Specifications include, but are not limited to: The City of West Des Moines, Iowa, solicits interested Contractors to submit bids for Portland Cement Concrete for street maintenance projects. The price quote shall include all costs for supplying, hauling, and waiting charges for supplying Portland Cement Concrete to the City based upon miscellaneous orders for street repairs. 1. Mix Number: • M-4, C-4, C-4WR, C-4 WR-C20, C-4 WR (modified) in accordance with Iowa DOT Standard Specifications Section 2301 and Iowa DOT Materials I. M. 529 as requested by the City. • Air entraining admixture: produce 6.5% + 1.0% air voids in fresh concrete measured by pressure method. 2. Proportion of adjustments: • Basis: When actual quantity of concrete is more than one hundred and one percent (101%) or less than ninety-nine percent (99%) of calculated quantity or if combination of materials does not produce quality of concrete specified. • Fine aggregate shall not exceed fifty percent (50%) of total aggregate in any adjustment. • Do not exceed maximum water-cement ratio specified. 3. Water quality and concrete consistency: • Use proper amount of mixing water to produce concrete of uniform consistency; adapt to mix, characteristics of materials used, methods of consolidation, weather conditions and slope of finished surface. • Modify proportion if maximum water-cement ratio does not produce workability; increase cement to aggregate proportion to produce specified degree of workability without exceeding maximum water-cement ratio.
