Thikty-sixth Annual Convention 1013 



confuse a 1 :2 :4: mixture with a 1 :() mixture, the former is 25 

 per cent, richer iu cemeut. For measuring, bottomless boxes 

 can be nuide of known volume, or with practice a man will meas- 

 ure by shovelfuls very accurately for ordinary work. This 

 method allows the overseer to readily call for a mixture in pro- 

 portion to the materials and to the construction at hand. A bag 

 of cement contains eight ordinary shovelfuls ; therefore, for a bag 

 batch of a standard mixture it calls for sixteen shovelfuls of sand 

 and thirty-two shovelfuls of gravel. 



l^ext, after proper materials and proportions, comes proper 

 mixture and handling. The mixing should continue until the 

 color is uniform, regardless of times turned. This point can be 

 determined by drawing the flat of the shovel across the heap. If 

 not properly mixed, streaks of sand or cement will show. In espe- 

 cially fine work requiring careful mixing, the mortar — namely, 

 the sand and the cement — should be mixed separately before 

 adding the coarse material, which can be added with a minimum 

 of labor after the mortar has been mixed wet, because the bulk of 

 the material only has to be turned a few times. The mortar should 

 be as dry as possible during mixing, for best results. If the sand 

 is damp the cement will ball and stick to the grains in contact 

 and delay filling the voids. However, by turning and wetting 

 more, they adjust themselves properly. We have found that water 

 added in a spray from hose or sprinkler during the turning gives 

 most satisfaction. A surplus of water separates the cement par- 

 ticles from the s'and grains. The mixing board should be large 

 and roomy according to ^the number of mixers, watertight sur- 

 faced, and having a low rim to prevent surplus water carrying 

 portions of cement off the board. The board should be located 

 with reference to materials and to position of delivery to forms. 

 Plans can be often laid so that the materials can be shoveled di- 

 rectly to the mixing board and then directly to forms. The final 

 turn should be with reference to placing. 



Good runways and metal-tray wheelbarrows should be provided, 

 if there is any distance between points. For wall work, run- 

 ways should be placed so that the wheelbarrows can be dumped 

 directly into the forms. Short-handled, square-pointed shovels are 

 the proper turning tools and are important if a quantity of ma- 



