Laboratory Comparison of In-Situ, Ex-Situ and Laboratory Produced Foamed Bitumen Stabilized Base

Foamed bitumen stabilisation of granular base course materials is well established as a beneficial technology for the improvement of existing materials and for expedient pavement construction or rehabilitation. Foamed bitumen base (FBB) can be produced in-situ, by a specialised stabilizing train, or ex-situ, in a pugmil. It is most common for existing pavements to be stabilized in-situ while new materials are usually stabilized ex-situ. However, this is not always the case and regardless of the field production method, FBB is usually characterized and designed using material produced in a small laboratory mixer. Consequently, an objective comparison of the three production methods is warranted. This research produced otherwise nominally identical FBB using laboratory, in-situ and ex-situ processes and identified significant differences in the resulting material properties and the achieved modulus. Further research should focus on adjusting laboratory production protocols to ensure that field production conditions are adequately represented by common laboratory mixture design processes.