HIGHWAY CONSTRUCTION 



121 



Fig. 73. Tamper. 



The varieties most extensively used in the United States are 

 known by the names of granolithic, monolithic, fcrrolithic, kosmocrcte, 

 metalithic, etc. 



The process of manufacture is practically the same for all kinds, 

 the difference being in the materials em- 

 ployed. The usual ingredients are Port- 

 land cement, sand, gravel, and crushed 

 stone. 



Artificial stone for footway pave- 

 ments is formed in two ways namely, 

 in blocks manufactured at a factory, 

 brought on the ground, and laid in the 

 same manner as natural stone; or the raw 

 materials are brought upon the work, pre- 

 pared, and laid in place, blocks being formed by the use of board 

 moulds. 



The manner of laying is practically the same for all kinds. The 

 area to be paved is excavated to a mini- 

 mum depth of 8 inches, and to such great- 

 er depths as the nature of the ground may 

 require to secure a solid foundation. The 

 surface of the ground so exposed is well 

 compacted by ramming; and a layer of 

 gravel, ashes, clinker, or other suitable material is spread and consoli- 

 dated ; on this is placed the concrete wearing surface, usually 4 inches 



thick. As a protection against the lifting 

 effects of frost, the concrete is laid in 

 squares, rectangles, or other forms hav- 

 ing areas ranging from 6 to 30 square 

 feet, strips of wood being employed to 

 form moulds in which the concrete is 



placed. After the concrete is set, these strips are removed, leaving 

 joints about half an inch wide between the blocks. Under some 

 patents these joints are rilled with cement; under others, with tarred 

 paper; and in some cases they are left open. 



Tools Employed in Construction of Artificial Stone Pavements. 

 Tampers (Fig. 73). Cast iron, with hickory handle; range from 6 

 by 8 inches to 8 by 10 inches. 



Fig. 74. Quarter-Round. 



Fig. 75. Jointer. 



