The columns for a building in central Long Island are to be madeof concrete with the following specifications: • Design compressivestrength: 4500 psi, based on 20 tests of samples having a standarddeviation of 600 psi • Non-air entrained, and clear space betweenrebar: 1.5 inch • Fine aggregate: G = 2.350, FM = 2.5 • Coarseaggregate: G = 2.65, bulk density = 3000 lb/cy Determine thefollowing: i. w/c ratio, largest nominal max. coarse aggregatesize, % coarse aggregate, % air (2 pts.) ii. weight of water,weight of cement, and weight of coarse aggregate to be used percubic yard of concrete (1 pt.) iii. weights and volumes of water,cement, air, coarse aggregate, and fine aggregate needed to mix a15-yard batch of this mix (3 pts.) Also: • Specify two admixturesthat might be used for this mix based on the provided information,and why to use it. (2 pts.) • Why we might create a composite ofthis concrete poured into a PVC (polyvinyl chloride) sleeve forthese columns? (Give specific reasons based on the characteristicsof the individual materials.) (2 pts.)
