Question

Concrete is required for an interior concrete column in a commercial building in Corvallis, Oregon. A specified compressive strength, f’_c , of 4000 psi is required at 28 days using an ASTM C 150 Type I. The design calls for a minimum of 3 in. of concrete cover over the reinforcing steel. The minimum distance between reinforcing bars is 2.5 in. A slump of 4 inches should be the target. No statistical data on previous mixes are available. Follow mixture proportioning according to Portland Cement Association (PCA) - Design and Control of Concrete Mixtures, Kosmatka and Wilson, 2011, 16^th Edition.  

Materials Available:

ASTM C 150 Type I/II Cement

            Relative density of 3.15

Coarse Aggregate: well-graded ¾ in. maximum-size aggregate (MSA), local river gravel

            Oven-dry specific gravity: 2.60

            Absorption: 1.2%

            Oven-dry rodded bulk density: 102.4 lb/ft³

            Moisture content of coarse stockpile: 3.0%

Fine Aggregate: well-graded, local natural sand

            Oven-dry specific gravity: 2.55

            Absorption: 2.0%

            Moisture content of fine stockpile: 3.8%

            Fineness Modulus: 2.60

Determine:

1. The theoretical mixture proportions of all concrete constituents (fine aggregate, coarse aggregate, water, cement, chemical admixtures (if specified)) based on 1 yd³ of concrete and remember this is based on oven dry aggregates.  

Answer 1