BUILDING CONSTRUCTION 131 



Stones or bricks broken to pass a 3-inch ring . 4 parts. 



Clean sharp sand ...... 2 parts. 



London Portland cement . . . . .1 part. 



Water in sufficient quantity. 



The material should be mixed on a close board, or stone or 

 cement pavement (not on soil), turned over twice dry and once 

 after being wet, immediately thereafter being turned into the founda- 

 tion tracks. 



Cement Plaster, consisting of clean, sharp sand and Portland 

 cement mixed in three or four to one proportions, is used for 

 rendering or plastering the inner or outer surfaces of walls, parti- 

 tions, cow byres, divisions, piggery partitions, &c. Care should be 

 taken to avoid using a plaster too rich in cement, otherwise hair- 

 cracks or crazes will develop. A sand-faced finish is preferable to 

 a polished one in this respect, but it is nevertheless more difficult to 

 clean, as in the case of a sick loose-box. Cement plaster lends 

 itself to the introduction of rounded corners and angles, and to 

 a hygienic finish adjoining metal fittings in stables. 



Harling or Rough-Casting for the outer face of walls consists 

 of cement plaster finished on the surface with pebble or crushed 

 granite dashing. 



Reinforced Concrete consists of fine concrete strengthened with 

 iron or steel rods or expanded steel, so placed that the reinforcement 

 will take up the tensile strains set up in the concrete. It is now 

 extensively used for the formation of stanchions, beams, partitions, 

 retaining walls, tanks, stall divisions, upper floors, &c. 



ASPHALTS. True mineral rock asphalt is used in different 

 forms for paving roadways, covering platform roofs, and lining the 

 walls of basements to exclude damp. 



Mineral rock asphalt is a natural limestone impregnated with 

 natural bitumen. When the rock is quarried it is of a chocolate 

 colour, very fine in grain and thoroughly and evenly impregnated 

 with bitumen to the extent of from 6 to 14 per cent., the remaining 

 properties being pure limestone. This rock is found principally 

 in the Val de Travers (Switzerland), Seyssel and Montrottier 

 (France), and Limmer (Hanover). 



Mineral rock asphalt may be laid in two ways, viz., " powder- 

 work " and " mastic-work." 



Poivder-lVork is used for roadways. The material is prepared 

 by grinding the rock to a fine powder, which is then roasted in a 

 special plant, conveyed hot in steel waggons to the work, and spread 

 on a solid concrete foundation. The powder is immediately beaten 

 into position with hot iron rammers, and finished to a uniform 



