UNIVERSAL PORTLAND CEMENT CO. 
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ditions of weather, and the height of wall accommodated by the 
Time forms at a single filling. Where the work is done by home labor 
^o^BuM occasionally more than 2 weeks are required. The block silo 
Concrete can usually be put up in 4 days to a week, depending upon its 
Silos size and the number of block masons employed. After com- 
pletion it should be allowed to stand at least two weeks before 
filling, to allow the mortar to become firm and hard. Cement stave 
silos are commonly erected complete in 3 days, and cement plaster silos 
in about a week. If the silo is to be filled during the early part of 
September, work on the foundation should be commenced no later than 
August 20th. In all cases the silo should be completed two weeks 
before being subjected to the strain caused by filling. 
Two general methods of concrete construction are available for silo 
work — the monolithic and the concrete block. With the former method, 
^ the materials are hauled to the site of the silo and there mixed 
Comparison placed within forms; the latter method requires that the 
of the block be made and cured in some convenient place, and later 
Monolithic hauled to the site to be laid up in the wall. 
Block Types Each method has certain advantages and disadvantages, 
but the matter of personal choice generally influences the decision 
to build either with monolithic walls or with block. The monolithic silo 
is generally the easier of the two for inexperienced persons to build, and is 
usually a little cheaper than the block, as it does not require the service of 
good masons or the use of a block machine; the block silo, however, makes 
the use of forms unnecessary, produces a wall with continuous vertical 
air spaces, and slightly reduces the amount of materials used. 
