CHAPTER III 



How CONCRETE MEETS THE REQUIREMENTS 



Having pointed out in Chapter II the standards of 

 efficiency by which any silo must be judged, it is of 

 interest to note how completely concrete as a building 

 material fulfills all these requirements. 



Concrete can, in the first place, be made both air- 

 tight and moisture proof. It is well known that the 

 composition of concrete can be governed to suit the 

 particular requirements in any case. If it is desired 

 to make it impervious to both air and moisture, it is 

 only necessary to so proportion the various sizes of 

 aggregates and so regulate the amount of cement that 

 dense and impervious concrete will result. 



If it is desirable to further insure the non-porous 

 nature of the concrete, it may have added to it some 

 other ingredient for making it still more dense. There 

 are >a large number of such products on the market, 

 perhaps most of which will answer very well the pur- 

 pose for which they are intended. 



The same result can also be attained by giving the 

 concrete a surface treatment, either of a cement wash 

 or of some proprietary pore-filling compound. There 

 are also a number of these on the market, some of 

 which have a bituminous or asphaltic base and could 

 be used only on the interior walls, while others have a 

 pleasing appearance, or are absolutely colorless, and 

 could be used exteriorly. 



It is generally conceded that concrete itself can, 

 if given proper attention, be made sufficiently dense 



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