Design the concrete mix according to the following conditions:

Design Environment

Pavement slab, subjected to freezing

Required design strength = 21 MPa

Slab thickness = 300 mm

Statistical data indicate a standard deviation of compressive strength of

1.7 MPa is expected (more than 30 samples).

Only air entrainer is allowed.

Available Materials

Air entrainer: Manufacture specification is 9.5 mL/1% air/100 kg

cement.

Coarse aggregate: 2 in. nominal maximum size, crushed stone

Bulk oven-dry specific gravity = 2.573, absorption = 2.8,

Oven-dry rodded density = 1922 kg/m3

Moisture content = 1,

Fine aggregate: Natural sand

Bulk oven-dry specific gravity = 2.540, absorption = 3.4,

Moisture content = 4.5,

Fineness modulus = 2.68