158 CEMENT AND CONCRETE 



thin board. When the job is a fairly large one, do not 

 mix less than the amount produced when a sack of ce- 

 ment is taken as a unit. It is desirable to complete 

 the job without interruption after it is started. In 

 case it is necessary that the work be discontinued for a 

 period, see that the surface of the dry concrete is 

 cleaned and thoroly wet down before fresh concrete is 

 poured. 



5) To insure against cracks in a concrete wail, a few rein- 

 forcing rods bent at right angles and placed at succeed- 

 ing heights of 12 to 18 inches in the corners, will be in- 

 valuable. Reinforcing placed around openings is also 

 recommended. 



6) The forms on a wall of more than six feet in height 

 should stay on several days. The forms on walls only 

 two or three feet high may be removed in forty-eight 

 hours. As to finishing the surface of the wall, follow 

 instructions given under this heading in Sec. 142. 



Note: When a wooden superstructure is to be built on a 

 concrete foundation, it is advisable to set some bolts in the 

 concrete at intervals of every five or six feet, to which the sills 

 may be fastened. 



144. Constructing Fence Post (Fig. 153). 



Requirements: To construct line fence posts and corner and 

 end posts requiring quaky or wet mixtures and rein- 

 forcing. 



Tools Needed: Shovels, buckets, measuring box, screen, mix- 

 ing platform, straight-edge, flat trowels and suitable 

 forms or molds, or woodworking tools suitable for con- 

 structing same. 



