Feasibility of using a lignin-containing waste in asphalt binders

"Published online: 30 January 2019"A lot of water waste streams are produced during the production of hardboard panels. This paper analyses the feasibility of using a lignin-containing waste from the hardboard industry in asphalt binders. It would contribute to both waste reduction and decrease of the consumption of asphalt in order to obtain environmental, economic and social benefits. The waste from the hardboard industry was not subjected to any transformation i.e. it was blended directly with the conventional asphalt. Asphalt binder samples blended with 0, 5, 10, 20 and 40% of the waste were aged in a rolling thin-film oven apparatus. Basic characterisation (penetration grade, ring and ball softening point and resilience) as well as advanced characterisation (dynamic viscosity, shear complex modulus and phase angle) were performed. Asphalt binders blended with up to 20% waste can be stored, pumped and handled at hot-mix asphalt facilities. Addition of the waste to asphalt binder increases the viscosity and the shear complex modulus and reduces the phase angle. The waste produces asphalt binders with higher storage modulus and lower loss tangent. The waste enhances fatigue and rutting resistance. Asphalt binder with 20% of waste displays the best potential for use as an extender and as well as an enhancer in asphalt pavements. The research results can offer technical support to value this waste from hardboard production, without the need for subsequent transformations.(undefined

A hybrid life cycle assessment of public transportation buses with alternative fuel options

Purpose: Alternative fuel options are gaining popularity in the vehicle market. Adopting alternative fuel options for public transportation compared to passenger vehicles contributes exponentially to reductions in transportation-related environmental impacts. Therefore, this study aims to present total air pollutant emissions and water withdrawal impacts through the lifetime of a transit bus with different fuel options. Methods: In consideration of market share and future development trends, diesel, biodiesel, compressed natural gas (CNG), liquefied natural gas (LNG), hybrid (diesel-electric), and battery electric (BE) transit buses are analyzed with an input-output (IO)-based hybrid life cycle assessment (LCA) model. In order to accommodate the sensitivity of total impacts to fuel economy, three commonly used driving cycles are considered: Manhattan, Central Business District (CBD), and Orange County Transit Authority (OCTA). Fuel economy for each of these driving cycles varies over the year with other impacts, so a normal distribution of fuel economy is developed with a Monte Carlo simulation model for each driving cycle and corresponding fuel type. Results and discussion: Impacts from a solar panel (photovoltaic, PV) charging scenario and different grid mix scenarios are evaluated and compared to the nation’s average grid mix impacts from energy generation to accommodate the lifetime electricity needs for the BE transit bus. From these results, it was found that the BE transit bus causes significantly low CO2 emissions than diesel and other alternative fuel options, while some of the driving cycles of the hybrid-powered transit bus cause comparable emissions to BE transit bus. On the other hand, lifetime water withdrawal impacts of the diesel and hybrid options are more feasible compared to other options, since electricity generation and natural gas manufacturing are both heavily dependent on water withdrawal. In addition, the North American Electricity Reliability Corporation’s (NERC) regional electricity grid mix impacts on CO2 emissions and water withdrawal are presented for the BE transit bus. Conclusions: As an addition of current literature, LCA of alternative fuel options was performed in this paper for transit buses with the consideration of a wide variety of environmental indicators. Although the results indicate that BE and hybrid-powered buses have less environmental emissions, the US’s dependency on fossil fuel for electricity generation continues to yield significant lifetime impacts on BE transit bus operation. With respect to water withdrawal impacts, we believe that the adoption of BE transit buses will be faster and more environmentally feasible for some NREC regions than for others