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<br />002418 <br /> <br />Durango Pumoing Plant - Stage I <br /> <br />3. <br /> <br />Locate each batch weight indicator and volumetric dispenser in full view of the <br />operator. <br /> <br />Interlock batching controls so that a new batch cannot be started until the <br />weighing hoppers have been completely emptied of the last batch and the scales <br />register zero weight. <br /> <br />4. <br /> <br />C. Controlling Delivery of Material <br /> <br />I. Provide equipment capable of controlling the delivery of material so that the <br />combined inaccuracies in feeding and measuring during normal operation will not <br />exceed the following limits, by individual weight: <br /> <br />a. Plus or minus 1 percent for water; <br /> <br />b. Plus or minus 1-1/2 percent for cement and for cementitious materials. <br /> <br />c. Plus or minus 2 percent for sand, I-inch nominal maximum-size <br />aggregate, and 2-inch nominal maximum-size aggregate. <br /> <br />d. Plus or minus 3 percent for admixtures. <br /> <br />2. Construct the weighing hoppers to permit removal of materials batched in excess <br />of the prescribed mix design and the above tolerances. <br /> <br />D. <br /> <br />Measuring Devices for Air-entraining and Chemical Admixtures <br /> <br />1. Provide measuring devices having sufficient capacity to measure at one time the <br />full quantity of the properly diluted solution required for each batch, and maintain <br />in a clean and freely operating condition. <br /> <br />2. If admixtures are measured by a method other than direct weighing, design <br />equipment for confirmation of the accuracy of each batch quantity by use of <br />visual-mechanical gauges readily visible from the batch plant operator's station. <br /> <br />3. Construct admixture batching equipment so that the required batch quantity can <br />only be added once to each batch, and so that each admixture is discharged <br />separately into the batched mixing water as it is being discharged into the mixer. <br /> <br />E. Conveying Equipment: Construct, maintain, and operate equipment for conveying <br />batched materials from weighing hoppers into the mixer to prevent spillage of the <br />batched materials and overlap of batches. <br /> <br />F. Cement Handling Equipment: Construct and operate equipment for handling <br />cementitious materials in the batching plant to prevent noticeable dust during the <br />measuring and discharging of each batch of material. <br /> <br />G. Aggregate Batch Bins <br /> <br />I. Construct aggregate batch bins to be self-cleaning during drawdown. <br /> <br />2. Deposit coarse aggregate in the batch bins directly over the discharge gates. <br /> <br />3. Deposit aggregate larger than 3/4-inch nominal size in the batch bins through <br />effective rock ladders, unless the Contractor can demonstrate that the aggregate <br /> <br />Cast-in-Place Concrete <br />03300 - 14 <br /> <br />I <br />! <br /> <br />( <br />