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 



