Assessment of microbial degradation of various types of bitumen using FTIR

Pseudomonas aeruginosa (P. aeruginosa), a common bacterium found in the environment, is known to be a potential cause of bitumen degradation. Hence, the effect of P. aeruginosa on bitumen is to be evaluated. For this purpose, Reclaimed Asphalt Pavement (RAP) is collected from the pavement surface and it is tested for the presence of P. aeruginosa. Subsequently, this isolated P. aeruginosa strain is employed in experiments to evaluate its effect on three types of bitumen, namely: Viscosity Grade-30 (VG-30), and two types of Polymer Modified Binders (PMBs) viz., PMB-K and PMB-T. Bitumen degradation, Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM) studies show that P. aeruginosa has degraded PMB-T more than PMB-K and VG-30. Degradation occurs due to the breakage of bonds between polymer and bitumen and confirmed that P. aeruginosa has the ability to degrade PMBs, which may alter their physical properties. The degradation test results presented that PMB-T has 12.5% degradation compared to the control sample. The FTIR findings indicate that P. aeruginosa has modified the chemical composition of PMBs, and has converted them into base bitumen. It is recommended to study, molecular analyses (i.e. metagenomic and transcriptomic) of P. aeruginosa on PMBs.