Design a Portland cement concrete mix for a loading dock driveway slab. The concrete will be exposed to deicing chemicals and subjected to freezing and thawing in a moist condition. This is severe environmental exposure. The slab is considered flat work for the purpose of determining minimum cement content. The concrete will be made from material that you have tested twenty times with a resulting standard deviation of 210psi. The concrete is to be designed for an f'c of 4500psi and a slump of 4 inches. The slab will be 20 feet by 40 feet by 5 inches. Compute the design and the weights of materials required to mix enough concrete for the slab. If 0.25 ounce of air entraining chemical per 100 pounds of cement per 1% of air will provide the correct amount of air compute the number of ounces you would need for the slab.
Coarse Aggregate: Nominal maximum size is 1 inch
Dry rodded unit weight is 100pcf
Bulk specific gravity is 2.55
Abosorption is 1.0%
Moisture content is 1.0%
Fine Aggregate: Fineness modulus is 2.90
Bulk specific gravity 2.82
Absorption is 2.0%
Moisture content is 1.0%