94 SILOS: CONSTRUCTION AND SERVICE 



Blocks for Silos. In silo construction we have two 

 reasons for specifying hard-burned brick; one is that it must 

 not absorb a great amount of moisture from the silage; 

 another is that if soft or porous brick are exposed to the 

 weather they are not durable, as moisture freezing in the pores 

 of the brick expands and causes the block to disintegrate. 

 This has been noticed by every one in the case of soft drain 

 tile which have been allowed to lie in a slough over winter. 



In order to make sure that brick or clay blocks are right 

 for silos it is necessary to buy only such brick or blocks as will 

 absorb an average of 5 per cent or less of their weight of 

 moisture. No block should be used that absorbs over 8 per 

 cent. If this quality is secured the result will be a good 

 durable silo, if it is put together with other good material by 

 a good workman. 



In addition to this, it should be specified that all blocks 

 fit the circle within Y% of an inch. When ordering blocks it 

 should be borne in mind that uniform color of blocks is quite 

 desirable and greatly increases the appearance of the 

 building. 



Absorption Test. A convenient method of determining 

 the amount of water these products will absorb is either to 

 take the blocks hot from the kiln or place them in an oven 

 where they will have a temperature higher than boiling water 

 continually for two days. Then they should be weighed and 

 placed in water for a couple of hours or until they cease to 

 increase in weight. The increase in weight divided by the 

 dry weight gives the percentage of the absorption. 



This same test will indicate whether or not there are lime 

 nodules in the clay. Sometimes pebbles of limestone occur in 

 the clay, which, when the clay is burned, become quicklime, 

 and this exerts a swelling force when it comes in contact with 

 water. This force is such as to chip off or split the material. 



