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<br />002421 <br /> <br />Durango Pumoing Plant - Stage 1 <br /> <br />( <br /> <br />d. Use Table 5, page 309, USBR Concrete Manual - Volume II as a guide for <br />determining the maximum water-cement ratio to ensure durability of <br />concrete. <br /> <br />8. Consistency <br /> <br />a. Provide concrete having a slump at placement not exceeding 2 inches plus <br />or minus. 1 inch for concrete in the tops of walls, bridge piers and <br />abutments, parapets, curbs, and slabs that are horizontal or nearly <br />horizontal and mass concrete. <br /> <br />b. Provide concrete having a slump at placement not exceeding 3 inches plus <br />or minus 1 inch for all other concrete. <br /> <br />c. Concrete exceeding the specified slump at the placement is unacceptable. <br /> <br />d. A lesser slump may be required whenever such concrete can be <br />consolidated into place by means of vibration. <br /> <br />e. The use of buckets, chutes, hoppers, pumps, transit mix trucks, or other <br />equipment which will not readily handle and place concrete of the <br />specified slump will not be permitted. <br /> <br />f. When type F or G chemical admixture is used to fluidize the concrete for <br />an unusual placing condition, provide concrete having a slump appropriate <br />for the placing conditions. <br /> <br />g. Provide concrete that is uniform is consistency from batch to batch. <br /> <br />h. To maintain concrete at the proper consistency, adjust the amount of water <br />and aggregates batched for concrete to compensate for variations in the <br />moisture content or grading of the aggregates as they enter the mixer. <br /> <br />I. Adding water in excess of the design water content to compensate for <br />stiffening of the concrete after mixing, known as retempering, will not be <br />permitted. <br /> <br />Water-Cement Ratio <br /> <br />9. <br /> <br />a. The maximum water-cement ratio shall be 0.45 by weight. <br /> <br />b. Net water-cement ratio, exclusive of water absorbed by the aggregates, <br />sufficiently low to provide adequate durability in concrete. <br /> <br />2.04 SOURCE QUALITY CONTROL <br /> <br />A. Cementitious Materials Testing and Acceptance: <br /> <br />I. False set: <br /> <br />a. When directed by Contracting Officer, test cement for compliance with <br />false-set requirement immediately before shipment while cement is still at <br />cement producer. <br /> <br />b. Testing frequency will be directed by Contracting Officer and will not <br />exceed one test per truck load (25 tons) of cement. <br /> <br />Cast-in-Place Concrete <br />03300 - 17 <br />