Calculate the weight of cement, fine aggregate (sand), coarse aggregate (rock) and gallons of water to mix a 1:2:4 concrete mix design ratio. The structure is a small utility pad that is 5’ x 5’ and is 5 inches in depth. Make sure you make enough, use the 10 percent rule. Use a water to cement ratio of 0.50. Weight of Concrete = 150 lbs per ft3 1 gallon of water = 8.34 lbs. How many yards of concrete were required

0 ww C. 6.31 A concrete mix includes the following ingredients per cubic foot: a. Cement = 25 lb b. Water = 11 lb c. No admixture Table P6.31 shows possible changes that can be made to the mix ingredi- ents. Indicate in the appropriate boxes in the table what will happen in each case for the workability and the ultimate compressive strength as increase, decrease, or approximately the same. TABLE P6.31 to dignope Cement (lb) 25 28 25 25 25 25 25 amigur Water (lb) 15 11 11 8 11 11 11 Admixture None None Water reducer Water reducer Superplasticizer Air entrainer Accelerator What Will Happen? www.10345 Ultimate Compressive we Strength Workability

Determine the quantities of materials required per cubic yard to create a concrete mix. The specifications require a maximum size aggregate of 1½ in., a minimum cement content of 5½ sacks per cy, and a maximum water- cement ratio of 0.60. Assume 6% air voids (cement, 470 lb per cy; water, 4.52 cf/cy; fine aggregate, 1,068 lb/cy; coarse aggregate, 1,986 lb/cy).

6.32 The results of an experiment to evaluate the effects of a water reducer are shown in Table P6.32. a. Calculate the water-cement ratio in each of the three cases. b. Using water reducer, how can we increase the compressive strength of concrete without changing workability? Refer to the appropriate case in the table. Chapter 6 Portland Cement, Mixing Water, and Admixtures c. Using water reducer, how can we improve workability without changing the compressive strength? Refer to the appropriate case in the table. d. Using water reducer, how can we reduce cost without changing workability or strength? (Assume that the cost of the small amount of water reducer added is less than the cost of cement.) Refer to the appropriate case in the table. e. Summarize all possible effects of water reducers on concrete. TABLE P6.32 Without Water Reducer With Water Reducer 735 368 2 4,100 Case 1 Case 2 Cement content, lb/yd³ Water content,* lb/yd³ Slump, inches 28-Day compressive strength, psi *Assume…