Question
2. Calculate the w/c ratio given the following information for a 9 yd load of concrete (note that w/c can also be found as w/cm ratio; for practical purposes both mean the same) Type I portland cement Slag cement Water (batch) Coarse aggregate (SSD) Fine aggregate (SSD) Slump Air content Density 3150 lbs 1800 Ibs 2475 lbs 15750 lbs 12150 lbs 4.5 inches 6.3% 144.6 lb/ft 3. If 30 gallons of water is added to the ready mix truck upon arrival at the construction site, re-calculate the w/c ratio for question 2
Explanation / Answer
Ques 2:
w/c ratio = Wt. of water / Wt. of cement
= 2475 / (3150 + 1800)
= 0.5
Ques 3:
Excess water added = 30 gallons = (30 x 8.35) lb = 250.5 lb.
therfore new w/c ratio = (2475 + 250.5) / (3150 + 1800)
= 0.5506