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| 2. |
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| 3. |
- Butt, Ali Azhar, 1984-, et al.
(author)
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Assessment of the attributes based life cycle assessment framework for road projects
- 2015
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In: Structure and Infrastructure Engineering. - : Taylor & Francis. - 1573-2479 .- 1744-8980.
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Journal article (peer-reviewed)abstract
- Number of life cycle assessment (LCA) tools has been suggested for pavements. However, very few have been adopted by the road authorities. Key reasons for this lack of implementation have been the tendency for very broad LCA analyses that include system boundaries considerably beyond the more natural system boundaries associated with road design, construction and maintenance as well as the lack of available LCA tools that have attributes that reflect key road properties. In this paper, a new attributesbased pavement LCA framework is evaluated for use on real road materials. Aggregates from two different sources and the effect of using a warm mix asphalt additive (WMAA) in asphalt mixtures were investigated in the laboratory. Different pavement design alternatives were generated using the laboratory data and analyzed using the road LCA framework. Asphalt production and material transportation were found to be the most energy consuming processes. The results presented showed that having actual pavement material properties as the key attributes in LCA enables a pavement focused assessment of environmental impacts associated with different design options and, LCA can help in decision support by evaluating environmental impacts of different design alternatives in a project planning/design stage.
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| 4. |
- Butt, Ali Azhar, 1984-, et al.
(author)
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Bitumen Feedstock Energy and Electricity Production in Pavement LCA
- 2012
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Conference paper (peer-reviewed)abstract
- Asphalt production consumes considerable amount of fuel and electric energy as significant amount of materials (bitumen and aggregates) are blended together for the construction of flexible pavements. Bitumen is used in asphalt as a binder but can also be used as an alternate energy source. Feedstock energy of bitumen becomes relevant in the life cycle cost (LCC) study, as cost of the binder would be reflected in its alternative value as fuel. In this study, a method was suggested to calculate energy content of the bitumen. Importance of choosing electricity not produced in local diesel generators was also demonstrated. Replacing fuel with inefficiently produced electricity for heating the materials in the asphalt plant would result in high environmental impacts. The calculation of feedstock energy and the understanding of efficient energy production and use could be utilized in the life cycle assessment (LCA) of the roads.
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| 5. |
- Butt, Ali Azhar, 1984-, et al.
(author)
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Considering the benefits of asphalt modification using a new technical LCA framework
- 2016
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In: Journal of Civil Engineering and Management. - : Taylor & Francis. - 1392-3730 .- 1822-3605. ; 22:5, s. 597-607
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Journal article (peer-reviewed)abstract
- Asphalt mixtures properties can be enhanced by modifying it with additives. Even though the immediatebenefits of using polymers and waxes to modify the binder properties are rather well documented, the effects of suchmodification over the lifetime of a road are seldom considered. To investigate this, a newly developed open technical lifecycle assessment (LCA) framework was used to determine production energy and emission limits for the asphaltadditives. The LCA framework is coupled to a calibrated mechanics based computational framework that predicts the intimepavement performance. Limits for production energy of wax and polymers were determined for the hypotheticalcase studies to show how LCA tools can assist the additives manufacturers to modify their production procedures andhelp road authorities in setting ‘green’ limits to get a real benefit from the additives over the lifetime of a road. From thedetailed case-studies, it was concluded that better understanding of materials will lead to enhanced pavement design andcould help in the overall reduction of energy usage and emissions.
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| 6. |
- Butt, Ali Azhar, et al.
(author)
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Environmental friendly wax modified mastic asphalt
- 2009
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Conference paper (peer-reviewed)abstract
- Mastic asphalt products (Gussasphalt) require high working temperatures, and harder requirements concerning bitumen fumes and carbon dioxide emissions. Consequently, the need of a new means of producing and placing mastic asphalt at lower temperatures is particularly large. One way of reducing asphalt mixture temperature is by using special flow improving additives like wax. This technique has successively been tried for polymer modified mastic asphalt used for bridge decks and parking areas in Sweden. However, there still are uncertainties about possible negative impact on crack susceptibility at lower temperatures due to wax additives.In this study, 4% montan wax (Asphaltan A) was used for one particular polymer modified mastic asphalt product. Type and amount of wax additive was selected based on results from earlier studies. The impact on binder, binder/filler mixtures and mastic asphalt from production was tested in the laboratory, focusing on low temperature performance. The bending beam rheometer (BBR) was used for determining low temperature creep compliance and the tensile stress restrained specimen test (TSRST) for determining fracture temperatures. Binder properties were determined using dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) spectroscopy and conventional tests (softening point, penetration, elastic recovery, breaking point, viscosity and storage stability). Aging was performed using the rolling thin film oven test (RTFOT) at 200°C.As expected, the addition of wax to the polymer modified binder showed a viscosity reduction at higher temperatures, corresponding to a similar positive effect of more than 10°C on production and laying temperature for the mastic asphalt. DMA and BBR results showed some increase in stiffness and a more elastic response of the wax modified binder at medium and low temperatures. The TSRST fracture temperature was 5 °C higher for the mastic asphalt containing wax, indicating however no dramatic negative impact on crack susceptibility.
