FARM EQUIPMENT 
41 
being built of concrete. This is almost a concrete age. 
Various materials are used for making concrete. Port¬ 
land cement is the basis of the solidifying element. Sand, 
gravel, crushed stone, and ballast make up the general 
body of a concrete structure. These materials are mixed, 
while the cement is fresh, with water in varying propor¬ 
tions. This mixture should be placed in the mold before 
it has time to “set” or become hard. It is desirable to 
Fig. 28.—A brooder coop and p' chicks. 
pack the concrete well into the form while it is fresh. 
Pounding down with a tamping stick causes the mixture 
to make a uniform mass. 
The strength of concrete varies with the manner of 
making up the cement, stone and water. “Grouting” is 
the term applied to concrete for filling in roads, walks 
or floors. A thin mortar made of two parts sand and one 
part cement, poured over larger rocks and brickbats 
makes a good “grouting.” Foundation concrete is made 
