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<br />002427 <br /> <br />Durango Pumoing Plant - Stage I <br /> <br />3. Adjust concrete temperature at the batch plant to ensure that the specified <br />concrete temperature is attained at the placement. <br /> <br />4. Heat concrete ingredients as necessary, but not to a temperature higher than that <br />necessary to keep the temperature of the concrete from falling below the specified <br />minimum temperature. Do not heat cement or pozzolan. <br /> <br />5. Methods of heating concrete ingredients require approval. <br /> <br />6. Employ effective means, such as precooling of aggregates and mixing water and <br />placing at night, as necessary to maintain the temperature of the concrete below <br />the specified maximum. <br /> <br />7. The Contractor is entitled to no additional compensation for heating or cooling. <br /> <br />D. Transportation <br /> <br />I. Deposit concrete in its final position in the placement within 90 minutes after the <br />introduction of the mix water and cement into the mixer. <br /> <br />2. Time limit may be extended up to 30 additional minutes if: <br /> <br />a. Concrete slump and workability allow placement without additional water, <br />and <br /> <br />b. Concrete contains the specified entrained air content after the 90-minute <br />time limit. <br /> <br />3. Time limit may be shortened during hot weather or under conditions contributing <br />to quick stiffening of the concrete. <br /> <br />4. Transport to prevent segregation of coarse aggregate or slump loss exceeding <br />2 inches. <br /> <br />5. Deposit concrete as near as practical to its final position by using buckets, chutes, <br />conveyors, or concrete pumps. <br /> <br />a. Do not use aluminum pipe or aluminum chutes to deliver concrete. <br /> <br />b. Buckets shall be capable of promptly discharging concrete of the specified <br />mix design. <br /> <br />c. Dumping mechanism shall be capable of discharging at one location <br />repeated small portions of concrete from a full bucket. <br /> <br />d. Attach drop chutes or tremies to buckets or conveyors where the distance <br />from the point of discharge to the placing surface exceeds 10 feet. <br /> <br />e. Equip concrete pumps with slicklines having a minimum diameter of 5 <br />inches and capable of transporting concrete containing a maximum <br />amount of coarse aggregate and a minimum amount of sand, cement, and <br />water. The minimum proportion of 1- to 2- inch aggregate shall be 4 cubic <br />feet ( solid volume) per cubic yard of concrete and, dependent upon the <br />shape and texture of the aggregate utilized, this proportion will be <br />increased as practical. <br /> <br />Cast-in-Place Concrete <br />03300 - 23 <br />