Plain Concrete for Farm Use

John Stuart Mill · en
It is necessary to exercise great care in the placing of the concrete.
Where practicable, the structure or object should be poured in one
operation to avoid leaky joints, but when this is not possible
precautions should be taken to secure a tight joint between concrete of
different ages. The surface of concrete which has set must be cleaned of
dirt and scum down to the true concrete. This surface then should be well
whetted and painted immediately with a creamy mixture of cement and water
before placing the new concrete. A good plan, when discontinuing work on
structures intended to hold liquids, is to embed a 6 or 8 inch strip of
tin or thin sheet metal to half its width in the concrete so that the
other half will project into the new concrete.

A wall thick enough to resist the stresses put upon it will generally
resist percolation of water, but 6 inches may be considered as a minimum.

Contraction and expansion must be controlled to avoid the occurrence of
leaks. To guard against cracks due to unequal settlement or other causes,
most concrete designed for water-tightness should be reinforced. In some
mass work, special contraction joints, as described on page 23 may be
necessary. Rules for the use of reinforcement and contraction joints can
not be given, as the requirements in each case vary with the conditions
to be met.


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                           ORGANIZATION OF THE
                 UNITED STATES DEPARTMENT OF AGRICULTURE

                            October 21, 1929