Use of Offshore Drilling Waste in Hot Mix Asphalt (HMA) Concrete as Aggregate Replacement

Despite continuous research and development on drilling fluids and waste minimization during the last 40 years, offshore drilling waste (OSDW) remains a significant environmental concern for the petroleum industry. OSDW contains three types of contaminants namely, heavy metals from drilling fluid, oil from oil based mud or petroleum contamination and naturally occurring radioactive substances from exposed formations. In this study a promising and permanent solution based on recycling of OSDW as road construction materials has been investigated. It has been revealed previously that five to ten percent of some waste materials such as recycled asphalt pavement, tire rubber, glass, roofing shingles, polythene etc. can be added to hot mix asphalt (HMA) concrete without sacrificing its strength and performance. These wastes can be added to the HMA by either replacing the mineral filler or proportionately reducing the amount of virgin material in the original mix. In this laboratory test study, different percentages of OSDW were added as aggregate replacement and the properties of resulting blends were evaluated. Three beneficial actions, namely, incineration, dilution and solidification took place. At the end, the effectiveness of using OSDW was determined with the Marshall stability and flow, permeability of HMA concrete, leachability and resilient modulus. It has been found that for the drilling waste used in this research the percentage that can be used in HMA concrete without sacrificing its properties is as high as 20%. Even though the percentage of waste that can be used as aggregate replacement varies with waste types and properties, the proposed technique offers significant promises for OSDW recycling.