GC-MS IDENTIFICATION OF BIOMARKERS IN ROAD ASPHALTS AND IN THEIR PARENT CRUDE OILS - RELATIONSHIPS BETWEEN CRUDE-OIL MATURITY AND ASPHALT REACTIVITY TOWARDS WEATHERING

Asphalt cements (vacuum residues of petroleum) used as binders for roa d construction can undergo weathering phenomena or natural oxidation t o various degrees depending on their chemical structures and on their origin. The first aim of this study was to determine the characteristi cs of the source rocks generating the parent crude oils. The second ai m was to correlate the chemical structures of recovered asphalt cement s to the genesis data of their parent crude oils in order to predict t heir sensitivity towards weathering. Towards these ends, saturated fra ctions of sixteen asphalt cements and their parent crude oils have bee n analysed by GC-MS (SIR). Many linear, branched and naphthenic compou nds from the saturated hydrocarbon fraction have been identified. Hopa nes (m/z = 191), norhopanes (m/z = 177, 163) and steranes (m/z = 217 a nd 218) have been selected to characterize original and weathered asph alts as well as their parent crude oils. Using geochemical indices (T- s/T-s + T-m, %C-29 steranes, etc.), aliphatic structures of the asphal ts and corresponding crude oils could be differentiated through princi pal component analysis (PCA). The selected variables involve geochemic al indices and asphalt rheological characteristics. Results are in goo d agreement with the classification obtained from FTIR indices (linear alkanes, branched aliphatics, aliphatics versus aromatic structures, etc.). Moreover, good correlations in geochemical indices have been fo und between asphalts and their parent crude oils. Finally, it was also possible to predict some rheological properties (e.g., stiffness at l ow temperature) using a multilinear regression which involves geochemi cal indices of parent crude oils before any physical transformation (d istillation, etc.) and FTIR indices of corresponding asphalt cements. Copyright (C) 1996 Elsevier Science Ltd.