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| 8. |
- Butt, Ali Azhar, 1984-, et al.
(author)
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Importance of systems approach for evaluating the life cycle environmental impacts of a road project
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Other publication (other academic/artistic)abstract
- Aggregates from two different sources and the effect of using a warm mix asphalt additive(WMAA) in asphalt mixtures were investigated in the laboratory. Different pavement designalternatives were generated using the laboratory data and analysed using a road life cycleassessment (LCA) framework. It was concluded that the effects of WMAAs must beevaluated on a case by case basis since WMAA interaction with the aggregate surfacemineralogy appears to play a significant role. Asphalt production and material transportationwere found to be the most energy consuming processes having high greenhouse gasemissions. The results presented also showed that having actual pavement material propertiesas the key attributes in LCA enables a pavement focused assessment of environmental costsassociated with different design options.
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| 9. |
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| 10. |
- Butt, Ali Azhar, et al.
(author)
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Life Cycle Assessment for the GreenProcurement of Roads : A Way Forward
- 2015
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In: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 90, s. 163-170
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Research review (peer-reviewed)abstract
- Life cycle assessment (LCA) methodology can be used to assess the environmental impacts of a road system over its entire life time. However, it is very important to align the potentials and limitations of such tools with their intended purpose. For the LCA to be useful for the decision support in a procurement situation, it should therefore be important to have a clear understanding of the technical features (attributes) that build up the life cycle phases. In this paper, different types of decisions situations are outlined based on at what level of complexity (network or specific project) and at what stage within the planning process (early planning or late planning/design) the decision is to be made, and relevant methodological choices for these decision situations are discussed. Further, the attributes that are important to consider in an asphalt road LCA that seeks to serve as a decision support in a procurement situation are suggested and technical features for these attributes are outlined with focus on Energy and GreenHouse Gas emissions. It can be concluded that in order to aid the implementation of green procurement, it would help if the attributes of the system are defined in a transparent manner and consistently calculated. It is, however, also important that the attributes should mirror the material properties used in a pavement design and therefore be closely linked to the performance of the road in its life time. It is also recommended to report the feedstock energy in the road LCAs.
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| 11. |
- Butt, Ali Azhar, 1984-, et al.
(author)
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Life Cycle Assessment Framework for Asphalt Pavements : Methods to Calculate and Allocate Energy of Binder and Additives
- 2014
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In: The international journal of pavement engineering. - : Informa UK Limited. - 1029-8436 .- 1477-268X. ; 15:4, s. 290-302
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Journal article (peer-reviewed)abstract
- The construction, maintenance and disposal of asphalt pavements may lead to considerable environmental impacts, in terms of energy use and emissions during the life of the pavement. In order to enable quantification of the potential environmental impacts due to construction, maintenance and disposal of roads, an open life cycle assessment (LCA) framework for the asphalt pavements is presented in this paper. Emphasis was placed on the calculation and allocation of energy used for binder and additives at the project level. It was concluded from this study that when progressing from LCA to its corresponding life cycle cost, the feedstock energy of the binder becomes highly relevant as the cost of the binder will be reflected in its alternative value as fuel. Regarding additives like wax, a framework for energy allocation was suggested. The suggested project level LCA framework was demonstrated in a limited case study of a Swedish asphalt pavement. It was concluded that the asphalt production and transporting materials were the two most energy-consuming processes, emitting most greenhouse gases depending on the fuel type and electricity mix.
