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PGSF WMVD Storm and Combined Sewer - Construction Package 2 Cast-in-Place Concrete <br />Project No. 180162 03 30 00 - 23 <br /> <br />2) Take samples at the discharge gates of the bins feeding the weigh hopper. <br />Repeat sampling when the source of material is changed or when <br />unacceptable deficiencies or variations from the specified requirements of <br />materials are found. <br />3) Aggregate samples shall be tagged and their sources idenified. <br />b. Coarse Aggregate: <br />1) Take a sample weighing between 50 and 60 pounds after the batch plant is <br />brought up to full operation. <br />2) Take samples to obtain a uniform cross section, accurately representing the <br />materials on the belt or in the bins for sieve analysis. <br />c. Fine Aggregate: <br />1) Take samples as specified for coarse aggregate. <br />2) Take samples of sand when the sand is moist for sieve analysis and specific <br />gravity tests. <br />2. Concrete: <br />a. Take samples of plastic concrete in accordance with ASTM C172. <br />b. Take samples at the hopper of mixing equipment or transit mix truck, except as <br />noted in the Placing Concrete by Pumping subparagraph of the Conveying and <br />Placing article above. <br />C. Testing: <br />1. Aggregate: <br />a. A minimum of one test of coarse aggregate per 400 cubic yards of concrete used <br />and a minimum of one test of fine aggregate per 200 cubic yards of concrete <br />used shall be made to confirm continuing conformance with specifications for <br />gradation, cleanliness and sand equivalent. <br />b. A maximum of one test per day of each aggregate is required. <br />c. Repeat of the entire concrete mix design test program is required before source <br />changes will be accepted. <br />2. Concrete: <br />a. Strength Tests: <br />1) The strengths specified for the design mix shall be verified by the <br />independent testing laboratory during placement of the concrete. Verification <br />shall be accomplished by testing standard cylinders of concrete samples <br />taken at the job site. Cylinders shall be 4 by 8 inch or 6 x 12 inch. <br />2) Concrete samples shall represent the concrete placed in the forms. One set <br />of six standard 6 x 12 inch (or nine 4 x 8 inch) cylinders shall be cast of each <br />class of concrete for each 100 cubic yards or less, or for each 5,000 square <br />feet of slab or wall surface area placed per day. Provide additional cylinders <br />when an error in batching is suspected. Each set of cylinders are cast from <br />material taken from a single load of concrete. <br />3) Casting, handling and curing of cylinders shall be in accordance with <br />ASTM C31. For the first 24 hours after casting, keep cylinders moist in a <br />storage box constructed and located so that its interior air temperature will <br />be between 60 and 80 degrees F. At the end of 24 hours, the testing <br />laboratory will transport the cylinders to their laboratory.