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<br />0024:9 <br /> <br />Durango Pumoing Plant. Stage 1 <br /> <br />will not be subject to breakage and degradation beyond the gradation specified <br />herein, and beyond allowable limits specified in table 03300B - Allowable <br />percentages of deleterious substances in coarse aggregate. <br /> <br />H. Sampling Facilities <br /> <br />I. Provide convenient facilities to readily and safely obtain representative samples of <br />cement, admixtures, sand, and each size of coarse aggregate from the discharge <br />stream between batch bins and the weighing hoppers or between the batch hopper <br />and the mixer. <br /> <br />2. Provide an enclosed building not less than 200 square feet adjacent to the batch <br />plant, free from plant vibration and excessive plant noises, and furnished with all <br />necessary utilities including lights, water, room temperature control, and electrical <br />power. <br /> <br />1. Water Batching Equipment <br /> <br />I. Construct the water batching device so that the water will be discharged quickly <br />and freely into the mixer without objectionable dribble from the end of the <br />discharge pipe, and that leakage will not occur when the valves are closed. <br /> <br />2. Provide equipment capable of adjusting batch water by as little as 3 pounds per <br />cubic yard and a means for accurately introducing small increments of water into <br />each mixer after batching for occasional final tempering of the concrete. <br /> <br />( <br /> <br />J. <br /> <br />Central Mixers <br /> <br />1. Configure plant so that the mixing action of each mixer can be observed from a <br />safe location which can be easily reached from the control station. Provide the <br />operator the means to observe the concrete in the receiving hopper or buckets as it <br />is being dumped from the mixers. <br /> <br />2. Control each mixer with a timing device which will indicate the mixing period <br />and ensure completion of the required mixing period. <br /> <br />3. Equip the batch plant with an interlocking mechanism which will prevent <br />concrete batches from entering mixers which are not empty. <br /> <br />K. Truck Mixers <br /> <br />I. Equip truck mixers with a watermeter, accurate to within 1 percent of the total <br />mix water, located between the water supply and mixer. <br /> <br />2. The watermeter shall have a dial or digital indicator. <br /> <br />3. Equip truck mixers with a reliable revolution counter, visible from the operator <br />control area, for indicating the total number of revolutions of the drum for each <br />batch. <br /> <br />4. Reset the revolution counter to zero for each batch. <br /> <br />5. Attach a metal plate to truck mixers in a prominent place indicating the <br />manufacturer's recommended drum capacities, in terms of volume, and the <br />maximum and minimum speeds of rotation for both mixing and agitating. <br /> <br />Cast-in-Place Concrete <br />03300 - 15 <br />