of the right proportions of cement and water in order to obtain a suspension with about 15 by weight of cement this mixing is preferably done as a batch operation to this end bin 34 is provided with load cells 35 for measuring into said bin 34 a predetermined quantity of cement powder normally about 4 tons by opening and closing valve 32 filling bin 34 with said predetermined amount of cement may be made an automatic operation by means of controlling means 37 acting on valve 32 in response to signals from cells 35 etc in a manner known in the art water is added to the cement in bin 34 by means of pipe 38 having valve 39 to obtain a mixture of 15 of cement by weight this addition of water can also be made automatically utilizing controlling means 41 and water flow measuring device 43 in a manner known in the art the suspension of concrete in water will be understood to be a very thin slurry by contrast the literature states typical concrete to be in a ratio of 1 concrete 2 sand and 4 gravel with 100 lbs of cement to 6 gallons of water this would be 100 lbs of cement to 10 3 lbs of water or 91 concrete even before the sand and gravel is added to facilitate filling the bin 34 the latter is provided with a remote vent pipe 45 according to broader aspects of this invention the bin 34 could be modified to a continuous flow operation or even be eliminated altogether by feeding cement and water.