Quantification of physicochemical properties, activation energy, and temperature susceptibility of foamed asphalt binders

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© 2017 Applications of foamed binder have been spurred by the increased focus on sustainable construction approach and stringent environmental laws. This study was initiated to evaluate the performance of foamed asphalt binder produced using a combination of physical and chemical foaming agents, known as ethanol and sodium bicarbonate (NaHCO3), respectively. This paper presents the properties of foamed asphalt binder assessed using Fourier transform infra-red (FTIR) spectroscopy, asphalt binder cracking device (ABCD), and activation energy analysis. The FTIR test was conducted to evaluate the possibility of any chemical reaction taken place, as well as to characterize the effects of oxidation on the chemical functional groups present in foamed asphalt binders. The ABCD test was carried out to evaluate the thermal cracking temperatures of prepared binders. The activation energy of each binder type was analyzed based on the viscosity test results and Arrhenius equation to estimate the energy required to overcome the intermolecular forces between the molecules in the asphalt binder to initiate flow. The FTIR results reveal that ethanol alone is unreactive with the binder, where most of the functional groups have shown comparable change ratios. This indicates that there are no chemical reactions that occurred in the foamed asphalt binders, either with the addition of ethanol or various combinations of ethanol and NaHCO3. The application of foaming agents definitely lowers the activation energy to overcome the intermolecular forces between the molecules in the asphalt binder to allow flow to occur. The foamed binders were found to have a comparable or better low temperature characteristic as compared to the control binder. A higher dosage of foaming agents proportionally increased the resistance to thermal cracking of asphalt binders. Overall, the use of foaming technique and newly proposed foaming agents has shown great potential to produce eco-friendly pavement material.

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Construction and Building Materials