216 



On Concrete as a Building Material for 



Fig. 3. — Materials for making Concrete in layers. 



aa. Cement or Lime. lb. Sand or Fine Stufl. 



cc. Gravel or Ashes 



(Id. Rough Material. 



I must again mention that the lime should be thoroughly 

 slaked, the proportions being one part lime to six or seven of 

 broken material, both large and small. 



These should now be thoroughly mixed together in a dry 

 state, by turning the mass over twice. Commencing at the 

 centre A, Fig. 4, and throwing over towards the right and left, 

 the mass would be divided into two heaps, as B, C, Fig. 5,. 

 which should be again thrown together in the direction of the 

 arrows, and would again form one heap as D, Fig. G. 



Figs. 4, 5, and 6. — Illustrating the mode of mixing Materials for 

 making Concrete. 

 Fig. 4. Fio;. 5. 



Fis. 6. 



Water should now be sparingly added, and then the whole 

 thrown back again in two heaps, and again back to one as first 

 described, so that the various materials may be thoroughly 

 incorporated together. 



The mixture is now ready for use, and should be at once 

 wheeled to the building and thrown into the trench or mould, as. 

 the case may be. 



Cement Concrete (chiejiy for Walls above Groiind). — This is. 

 made in exactly the same manner as previously described fof 

 lime concrete, and the materials are used in the same propor- 

 tions. The only diflference is that cement is used in the place 

 of lime as the binding material, and the rough materials are 

 reduced to a smaller size than for lime concrete. It should be 



