concrete mix design
A concrete mix design for a highway project requires 590 lb/yd3 of cement. On a weight basis, the mix design has the proportions 1:2.25:3.25. The aggregates are SSD and have specific gravities of 2.65 for both the fine and the coarse aggregate. The specific gravity of the cement is 3.15. The water/cement ratio is most nearly
A. 0.37
B. 0.46
C. 0.54
D. 0.68
Use your mix ratio to solve for all weights (lb)
Cement: (1)(590) = 590 2) Sand: (2.25)(590)= 1327.5 3) Gravel: (3.25)(590) = 1917.5 4) Water=?
Solve for Volumes (CY)
Cement: (590)/(3.15 x 62.4 x 27) = .11 CY 2) Sand: (1327.5)/(2.65 x 62.4 x 27) = .297 3) Gravel: (1917.50)/(2.65 x 62.4 x 27) = .429 CY 4) Water= ?
Sum the Volume and assume a per 1 CY mix--> 1CY Total= .836 - (V_water) --> V water = .164 CY.
.164 CY x 27 ft3/CY = 4.428 ft3 Water. ---> 4.428 ft3/.134 ft3/gallon = 33.045 gallons Water.
33.045 gallons x 8.3453 lb/gallon = 275.77 pounds Water for the entire mix.
---> W/C ratio = 275.77 lb/(590 lb) = .46
