Q: Does exposure to petroleum-based lubricating oils and transmission fluids cause concrete floors to disintegrate?
A.: Pure mineral oils such as gasoline, fuel oils, lubricating oils, and petroleum distillates reportedly don't attack mature concrete (Refs. 1 and 2). However, a book published in 1950 (Ref. 3) says that lubricating oils are often improved by adding fatty oils (animal and vegetable oils). These oils can decompose to form fatty acid, which disintegrates concrete. We don't know whether modern lubricating oils contain fatty oils, but they do contain additives that improve the performance of refined-petroleum base stocks. We don't have any information on the effects of such additives on concrete.
It's also known that used lubricating oils have higher levels of acidity because of oxidation. However, the references cited don't address the effects of used oils vs. virgin oils. Because of their increased acidity, it's possible that used oils might attack mature concrete. But if that's the case, you'd expect to find a lot of deteriorating, oil-stained garage floors. Have any of our readers seen evidence of concrete deterioration in industrial floors repeatedly exposed to oil spills?
- F.M. Lea, The Chemistry of Cement and Concrete, 3rd ed., Chemical Publishing Co. Inc., New York, 1971, p. 660.
- Sandor Popovics, "Chemical Resistance of Portland Cement Mortar and Concrete," Corrosion and Chemical Resistant Masonry Materials Handbook, Noyes Publications, Park Ridge, N.J., 1986, p. 336.
- A. Kleinlogel, Influences on Concrete, Frederick Ungar Publishing Co., New York, 1950, pp. 91-93.
In the March 1997 Problem Clinic (pp.314-315), a reader wanted to know if exposure to petroleum products causes concrete floors to deteriorate. I have some experience that may provide a partial answer. I am a specialist concrete building engineer and was retained to investigate severe concrete deterioration of reinforced-concrete foundations, piers and beams under a paper machine at a plant in British Columbia. The concrete had been placed in the late 1920s and may have used aggregates from a saltwater source. Throughout the years, lubricating oils from the machinery spilled over certain parts of the concrete, resulting in the deterioration, which had progressed several inches into the concrete. The concrete away from the oil exposure showed no signs of breakdown and was of good quality, with core strengths of about 3000 psi.
Thus, in this case, we know lubricating oils were the main contributor to the concrete deterioration. Conjecture is that the lubricating oils of bygone years (and perhaps the present) contain sufficient sulfur, which over time converted to acid in the alkaline concrete. At another plant I investigated, where diesel injectors were being remanufactured, the concrete floor had extensively deteriorated in areas where diesel oil had been spilling continuously for about 20 years. The deterioration was due to chemical attack by the oil.
- G.W. Spratt, Gordon Spratt & Associates Ltd., Vancouver, British Columbia