Specifications include, but are not limited to: 4.1. Detailed Material The contractor furnishing these items shall be experienced in Formulation and Production of such items and shall furnish evidence, if requested, by the City of having supplied similar items. The bidder shall be an established supplier of the items requested. The mix furnished shall be of the highest quality as to formulation and materials used. 4.2. Mix (a) The concrete mix shall consist of Portland cement, coarse aggregate, fine aggregate and mineral filler if required. It shall be proportioned according to these specifications. (b) The mixture shall contain from five to seven and a half (5 – 7.5) sacks of cement, whichever is specified, per cubic yard of concrete. There shall be not more than 0.85 cubic foot of coarse aggregate (dry loose volume) in each cubic foot of concrete. If ordered, mineral filler shall be added to the mixture. 4.3. Mineral Filler (a) A mineral filler may be used, if necessary, to improve the workability or plasticity of the concrete mixture. It shall be either stone dust, sand or crushed oyster shell dust or a combination of any of them. It shall be clean and of acceptable quality. When tested with standard laboratory sieves, the mineral filler shall conform to the following requirements: Passing 30 mesh sieve 90-100% Passing 200 mesh sieve 0-100% (b) When mineral filler is used, it must be batched and weighted separately and the amount shall not exceed (15) percent of the weight of the fine aggregate. 4.4. Cement (a) The cement used shall be a Type I or Type III of a standard brand of Portland cement which shall conform to ASTM Designation C150. Type III cement shall be used when high early concrete is required. If the use of high early strength cement is not specified, and the Contractor desires to use it, he shall obtain written permission of the Engineer and shall assume all additional cost incurred by the use of such cement.