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immediately after the first concrete has been deposited in the <br /> forms. <br /> 10.6 DEPOSITING IN COLD WEATHER <br /> The Contractor shall provide adequate equipment for heating materials and <br /> protecting the concrete during freezing or near freezing weather. Said <br /> equipment shall be available at all times and shall be used for the period <br /> specified in this specification. All work during cold weather shall be <br /> executed in accordance with ACI 306. <br /> 10.7 DEPOSITING IN HOT WEATHER <br /> When concrete must be placed during hot weather, the Contractor shall <br /> follow the procedures outlined in ACI 305. <br /> 10.8 METHODS FOR BONDING JOINTS, TOPPING, OR PATCHING HARDENED <br /> CONCRETE <br /> 10.8.1 Concrete on which other concrete is to be placed shall be either <br /> plastic or thoroughly hardened, but not in a semihardened state <br /> that may be disrupted and weakened by the added load and the <br /> jarring of placement. <br /> 10.8.2 To provide bond between successive lifts of concrete, the <br /> exposed surface shall be cleaned and roughened without loosening <br /> the embedded aggregate. Brooms or air-water jets shall be used <br /> after the start of initial setting of the concrete. Sand-blasting or <br /> air-tooling shall be employed after the concrete has hardened. In <br /> all cases, the surface film and laitance, or diluted paste, shall be <br /> removed and a reasonably high percentage of aggregate exposed. <br /> Immediately before the new concrete is placed, the old surface <br /> shall be clean, damp, and free from standing pools of water. <br /> 10.8.3 Batches of neat cement or of mortar having about the same <br /> proportion of cement to sand as used in the concrete shall be <br /> deposited and well brushed in just ahead of the new concrete. <br /> SPEC. B- CONCRETE <br /> PAGE 16 <br />