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| 12. |
- Butt, Ali Azhar, 1984-
(author)
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Life Cycle Assessment of Asphalt Pavements including the Feedstock Energy and Asphalt Additives
- 2012
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Licentiate thesis (other academic/artistic)abstract
- Roads are assets to the society and an integral component in the development of a nation’s infrastructure. To build and maintain roads; considerable amounts of materials are required which consume quite an amount of electrical and thermal energy for production, processing and laying. The resources (materials and the sources of energy) should be utilized efficiently to avoid wastes and higher costs in terms of the currency and the environment.In order to enable quantification of the potential environmental impacts due to the construction, maintenance and disposal of roads, an open life cycle assessment (LCA) framework for asphalt pavements was developed. Emphasis was given on the calculation and allocation of energy used for the binder and the additives. Asphalt mixtures properties can be enhanced against rutting and cracking by modifying the binder with additives. Even though the immediate benefits of using additives such as polymers and waxes to modify the binder properties are rather well documented, the effects of such modification over the lifetime of a road are seldom considered. A method for calculating energy allocation in additives was suggested. The different choices regarding both the framework design and the case specific system boundaries were done in cooperation with the asphalt industry and the construction companies in order to increase the relevance and the quality of the assessment.Case-studies were performed to demonstrate the use of the LCA framework. The suggested LCA framework was demonstrated in a limited case study (A) of a typical Swedish asphalt pavement. Sensitivity analyses were also done to show the effect and the importance of the transport distances and the use of efficiently produced electricity mix. It was concluded that the asphalt production and materials transportation were the two most energy consuming processes that also emit the most GreenHouse Gases (GHG’s). The GHG’s, however, are largely depending on the fuel type and the electricity mix. It was also concluded that when progressing from LCA to its corresponding life cycle cost (LCC) the feedstock energy of the binder becomes highly relevant as the cost of the binder will be reflected in its alternative value as fuel. LCA studies can help to develop the long term perspective, linking performance to minimizing the overall energy consumption, use of resources and emissions. To demonstrate this, the newly developed open LCA framework was used for an unmodified and polymer modified asphalt pavement (Case study B). It was shown how polymer modification for improved performance affects the energy consumption and emissions during the life cycle of a road. From the case study (C) it was concluded that using bitumen with self-healing capacity can lead to a significant reduction in the GHG emissions and the energy usage. Furthermore, it was concluded that better understanding of the binder would lead to better optimized pavement design and thereby to reduced energy consumption and emissions. Production energy limits for the wax and polymer were determined which can assist the additives manufacturers to modify their production procedures and help road authorities in setting ‘green’ limits to get a real benefit from the additives over the lifetime of a road.
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| 13. |
- Butt, Ali Azhar, 1984-
(author)
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Life Cycle Assessment of Asphalt Roads : Decision Support at the Project Level
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Transport infrastructures such as roads are assets for the society as they not only ensure mobility but also strengthen society’s economy. Considerable amount of energy and materials, that include bitumen, aggregates and asphalt, are required to build and maintain roads. Improper utilization of energy and/or use of materials may lead to more waste and higher costs. The impact on the environment cannot be neglected either. Life cycle assessment (LCA) as a method can be used to assess the environmental impacts of a road system over its entire life time. Studying the life cycle perspective of roads can help us improve the technology in order to achieve a system that has a lower impact on the environment. There are number of LCA tools available. However, implementation of such tools is still unseen in real road projects. This clearly indicates that there are gaps which are needed to be filled in order to bring these tools into practice. An open road LCA framework was developed for the asphalt roads in order to help in decision support at the late project planning stage such as that related to the green procurement. The framework takes into account the construction, maintenance and end of life phases and focuses on energy and greenhouse gas (GHG) emissions. Threshold values for the production of some additives were also determined to show how LCA tools can help material suppliers to improve the road materials production processes and the road authorities to set limits on the use of different materials based on the environmental criteria. Additive consideration and feedstock energy in road LCAs were also identified as gaps that were looked in detail. The attributes that are important to consider in an asphalt road LCA that seeks to serve as a decision support in a procurement situation are described.A brief literature review was carried out that focused on project LCAs, and specifically those considering pavements, as this level is assumed to be appropriate for questions relevant in a procurement situation. Following the different standards; road LCAs developed all over the world have generated a lot of knowledge and the studies have been different from each other such as in terms of goals and system boundaries. Hence, the patterns observed have been very different from study to study. It was also difficult to assess the decision support level for which the various LCA frameworks or tools were developed. It is important to define system boundaries based on where in the system the decision support is needed. For LCA to be useful for decision support in a procurement situation, it is important to have a clear understanding of the attributes that constitute the life cycle phases and how data of high quality for them are obtained. The level of consistency and transparency of road LCAs becomes increasingly important in pre-procurement and procurement situations. The key attributes used in a road LCA should mirror the material properties used in a pavement design and therefore be closely linked to the performance of the road in its life cycle.From the different case studies, it was found that asphalt production and transportation of materials are usually highest in the energy and GHG emissions chain. It is highly favorable to have the quarry site, the asphalt plant and the construction site not far from each other and to use the electricity that has been produced in an efficient way. Based on the laboratory test results, it is shown that the effects of chemical warm mix asphalt additives (WMAA)s must be evaluated on a case by case basis since WMAA interaction with the aggregate surface mineralogy appears to play a significant role and thus affects its long term structural behavior. Using the material properties obtained from the Superpave indirect tensile test (IDT) results, pavement thickness design was done in which Arlanda aggregate based asphalt mixtures resulted in thinner pavements as compared to Skärlunda aggregate based asphalt mixtures for the same design life period. Energy (feedstock and expended) saving and reduction in GHG emissions were also seen with addition of WMAA, for both aggregate type cases, based on the data used. Importantly, the results presented illustrate the importance of a systems based LCA approach for evaluating the sustainability for different design and construction options. In this context, having actual pavement material properties as the key attributes in the LCA enables a pavement focused assessment of environmental costs associated with different design options.
