100 

 Spreading and heavy ramming 0.200 



$1.198 

 Foreman at $3.00 a day Ill 



Total cost of mixing 1 yd $1.309 



When machine mixing is done, batch, continuous and 

 gravity mixers can be used. Batch mixers are revolved 

 10 to 15 times to give one batch a thorough mixing. This 

 can be done in 1 to l 1 /^ minutes after charging. A mixer 

 can be charged, given 15 turns and discharged in about 

 3 minutes, or 200 batches in 10 hours; consequently the 

 output of the mixer depends on the size of batch. With a 

 good organization 300 batches can be turned out In 10 

 hours. 



About 12 h. p. Is used to run a % yd. mixer. A gaso- 

 line engine using ten gallons of gasoline per 10 hour day 

 at 12%c per gallon cost $1.25; 2 men will charge it, cost 

 $4.00; 1 man to dump, cost $2.00, making a cost per cu. 

 yd., $3.62; to this must be added the cost of wheeling to 

 mixer, making of runs and placing same, wheeling to 

 place of depositing, spreading, ramming, erection of hoists, 

 engineer, cost of engine, hoist, etc., depreciation. 



The price of sand and stone being obtained, the quan- 

 tities required per cu. yd. can be also taken from the 

 table and the cost found. Gravel and stone can be ob- 

 tained at prices ranging from 90c to $1.60. Sand, from 

 6*c to $1.50. Cement averages about $2 per barrel. 



An experienced gang, at 15c per hour, can mix and 

 shovel directly into place 1 cu. yd. at 80c. If wheeled, 

 9c per cu. yd. for the first 25 ft. and l^c for each addi- 

 tional 25 ft. should be added. A green gang will almost 

 double this cost. 



COST OF PLANT. 



Hoisting engine and boiler can be rented at $2 per day 

 for 30 days; for time exceeding 30 days a reduction of 

 rate down to $1 per day ought to be obtainable. For fuel 

 allow 1-3 of a ton of coal for each 10 h. p. per ten-hour 

 shift. Prices of mixers can be obtained from manufac- 

 turers. 



CONCRETE BREAKWATERS. 



These are generally cast In sections and then swung In- 

 to place by a derrick and grouted with Portland cement 

 mortar. This can be placed for $6.35 per cu. yd., using a 

 1:2^:5 mix. In Milwaukee, where 27% of the heart of the 

 mass above low water was natural cement concrete cost- 



