2 BULLETIN 230., U. S. DEPARTMENT OF AGRICULTURE. 



If concrete could be made less absorbent of moisture and less porous, 

 its ability to withstand the penetration of water would be greatly 

 increased, and the material would then be a much more desirable one 

 for structures in which it is now used with only partial success. 



OIL-MIXED CONCRETE. 



While experimenting in the Office of Public Roads in an attempt 

 to develop a nonabsorbent, resilient, and dustless road material, one 

 capable of withstanding the severe shearing and raveling action of 

 automobile traffic, the writer's investigations led him into a very 

 promising discovery. He found that when a heavy mineral residual 

 oil was mixed with Portland cement paste it entirely disappeared in 

 the mixture, and, furthermore, did not separate from the other ingre- 

 dients after the cement had become hard. The possibilities of oil- 

 cement mixtures for waterproofing purposes were recognized, and 

 extensive laboratory tests were immediately begun to determine the 

 physical properties of concrete and mortar containing various quan- 

 tities of oil admixtures. 



These tests have now extended over a period of considerably more 

 than two years. Many valuable data have been obtained, through 

 both laboratory and service tests, which demonstrate very defi- 

 nitely the worth of oil-mixed concrete in damp-proof and waterproof 

 structures. Detailed results of these various tests are given in the 

 appendix. The conclusions so far reached may be summarized briefly 

 as follows : 



It has been shown that the admixture of oil is not detrimental to 

 the tensile strength of mortar composed of 1 part cement and 3 parts 

 sand when the oil added does not exceed 10 per cent of the weight 

 of the cement used. The compressive strength of mortar and of 

 concrete suffers slightly with the addition of oil, although when not 

 to exceed 10 per cent of oil is added the decrease in strength is not 

 serious. Concrete mixed with oil requires a period of time from 50 

 to 100 per cent longer to set hard than does plain concrete, but the 

 increase in strength is nearly as rapid in the oil-mixed material as in 

 the plain concrete. 



Concrete and mortar containing oil admixtures are almost per- 

 fectly nonabsorbent of water and are therefore excellent materials to 

 use in damp-proof construction. The addition of oil, however, does 

 not appear to increase to any great extent the impermeability of con- 

 crete subjected to heavy water pressure, and this method alone will 

 probably not make the concrete proof against the actual percolation 

 of water through the mass. It has been found that strict attention 

 to the details of proportioning, mixing, and placing concrete accom- 

 plishes more toward making it waterproof or impermeable than the 

 addition of any extraneous material. On the other hand, no amount 

 of care in connection with the preparation of concrete prevents the 



