CONCRETE: BUILDINGS 271 



Surface Finish. Where it is desired to imitate stonework, imita- 

 tion joints are formed in the face of the wall and the surface is either 

 picked while the concrete is yet tender or is tooled after the concrete 

 has hardened. Bush hammering of concrete walls can be done by an 

 ordinary workman for from i*/ to 2 cts. per sq. ft. Where the con- 

 crete is coarse a coating of cement mortar may be applied as the con- 

 crete is placed in the molds by means of a piece of sheet steel placed 

 from I to 2 inches from the forms; the cement mortar, usually made 

 of I part Portland cement and 2 parts sand, is then rammed into the 

 vacant space, after the main body of the concrete has been rammed in 

 place, and the piece of sheet steel is removed. 



The preparation of the forms requires considerable study to obtain 

 a smooth surface and unbroken corners. The use of matched or 

 tongued-and-grooved stuff is not desirable as the concrete fills the open- 

 ings made by shrinkage and there is no room to expand. Unmatched 

 boards dry apart and let the water in the concrete leak out, carrying 

 with it some of the cement. The best way to build the forms is to use 

 narrow stuff and bevel one edge of the boards ; the sharp edge of the 

 bevel lying against the square edge of the adjoining board allows the 

 edge to crush when swelling and closes up the joint. A coat of soft 

 soap applied to the forms before filling, prevents the concrete from ad- 

 hering. The soap should be scraped and brushed off with a steel 

 brush as the forms are removed. 



For description of concrete round house at Moose Jaw, Canada, 

 see Part IV. 



