Disposing used engine oils in concrete – Optimum dosage and compatibility with water reducers

• Control of undesirable air content and oily smell resulting from the addition of UEO.
• Maximum UEO dosage beyond which detrimental effects on concrete properties can be encountered.
• Compatibility between UEO and commercially available water reducers.
• Timing addition of UEO during concrete batching sequence.

Used engine oils (UEOs) are among the toxic wastes that affect marine and human lives. A comprehensive research project was undertaken to address relevant implications that would result from disposing synthetic or mineral UEO on concrete performance. These include the optimum dosage rate, compatibility with conventional water reducers (WRs), timing addition during the batching sequence, and control of undesirable increase in air content and oily smell of concrete.Test results have shown that the excessive increase in fresh air content and oily smell released during concrete batching due to the addition of UEO can be controlled by the incorporation of small quantities of defoaming and odorant chemicals. An optimum UEO dosage of 0.3% of cement mass was found, beyond which detrimental effects on initial slump, setting time, and compressive strength can be encountered. The incorporation of UEO together with conventional WR in concrete resulted in a certain incompatibility reflected by increased viscosity and rates of slump loss over time. Such incompatibility was particularly accentuated when the UEO was added before the WR during the batching sequence.