Ill 



Mixing Concrete: Mix cement and sand dry until the 

 mixture shows a uniform color, then place the stone on 

 top, wet slightly and mix well together by shoveling over 

 three or four times; add only sufficient water to make the 

 sand and cement "stick to the stone, so that when handled 

 by a shovel it will not crumble or fall off. Too much 

 water weakens concrete. 



Proportions for Concrete Work: Varying proportions of 

 sand and stone can be mixed with one part of cement 

 and give good results, but for all ordinary purposes, such 

 as sub-surfaces of sidewalks, cellars or street paving, 

 mill or machinery foundations, house foundations, retain- 

 ing walls, cisterns, reservoirs, etc., one part cement, two 

 parts of sand and five parts of broken stone, or one part 

 of cement, three parts of sand and seven parts of broken 

 stone will give excellent results; enough sand should be 

 used to fill all the voids between the stones. Architects 

 usually state the proportions for the concrete in building 

 specifications, and vary the proportions of sand and stone 

 to suit the character of the work. If absolutely water- 

 tiKht work is required, the face of concrete should be 

 plastered on the side facing the water with a mixture of 

 one and one-half parts of sand to one part cement. Never 

 mix large quantities, but only as much as can be put in 

 place within fifteen or twenty minutes after mixing. 



Laying Work: Ram the mixture well into place with a 

 tamping iron or heavy wooden rammer, until it shakes 

 like jelly and until the water comes to the surface; lay 

 quirkly, so that the layers adhere to each other, and in 

 cold weather, to avoid freezing, use 1 Ib. of salt to 15 or 

 18 gal. of water. In hot weather, after concrete has set 

 (say 12 hours) wet frequently with water, especially on 

 sidewalk work. Cover unfinished work over night or over 

 Sunday to prevent surface drying out, thus insuring a 

 good joint when work is resumed. 



Laying Pavements: Depth of excavation depends greatly 

 on soil; if walks are bounded on each side by soil. 15 to 

 IS in. should be excavated and filled up to within 4 in. of 

 level with good ashes, clinker, gravel or stone sprinkled 

 and rammed well; this is necessary to prevent frost get- 

 ting under pavement. Stakes and strips (2 in. x 4 in.) 

 should be set on the outside to keep the walk straight; 

 then fill to within * in. of top strips with concrete, mixed 

 proportionately as stated in "Proportions for Concrete 

 Work;" ram well, as previously directed; before the sub- 



