The mix shall conform to the following design: C-3WR-C15-S20 Approximate Quantity: 500 CY 1. Compressive strength of 4000 PSI in 28 days. 2. Minimum cementitious of 571 pounds per cubic yard. 3. Maximum water/cement ratio of 0.45 4. F ash may be used in place of C ash. 5. An approved water reducing admixture shall be used, conforming to ASTM C-494. 6. The use of calcium chloride shall not be allowed unless specifically approved by the Engineering Division. 7. All Portland Cement Concrete used shall contain an air entraining admixture, conforming to ASTM-C260 in proper amounts, to obtain 6.5% +/- 1% at the point of discharge. 8. All ready mix concrete and materials shall meet the requirements of the latest ASTM specification for Ready Mix Concrete, designation C-94 and the Iowa DOT specifications. All aggregates incorporated into ready mix concrete shall conform to ASTM C-33 and C-40 and the Iowa DOT specifications. 9. Ready mix concrete shall be mixed for a minimum of 70 revolutions, at a speed designated by the manufacturer. If water is to be added at the site to produce a workable slump, the mixer shall be turned an additional 30 revolutions, at mixing speed, but the water/cement ratio may not be exceeded.