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| 14. |
- Butt, Ali Azhar, et al.
(author)
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Optimizing the Highway Lifetime by Improving the Self Healing Capacity of Asphalt
- 2012
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In: Transport Research Arena 2012. - : Elsevier BV. ; , s. 2190-2200
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Conference paper (peer-reviewed)abstract
- It is of imminent urgency to optimize the lifetime of asphalt binders from the remaining available crude sources. This paper presents a recently developed model in which the self-healing capacity of bitumen is based on fundamental chemo-mechanical parameters. The implications of the enhanced bitumen healing rates are investigated by utilizing a newly developed Open Life Cycle Assessment framework. From the case study it was concluded that using bitumen with self-healing capacity can lead to a significant reduction in Greenhouse Gas emission and energy usage. Additionally, the importance of knowing the fuels and emission of bitumen modifiers on the highway sustainability was demonstrated.
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| 15. |
- Butt, Ali Azhar, 1984-, et al.
(author)
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The Effect of Wax Modification on the Performance of Mastic Asphalt
- 2010
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In: International Journal of Pavement Research and Technology (IJPRT). - No.300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan : Chinese Society of Pavement Engineering. - 1997-1400. ; 3:2, s. 86-95
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Journal article (peer-reviewed)abstract
- The scope of this study is to evaluate the mechanical performance of the polymer modified mastic asphalt with 4% montan wax (Asphaltan A) additive. The impact of wax modification on binder, binder/filler mixtures and mastic asphalt was investigated in the laboratory. Wax modified binder properties were determined using dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) spectroscopy and conventional tests (softening point, penetration, elastic recovery, breaking point, viscosity and storage stability). The bending beam rheometer (BBR) was used for determining low temperature creep compliance and the tensile stress restrained specimen test (TSRST) for determining low temperature fracture. The fatigue cracking behavior of mastic asphalt was investigated using Superpave Indirect Tensile Test (IDT). Based on HMA Fracture Mechanics the influence of wax on the asphalt mixture resistance to fatigue and brittle cracking has been evaluated. The addition of wax to the polymer modified binder resulted in a viscosity reduction at higher temperatures, indicating a possible lower production and laying temperature as compared to asphalt without wax additive. DMA and BBR results showed some increase in stiffness and a more elastic response of the wax modified binder at medium and low temperatures. The TSRST fracture temperature was higher for the mastic asphalt containing wax, indicating a certain negative impact of wax modification.
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| 16. |
- Butt, Ali Azhar, 1984-, et al.
(author)
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Using Life Cycle Assessment to Optimize Pavement Crack-Mitigation
- 2012
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In: Scarpas et al. (Eds.), 7th RILEM International Conference on Cracking in Pavements<em></em>. - Delft, The Netherlands : Springer Netherlands. ; , s. 299-306
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Conference paper (peer-reviewed)abstract
- Cracking is very common in areas having large variations in the daily temperatures and can cause large discomfort to the users. To improve the binder properties against cracking and rutting, researchers have studied for many years the behaviour of different binder additives such as polymers. It is quite complex, however, to decide on the benefits of a more expensive solution without looking at the long term performance. Life cycle assessment (LCA) studies can help to develop this long term perspective, linking performance to minimizing the overall energy consumption, use of resources and emissions. To demonstrate this, LCA of an unmodified and polymer modified asphalt pavement using a newly developed open LCA framework has been performed. It is shown how polymer modification for improved performance affects the energy consumption and emissions during the life cycle of a road. Furthermore, it is concluded that better understanding of the binder would lead to better optimized pavement design, hence reducing the energy consumption and emissions. A limit in terms of energy and emissions for the production of the polymer was also found which could help the polymer producers to improve their manufacturing processes, making them efficient enough to be beneficial from a pavement life cycle point of view.
