10 BULLETIN 230, U. S. DEPARTMENT OF AGRICULTURE. 
with the mortar or concrete used in construction: Basement floors, 
basement walls, watering troughs, cisterns, barns, silos, irrigating 
canals, the concrete base for bituminous concrete and asphalt road- 
ways, concrete blocks, roofs, stucco, and numerous important engi- 
neering constructions. 
BASEMENT FLOORS. 
A basement floor which will remain perfectly dry may be con- 
structed at a cost but very slightly higher than that of the ordinary 
basement floor by the incorporation of a petroleum residuum oil 
with the ordinary concrete mixture. The following method of con- 
struction, using an oil-cement mixture, is suggested as one which 
will prevent the permeation of moisture even from a very wet subsoil. 
It will be well, if the underlying soil is very wet, to lay a 6-inch 
foundation of sand, cinders, broken stone, or gravel, compacting 
these materials well by tamping. In addition, it will be of advantage 
to employ drain tiles in this porous foundation, leading them to a 
sewer if possible. On top of the foundations should be laid a 4-inch 
layer of concrete mixed in the proportions of 1 part of Portland 
cement, 2\ parts of sand, and 5 parts of broken stone or gravel. 
Before the concrete base has hardened, a top or wearing coat of mortar 
mixed in the proportions of 1 part of cement and 2 parts of sand or 
stone screenings, and containing 5 per cent of oil (2| quarts per bag 
of cement) should be laid. This top coat, because of its nonabsorbent 
character, will give perfect protection from underlying moisture, and 
moreover it will build a floor which will dry out very quickly after 
washing, since practically none of the washing water will be absorbed. 
It might be thought that the addition of oil to the mortar wearing 
coat would tend to make the surface slippery. Such, however, is not 
the case; nor is the appearance very much different from that of an 
ordinary cement floor. Should joints be provided for expansion and 
contraction, it will be necessary to fill them with a good bituminous 
filler to prevent the entrance of water. 
Many cellar floors now made of Portland cement concrete are 
giving trouble owing to the permeating moisture; They are con- 
tinually damp and, owing in part to the constant evaporation from 
their surface, they are cold. Such a condition may be remedied by 
the application of an oil-mixed mortar coat to the surface of the old 
floor. Before attempting to lay the new wearing surface, the old 
floor should be scrubbed thoroughly clean and should be made 
thoroughly wet. The bond between the old and the new work will 
be improved if the old surface be roughened with a stone hammer. 
A wash composed of 1 part of hydrochloric acid and 5 parts of water 
may be used to clean the surface. This will dissolve some of the 
cement from the old work, leaving the aggregate exposed. The acid 
