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<br />002415 <br /> <br />Durango Purnnin. Plant - Stage 1 <br /> <br />Deleterious substances <br /> <br />Maximum percent by <br />weight, in coarse <br />aggregate as batched <br /> <br />Lightweight material (ASTM C 123 <br />using a solution ofzinc chloride) <br /> <br />2 <br /> <br />Friable particles (ASTM C 142) <br /> <br />0.5 <br /> <br />Other deleterious substances <br /> <br />0.5 <br /> <br />Maximum allowable sum of all the <br />above deleterious substances <br /> <br />2 <br /> <br />5. Finish screening <br /> <br />I <br /> <br />h. <br /> <br />I. <br /> <br />a. <br /> <br />Washing and finish screening equipment shall be subject to approval by <br />the Contracting Officer. <br /> <br />Separate coarse aggregate into nominal sizes during aggregate production. <br /> <br />Just prior to batching, rewash coarse aggregate by pressure spray and <br />finish screen on multideck vibrating screens capable of simultaneously <br />removing undersized and oversized aggregate from each ofthe nominal <br />aggregate sizes. <br /> <br />During intermittent batching, if variations occur in water content of <br />aggregate entering the batcher, remove excess free moisture with a <br />dewatering screen after the finish screens. <br /> <br />Finish screens may be mounted over the batching plant or on the ground <br />adjacent to the batching plant. <br /> <br />Mount finish screens so that screen vibration will not be transmitted to the <br />batching bins or scales and will not affect the accuracy of the weighing <br />equipment in any other manner. <br /> <br />Provide a method and rate of feed for finish screening so that the screens <br />will not be overloaded and that the screening will result in a finished <br />product which meets the grading requirements ofthese specifications. <br /> <br />Feed coarse aggregate to the finish screens in a combination or alternation <br />of nominal sizes which will not cause noticeable accumulation of poorly <br />graded coarse aggregate in any batching bin. <br /> <br />Pass the finish-screened aggregates directly to the individual batching bins <br />in such a manner as to minimize breakage. <br /> <br />b. <br /> <br />c. <br /> <br />d. <br /> <br />e. <br /> <br />f. <br /> <br />g. <br /> <br />Cast-in-Place Concrete <br />03300 - II <br />