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| 17. |
- Edwards, Ylva, et al.
(author)
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Energy saving and environmental friendly wax concept for polymer modified mastic asphalt
- 2010
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In: Materials and Structures. - : Springer Science and Business Media LLC. - 1359-5997 .- 1871-6873. ; 43, s. 123-131
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Journal article (peer-reviewed)abstract
- This paper focuses on the addition of commercial wax as flow improver in polymer modified bitumen intended for use in mastic asphalt pavements under Nordic climatic conditions. Different aspects are dealt with. The aim of the project is to make mastic asphalt used in Sweden today (for bridges, parking decks etc.) more environment friendly and easier to handle. However, wax modification must not have any noticeable negative impact on the performance of mastic asphalt at medium and lower temperatures. The project involves laboratory testing of wax and polymer modified binder mixtures as well as mastic asphalt mixtures. Effects of adding two commercial waxes to one polymer modified bitumen have been studied. The results show that both waxes have a flow improving/viscosity depressant impact on the polymer modified bitumen at higher temperatures, indicating a possible lower laying temperature for the mastic asphalt if modified with such waxes. Moreover, there is a stiffening effect at medium and high temperatures (below placing temperature), indicating a certain positive effect on stability. Concerning low temperature performance, there are results indicating some negative impact on crack susceptibility at low temperatures, more by the addition of one of the waxes than by addition of the other. However, it could be concluded that using up to at least 4% of either wax additive will improve workability for the mastic asphalt product under investigation making it possible to lower working temperatures without seriously affecting its good performance in any negative way.
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| 18. |
- Guarin, Alvaro, et al.
(author)
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An extensive laboratory investigation of the use of bio-oil modified bitumen in road construction
- 2016
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In: Construction and Building Materials. - : Elsevier. - 0950-0618 .- 1879-0526. ; 106, s. 133-139
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Journal article (peer-reviewed)abstract
- Several roads in Iceland with bio-oil modified surface dressings exhibited severe distresses such as bleeding, binder drain down, and eventually as surface dressing sticking to tires. Samples from six road sections were evaluated in the laboratory to determine the causes of the failure. Binders with and without bio-oil, rapeseed oil and fish oil, were evaluated through a comprehensive rheological and chemical characterization. Both oils, exhibited solubility issues with the bitumen; consequently, the oils covered the aggregates, preventing bonding between binder and stones. It appears that fish oil worked a little better than rapeseed oil for binder modification.
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| 19. |
- Mirzadeh, Iman, et al.
(author)
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A Life Cycle Cost Approach based on the Calibrated Mechanistic Asphalt Pavement Design Model
- 2012
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Conference paper (peer-reviewed)abstract
- Life Cycle Cost Analysis (LCCA) provides cost estimation over the life time of a project and thereby helps road administrations, designers, and contractors with choosing an economical design. Calculation of the costs can be based on a pavement design model, such as the Calibrated Mechanistic model (CM), in order to capture the mechanical behaviour of the asphalt pavement. This study aimed to develop an approach for performing comparative LCCA in order to find the most economical design alternative in terms of the total cost for the pavement design life. The integrated LCCA-CM approach was used to evaluate different design alternatives with different rehabilitation intervals for asphalt pavements.
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| 20. |
- Mirzadeh, Iman, et al.
(author)
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Life cycle cost analysis based on the fundamental cost contributors for asphalt pavements
- 2014
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In: Structure and Infrastructure Engineering. - : Informa UK Limited. - 1573-2479 .- 1744-8980. ; 10:12, s. 1638-1647
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Journal article (peer-reviewed)abstract
- A life cycle costing system should include the key variables that drive future costs in order to provide a framework for reducing the risk of under- or overestimating the future costs for maintenance and rehabilitation activities. In Sweden, price of oil products is mostly affected by the global economy rather than by the national economy. Whereas the price index of oil products has had a high fluctuation in different time periods, the cost fluctuation related to labour and equipment has been steady and followed the consumer price index (CPI). Contribution of the oil products was shown to be more than 50% of the total costs regarding construction and rehabilitation of asphalt pavements in Sweden. Consequently, it was observed that neither Swedish road construction price index (Vagindex) nor CPI has properly reflected the price trend regarding the asphalt pavement construction at the project level. Therefore, in this study, a framework is suggested in which energy- and time-related costs are treated with different inflation indices in order to perform a better financial risk assessment regarding future costs.
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