 inches or more. Final backfill, and compaction where required, shall not be started until the pipe has developed sufficient strength to support the loads to be imposed and shall conform to local requirements and to project specifications. b) The exposed top portion of the pipe may be covered with wet burlap or other material of high moisture retentive properties immediately after the pipe is cast. The covering material shall be kept continuously moist until the placement of final backfill as described under Subsection a). Moisture retentive material may be removed or left in place at the option of the contractor. c) A pigmented membrane-curing compound conforming to the "Specifications for Liquid Membrane-Forming Compounds for Curing Concrete" (ASTM C 309) may be applied to the exposed top surface immediately after the pipe is cast. The compound shall be applied at the rate of not less than I gallon for each 150 sq. ft. of exposed concrete. The pipe shall then be covered with a maximum of 3 inches of moist loose soil when the curing compound is sufficiently hard to resist damage from the fill. Final backfill shall be placed as soon as the pipe attains suitable strength. d) Polyethylene film complying with ASTM C 171 may be placed on the exposed top surface of the pipe immediately after the pipe is cast. The film shall immediately be anchored in place with loose soil to assure continuous, adequate curing. When the concrete has set sufficiently hard to resist damage from fill, the pipe shall be covered with a minimum of 3 inches of moist lbose soil. The trench shall be completely backfilled as soon as the pipe attains suitable strength. Humidity: A humid atmoshere within the pipe as evidenced by condensa- tion on the interior surface shall be maintained for at least seven days following placement except for maximum period of 48 hours allowed for removing forms and making repairs. To prevent air drafts which may dry the pipe and to maintain a humid atmosphere inside the pipe, all openings into the pipeline shall be kept closed or covered except when and where work is actually in progress on the inside of the pipe. If necessary to promote high humidity, the pipeline shall be partially filled with ponded water during the curing period. CDS.1.14 15-4