The effects of hydrocarbon contamination on concrete strength

The development of brownfield sites often requires foundation concrete to be placed in contact with soils contaminated with hydrocarbons. There is a common perception that the hydrocarbons affect the setting and hardening of the concrete, giving a reduced long-term strength. There is however limited quantitative data to support this view. Laboratory testing of concrete cubes cured in various hydrocarbon compounds has been undertaken. The results indicate that hydrocarbons do reduce the long-term strength gain of concrete by up to 25%. This can be allowed for in design, thus avoiding the need for expensive sleeving or surface protection systems. Available evidence suggests that the effects of petroleum hydrocarbons on hardened concrete, which has achieved its design strength, are of limited concern. Creosote, however, can affect hardened concrete that has achieved its design strength. Where hardened concrete is likely to come into contact with creosote derived contamination then again a reduction in long-term strength should be considered.