Potential detrimental effects of bacterial activity on bitumen

This study was conducted to validate the hypothesis that one of the detrimental influences on bituminous pavements is the negative impact of specific bacterial species. To achieve this objective, the bacteria present within bituminous mixtures were isolated, followed by an examination of their phenotypic attributes and their capacity to degrade bitumen. Among 24 bacterial isolates, five predominant isolates exhibiting characteristic phenotypic features and significant destructive potential were identified through polymerase chain reaction (PCR) and named Stutzerimonas sp., Brevundimonas aurantiaca, Bacillus sp., Stutzerimonas stutzeri, and Pseudomonas aeruginosa. The destructive impacts of these target bacteria on the properties of bitumen were assessed employing various methodologies including scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), contact angle (CA), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). The results showed that the bacteria caused aging and reduced adhesion by changing the surface texture, increasing C=O and S=O functional groups, and decreasing hydrophobicity. They also cause a change in the molecular structure of bitumen, a decrease in molecular weight dispersion, and an increase in heat capacity, which indicate the negative effects of bitumen aging. In fact, bacteria in bituminous environments can cause bacterial aging of bitumen and cause various damages in the environment in the end.