154 ADVANTAGES OF CONCRETE ON FARMS 



ture one and one-half barrels ; medium mixture one and 

 one- fourth barrels ; ordinary mixture one and one-eighth 

 barrels ; lean mixture seven-eighths of a barrel. 



In construction work such as floors, barns, fence posts, 

 bridges, reinforcements of iron are absolutely necessary. 

 The beginner will need the supervision of an expert in 

 using reinforcements. 



Measure exact amounts for each part. Mix thor- 

 oughly and not too long before applying the water. 

 Cement will set in 20 or 30 minutes and if disturbed after 

 that loses its strength. 



Spread the sand and cement on a mixing board and 

 mix thoroughly, adding enough water when mixed to 

 bring the mixture to the consistency of mortar. 



Add the proper quantity of crushed rock and mix all 

 together, after which it is ready for use. In this manner 

 the sand grains are all covered with the finer particles of 

 cement and the crushed rock when added has all the 

 voids filled with temperate mixture. This undoubtedly 

 gives the greatest strength for materials used. 



A very common method, however, is to mix all three 

 parts at once while yet dry and then to mix with water 

 until the mixture will pack well, and handle with a 

 shovel. 



Get the form walls rigid and do not use lumber that is 

 too dry, as it takes up moisture and changes its shape so 

 as to injure the concrete in setting. 



Do not allow concrete work to dry out fast, as cracks 

 will appear. It should be protected from the sun for 

 three or five days and sprinkled with water to insure even 

 setting throughout the concrete. 



In two weeks concrete gains strength sufficient for ordi- 

 nary use, but 60 days should elapse before it is given a 

 full load. 



