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<br />VU(..'l>JU <br /> <br />Durango Pumoing Plant - Stage I <br /> <br />Amendment 00 I <br /> <br />and steel fibers. Ifthese limits cannot be consistently met, then batching shall be <br />by direct weighing. <br /> <br />3. To permit accurate, consistent proportioning of aggregate, augers used in dry-mix <br />process shotcrete delivery equipment shall be constructed of abrasion-resistant <br />material to prevent rapid and excessive wear. Recalibrate auger feed as necessary <br />to keep them within the prescribed percent batching accuracy. <br /> <br />4. The percentage of surface moisture in the sand (ASTM C 566 and C 128) shall be <br />3 to 6 percent, by weight, and shall be controlled within such range as may be <br />necessary to maintain uniform feed and to avoid choking the delivery equipment. <br /> <br />5. Waste shotcrete batches containing cementitious materials which have been in <br />contact with damp aggregate or other moisture for more than 2 hours at the <br />Contractor's expense; or additional cementitious material shall be thoroughly <br />mixed into the batch. <br /> <br />B. Wet-Mix Process Hatching: In accordance with the requirements for concrete batching in <br />Section 03300 - Cast-in-Place Concrete. <br /> <br />3.02 MIXING <br /> <br />A. Mixing for the dry-mix process: <br /> <br />I. Uniformly add and mix cementitious materials, sand, coarse aggregate, <br />admixture, and steel fibers before being fed into the delivery equipment: <br /> <br />a. If liquid accelerator is used, it shall be added at the nozzle. <br /> <br />b. Machine mixing of the dry ingredients, except the accelerating admixture <br />will be required. <br /> <br />2. Mixers used to mix dry ingredients without full amount of mix water added must <br />discharge the batch without segregation. Mixers will be tested for uniformity of <br />coarse aggregate content from front to back of the mixer. The maximum <br />permissible difference in percentage of coarse aggregate by weight of sample <br />shall not exceed 6 percent within a batch. <br /> <br />3. The discharge nozzle for the dry-mix process shall be equipped with a manually <br />operated water injection system of sufficient pressure to provide an even <br />distribution of water into the dry shotcrete mixture at the nozzle. The water valve <br />shall be capable ofready adjustment to vary the quantity of water and shall be <br />convenient to the nozzleman. <br /> <br />4. Mixing for the wet-mix process shall be in compliance with the requirement for <br />concrete mixing in Section 03300 - Cast-in-Place Concrete. <br /> <br />3.03 PLACING <br /> <br />A. Apply a 3-inch layer of shotcrete over all shale lenses exposed on v..: I excavation slopes, <br />after chain link fabric has been installed, and as directed by the Contracting Officer. <br /> <br />Shotcrete <br />03370 - 5 <br />