Answer:
Explanation:
Ans) Given batch weight of each component :
Cement = 700 lb
Water = 315 lb
Coarse aggregate = 1575 lb
Fine aggregate = 1100 lb
Part 1) Amount of water = 328.5 lb
Amount of water is needed to be increased if the aggregates has absorption capacity, To maintain constant water cement ratio, the mixing water is increased because some of the water is absorbed by aggregates.
Amount of water absorbed = 328.5 lb - 315 lb = 13.5 lb
Total amount of aggregates = 1575 + 1100 = 2675 lb
=> % Absorption capacity = 13.5 x 100 / 2675 = 0.5 %
Hence, new amount of Coarse aggregate = (1 - 0.005) x 1575 lb = 1567.125 lb
New amount of fine aggregate = (1 - 0.005) x 1100 = 1094.5 lb
Since, water cement ratio is maintained constant , amount of cement remains unchanged
=> Volume of water = 328.5 / 62.4 = 5.26 ft3
=> Volume of cement = 700 / (3.15 x 62.4) = 3.56 ft3
=> Volume of coarse aggregate = 1567.125 / (2.4 x 62.4) = 10.46 ft3
=> Volume of fine aggregate = 1100 / (2.4 x 62.4) = 7.34 ft3
Volume of air = 2% = 0.02 x 27 = 0.54 ft3
Total concrete volume = 5.26 + 3.56 + 10.46 + 7.34 + 0.54 \approx 27 ft3 = 1 yd3
Hence, calculated amount of each component is correct
Part 2) We know, minus sign indicated that the aggregate will absorb some moisture from concrete, hence mixing water amount needed to be corrected .
=> Amount of water absorbed by coarse aggregate = 0.01 x 1567.125 lb = 15.67 lb
=> Amount of water absorbed by fine aggregate = 0.02 x 1094.50 lb = 21.89 lb
Total amount of water absorbed = 15.67 + 21.89 = 37.56 lb
To maintain same water cement ratio, amount of mixing water is needed to be increased
=> Corrected amount of mixing water = 328.5 lb + 37.56 lb = 366 lb
=> Corrected amount of coarse aggregate = (1 - 0.01) x 1567.125 = 1551.45 lb
=> Corrected amount of fine aggregate = (1 - 0.02) x 1094.5 = 1072.6 lb
Part 3) We know,
Unit weight = Sum of weight of each material / Total volume
=> Sum of weight = 366 + 700 + 1551.45 + 1072.6 = 3690.05 lb
Total volume = 1 yd3 or 27 ft3
=> Expected Unit Weight = 3690.05 lb / 27 ft3 = 136.67 lb/ft3
Also, Concrete Yield = Weight of all components / Unit weight of concrete
=> Yield = 3690.05 / 136.67 = 27 ft3 or 1 yd3
