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2.04 ADMIXTURES <br /> Admixtures to be used in concrete shall be subject to prior acceptance by the Engineer. The admixture <br /> shall maintain the same composition and performance throughout the work as the product used in the <br /> concrete proportioned established in accordance with ACI 211. Admixtures containing chloride ions shall <br /> not be used in pre-stressed concrete or concrete containing aluminum embedments. <br /> A. Air Entrainment <br /> An air entrainment agent shall be used in all concrete. The agent used shall conform to ASTM <br /> Designation C260. <br /> The amount of air entraining agent used in each concrete mix shall be such as will effect the <br /> entrainment of the percentage of air shown in the following tabulation in the concrete as <br /> discharged from the mixer at the point of placement. <br /> Maximum Size of Coarse Total Air,Percent By <br /> Aggregate(inches) Volume.of Concrete <br /> 3/8" 7.5 f 1 <br /> 3/4" 6.0 f I <br /> 1-1/2" 5.5 f I <br /> B. Water Reducing,Set-Controlling Admixture <br /> The Contractor shall use a water-reducing,set controlling concrete. A water-reducing admixture <br /> shall be used in all concrete and shall conform to ASTM Designation C494,specifically Types A, <br /> B,C,D,and E. <br /> C. Finely Divided Mineral Admixtures <br /> Mineral admixtures shall be limited to fly ash conforming to ASTM Specification C618. <br /> 2.05 BATCH NG <br /> Measuring and batching of materials shall be done at a batching plant. <br /> A. Portland Cement <br /> Either sacked or bulk cement may be used. No fraction of a sack of cement shall be used in a <br /> batch of concrete unless the cement is weighed. Bulk cement shall be weighed on scales separate <br /> and distinct from the aggregate hopper or hoppers. Batching shall be such that the accuracy of <br /> batching shall be plus or minus one percent of the required weight. <br /> B. Water <br /> Unless water is to be weighed,the water-measuring equipment shall include an auxiliary tank <br /> from which the measuring tank shall be filled. In lieu of the volume method,the Contractor will <br /> be permitted to use a water metering device. <br /> C. Aggregates <br /> Aggregates shall be handled from stockpiles or other sources to the batching plant in such a <br /> manner as to secure a uniform grading of the material. Aggregates that have become segregated, <br /> or mixed with earth or foreign material,shall not be used. Batching shall be so conducted as to <br /> result in the weights of material required for each type aggregate within a tolerance of 2%. <br /> Section 03310-Page 2 of 8 9/17 <br />