Abstract
The quest for improvement in service life and performance of road pavement via reduction of oxidative aging failure of bitumen, led us to the investigation of novel application of Silver nanoparticles (AgNPs) as potential anti-oxidative material for Agbabu natural bitumen (ANB). The raw ANB was purified to form the base and the base modified in a stainless reactor using AgNPs via melt blend technique at temperature of 120 °C under stirring at 1200rpm. The proportions of AgNPs used for the modification were 1.5, 3.0 and 4.5 wt% and long-term aging was thermally simulated on the base and modified base samples at 60 °C. The aged samples were then subjected to Fourier Transform Infrared (FTIR) Spectroscopic Analysis to study the changes in the size of the peaks of the oxidation-related compounds. Physical and flow parameters (PFPs) of the base and modified base samples were characterized using softening point temperature, kinematic viscosity, penetration index, flash and fire points, penetration, kinematic viscosity and Oscillatory disc Rheometer (ODR) test. FTIR analysis showed that the AgNPs incorporation into ANB at 1797 cm−1, 1217 cm−1, 1300 cm−1 and 1097 cm−1 in the spectrum of the base sample. The sulphoxide peaks at 1031 cm−1 was completely obliterated. There was progressive reduction in the area of the carbonyl peak at 1693 cm−1 implying progressive lowering of the carbonyl index value with increasing in the amount of AgNPs used in the modification. These changes are attributable to the anti-oxidative potential of the AgNPs. The mechanism of the anti-oxidative effect of AgNPs is proposed to be due to scavenging of the free radical produced in the oxidation process. The values of softening point temperature, kinematic viscosity, penetration index, and flash and fire points increased while that of penetration and specific gravity reduced as the quantity of AgNPs in the base increased. The ODR test showed that, the modified samples compared to base sample at lower and higher road pavement temperatures are less prone to fatigue cracking and rutting, respectively. Thus, this study provides preliminary information about the novelty of AgNPs as potential antioxidant for improving the durability/performance of bitumen in pavements.
Highlights
Rapid deterioration of bitumen pavements which reduces bitumen service life as binder is often caused by oxidative aging [1]
During storage, mixing, laying and transportation processes of bituminous mixture, bitumen was exposed to undesirable rapid aging, but slow aging process occurs during the service life of bitumen in pavement [1, 2]
The significance of this is to improve the durability of the bitumen in pavement
Summary
Rapid deterioration of bitumen pavements which reduces bitumen service life as binder is often caused by oxidative aging [1]. They study the biodegradation of hydrocarbon compounds in the ANB and reported a reduction in total aliphatic and poly aromatic contents as a result of its (ANB) vulnerability to biodegradation by some bacteria strains It has been documented in literature that FTIR spectrometry can be successfully used for the identification and quantification of the effects of modifiers on the aging of bitumen as well as for the evaluation of their effects on chemical and physical properties of asphalt [2, 17, 27]. The use of FTIR analysis to investigate the anti-oxidative ability of AgNPs on base in a simulated long term aging under artificial condition with an oven at 60 C [17], the effects of AgNPs anti-aging on the physical and flow properties and the study of the type of their interactions were the objectives of this study This application may be compared with the other existing nanoparticles currently being used. This study is meant to contribute to knowledge on the novelty of anti-oxidative ability of AgNPs for the modification of bitumen for pavement applications
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