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1 <br />' DIVISION 3 <br />CONCRETE <br />03300 - CAST -IN -PLACE CONCRETE <br />j <br />B. <br />Tampering and Control of Mixing Water: Mix concrete only in quantities <br />for placing. Water be <br />may added only if neither maximum sible <br />water -cement ratio nor maximum slump is exceeded. Incorporate <br />ratewater by <br />additional mixing equal to at least half of total mixing required. <br />Accomplish addition <br />of water above that permitted by limitation on water - <br />cement ratio by adding a quantity of cement sufficient to maintain <br />proper <br />water -cement ratio. Such addition shall be authorized by Architect/ <br />Engineer. <br />C. <br />Weather Conditions: Protect concrete from physical damage or reduced <br />strength due to weather extremes. In cold weather comply with ACI 306; in <br />hot weather comply with ACI 305. <br />8. <br />PLACING OF CONCRETE <br />A. <br />Preparation before placing: <br />1. Remove hardened concrete and foreign materials from inner surfaces of <br />conveying equipment. <br />2. Complete formwork, remove snow, ice and water, secure reinforcement in <br />place, position expansion joint material, anchors, and other embedded <br />items and have entire preparation approved. <br />3. Sprinkle semiporous subgrades to eliminate suction and seal porous <br />subgrades in an approved manner. <br />4. -Do not place concrete on frozen ground. <br />B. <br />Conveying: <br />9 <br />i <br />1 <br />1 <br />1 <br />1 <br />1 <br />5264 <br />1. Handle concrete from mixer to place of final deposit as rapidly as <br />practical by methods which will prevent segregation or loss of <br />ingredients and in a manner which will assure that required quality of <br />concrete is maintained. <br />a. Use truck mixers, agitators, and nonagitating units with manner of <br />operation conforming to applicable requirements of ASTM C-94. <br />b. Use metal or metal -lined chutes with slope not exceeding 1 <br />vertical to 2 horizontal and not less than 1 vertical to 3 <br />horizontal. Chutes more than 20' long and chutes not meeting <br />slope requirements may be used provided they discharge into a <br />hopper before distribution. <br />c. Pumping or pneumatic conveying equipment shall be of suitable kind <br />with adequate pumping capacity. Control pneumatic placement so <br />that segregation is not apparent in discharged concrete. <br />SECTION 03300 - 5 <br />