;].— SOME NOTE.S UPON THE APPLICATION OF 

 KEINFOl^vCEI) CONCRETE. 



By Fkank W. Waldi;ux, A.M.I.C.E. 



Although the coinbiuation of conci'ete and metal, called ''ferro- 

 eonci-ete "' or "reinforced concrete," has only been lately introduced 

 into South Africa, it has for many years been used with success upon 

 the Continent aiitl in America. In Great Biitain, owing to the con- 

 servative ideas of the engineers and architects and the attitude of the 

 Local Government Board against it, it has not been e.vtensively made 

 use of, but is now steadil}'^ becoming more popular. Regarding the 

 early history of reinforced concrete, it has been stated that the demon- 

 stration of the practical value of the combination of metal and concrete 

 has been attributed to a French gardener, M. Joseph Monier, who in 

 18G7 made large pots for shrubs of concrete with a metal reinforcement. 

 We are also told that several methods of its application were proposed 

 by a French engineer, M. Francois Coignet, in 1861, and that an 

 exhibit of this material was sliown at the Paris Exhibition as early 

 as 18-55. 



The employment of metal embedded in concrete and brickwork 

 has, however, been discovered in ancient structures, showing that 

 although the introduction of metal into these structures may not 

 have been carried out on a scientific basis, it is evident that rein- 

 forcement with metal was looked upon even in early times as an 

 etlicient manner of bonding such )naterials as concrete, brickwork 

 and masonry. 



In recent years, with the increasing demand for cheap structures 

 to replace timber, steel, iron or masonry, engineers directed their 

 attention to the scientific application of reinforced concrete, with the 

 result that the foi-mer rule of thumb method of designing structures 

 of this material has been superseded by scientific ones, and it is now 

 possible, aided by recent research, to calculate with considerable safety 

 the resisting moments for various members of structures subjected to 

 bending and compression ; hence the growing confidence in the use of 

 reinforced concrete, not only as an economical material, but for its 

 durability and adaptability to artistic treatment. 



The uses to which reinforced concrete has been put to the 

 present time are as follows : bridges, culverts, sewers, tunnels, water 

 pipes, wharves, jetties, reservoirs, weirs, dams, coal and ore staiths, 

 railway viadu(;ts, aqueducts, buildings of all descriptions, telegraph 

 poles, factory chimneys, doors, windows, and more recently barges, 

 lx)ats, pontoons, itc. All these have been successfull}' constructed, 

 fully demonstrating the possibilities of reinforced concrete as an 

 efficient building material. 



It is not proposed in this paper to deal with the theory of 

 beams, columns, floors, S:c., made with reinforced concrete, but for 



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