72 Concrete Silos 



When the forms have been filled for the day do not 

 smooth the top with a trowel, but leave it as rough as 

 possible. A good plan is to roughen the top surface 

 just as the concrete starts to set. Before putting fresh 

 concrete on this wall the next day, the top surface 

 should be soaked with water 'and then sprinkled with 

 raw cement, which will help in making a good union 

 between courses. The forms must not be removed for 

 at least 5 hours after filling. 



A brush coat of cement wash may be applied as 

 soon as the form is raised and before the wall has had a 

 chance to dry. This coat of cement helps to make the 

 wall less porous and therefore more nearly air and 

 water tight. The wash is prepared by mixing together 

 cement and water to the consistency of thick lime 

 whitewash, and is applied with a whitewash brush in 

 the ordinary way. If the wall has had time to dry it 

 should first be drenched with water. 



After this coat of cement wash has been applied the 

 whole interior may be painted with coal tar thinned 

 with gasoline. The coal tar makes the wall impervious 

 and also protects it from the action of acids which 

 develop in the silage. It should be renewed from year 

 to year as may be required. The application of the 

 coal tar may be left until the wall is complete, but 

 should be done before removing the interior scaffold. 



