Today, a large quantity of waste is generated from the replacement of residential and commercial roofs. Many of the roofs being upgraded with previously constructed from asphalt shingles. Recycled Asphalt Shingles (RAS) contain nearly 30% of asphalt cement by mass, which can be a useful additive to asphalt pavements. In addition, shingles can offer significant potential savings through recycling and recovery as a construction material in flexible pavement. Currently, one and a half million tons of roofing shingle waste is generated each year in Canada related to the replacement of residential and commercial roofs and 90% of this valuable material is sent to landfills. If engineered properly, the addition of RAS into Hot Mix Asphalt (HMA) can provide significant benefits. The University of Waterloo’s Centre for Pavement and Transportation Technology (CPATT) is committed to working with public and private sector partners to develop sustainable technologies for the pavement industry. Using RAS in HMA can lead to economical, environmental and social benefits. Examples of which are reduced waste going to landfills and a reduction in the quantity of virgin material required. This research has involved the Ontario Centres of Excellence (OCE) and Miller Paving Limited. It was conducted to evaluate the performance of HMA containing RAS in both field and laboratory tests. A varying percentage of RAS was added to six common Ontario surface and binder layer of asphalt mixes. The intent was to determine if RAS could be added to improve performance and provide longer term cost savings. Laboratory testing was performed to evaluate the mix behavior. The elastic properties, fatigue life and resistance to thermal cracking were all evaluated at the CPATT laboratory. The characteristics of the mixes were evaluated by carrying out Dynamic Modulus, Resilient Modulus, Flexural Fatigue and Thermal Stress Restrained Specimen Test (TSRST) tests following American Association of State Highway and Transportation Officials (AASHTO) and American Society for Testing and Materials (ASTM) standards. Field test sections were constructed from HMA containing RAS to monitor the pavement behavior under natural environmental and traffic loading conditions. Evaluation of the field sites was performed using a Portable Falling Weight Deflectometer (PFWD) and carrying out distress surveys following the Ministry of Transportation Ontario (MTO) guidelines. The results to date show the sections performing very well with minimal to no distress developing. The results of the laboratory testing and field performance evaluations have shown encouraging results for the future use of RAS in HMA. If RAS can properly be engineered into HMA it can be a useful additive in both the surface and binder layers of the flexible pavement structure. Ultimately, the use of RAS in HMA can provide both an environmentally friendly and cost effective solution to the Ontario paving industry.

Due to the 15-20 year life span of roofing shingles, 1.5 million tonnes of asphalt roofing shingles are being demolished and replaced annually in Canada from both residential and commercial facilities. These roofing shingles are manufactured from very high quality materials which are considered a valuable by-product. Recycled Asphalt Shingles (RAS), a product containing approximately 30% asphalt cement by mass, is a valuable additive to Hot Mix Asphalt (HMA) pavements and a potential savings for the construction industry. Recycling of demolished asphalt shingles is a significant new step forward in abating the need to put the waste into landfills. This re-use creates a great opportunity in reducing materials being dumped at landfills while providing an additive to HMA mixtures for paving. Therefore, this leads to economic, environmental, and social benefits for all the stakeholders and road users such as reduced need for landfill space, conservation of virgin materials and environment, and financial saving. The research involved evaluating the use of demolished shingles in six typical Ontario Hot Mix Asphalt (HMA) mixtures; HL 3 (1.5% RAS, 13.5% RAP), binder layer mixes SP19 (6% RAS, and 3% RAS, 25% RAP), surface layer mixes SP12.5 FC 1(3% RAS, 17% RAP) and SP12.5 FC2 (6% RAS and 3% RAS, 12% RAP). The six HMA mixes were also designed to contain Recycled Asphalt Pavement (RAP). This further complicated the research as both RAP and RAS were added. All mixes were designed and tested at CPATT laboratory; in addition a test section was paved at the CPATT Test Track. This research involved both laboratory and field evaluations of mixes containing RAS to develop pavement performance modeling for all six mixes using the updated Mechanistic-Empirical Pavement Design Guide (MEPDG). A life-cycle assessment of the six HMA mixes was performed to quantify the environmental impacts using the Pavement Life-Cycle Assessment Tool for Environmental and Economic Effects (PaLATE) and rigorous economic costs/benefits were assessed using Life Cycle Cost Analysis (LCCA). Calibrations of models for Ontario conditions were completed. Test slabs were also constructed to simulate climatic changes by running freeze-thaw cycles based on weather data over the past ten years. Three field test sections located in the Town of Markham and one at the CPATT Test Track were monitored and assessed under as part of the research. Regular pavement condition assessments were carried out on all the test sections by performing non-destructive tests using a Portable Falling Weight Deflectometer (PFWD) and distress survey in accordance with the Ministry of Transportation (MTO) guidelines. The CPATT Test Track was evaluated with both the PFWD and surface distresses, whereas only distress surveys were performed on the three residential streets in the Town of Markham. The evaluations demonstrated that the pavements were in good conditions throughout the monitoring period of the research (four years for the three residential streets in the Town of Markham and two years for the CPATT Test Track). The structural analysis using the MEPDG indicated that Mix 3: SP19 3% RAS and 25% RAP had the best performance followed by Mix 2: SP19 6% RAS when considering all factors in the Life-Cycle Assessment. Mix 3 exhibited maximum savings on environmental emissions, energy and water usage, best adoptability to climatic change and skid resistance properties with minimal life cycle costs. The pavement performance and life-cycle assessment modeling demonstrated encouraging results for the use of RAS in HMA pavements from which guidelines were developed for its use. It is important to note that careful mix design should be carried out when RAS is added to HMA especially when RAP is also used. This includes measuring of all key properties especially at low and high temperatures. In short, RAS can be a valuable additive in both surface and binder layers of HMA pavements. It provides an environmentally friendly and cost-effective innovation for the Ontario paving industry and can be considered for usage elsewhere with appropriate engineering.

Today, a large quantity of waste is generated from the replacement of residential and commercial roofs. Many of the roofs being upgraded with previously constructed from asphalt shingles. Recycled Asphalt Shingles (RAS) contain nearly 30% of asphalt cement by mass, which can be a useful additive to asphalt pavements. In addition, shingles can offer significant potential savings through recycling and recovery as a construction material in flexible pavement. Currently, one and a half million tons of roofing shingle waste is generated each year in Canada related to the replacement of residential and commercial roofs and 90% of this valuable material is sent to landfills. If engineered properly, the addition of RAS into Hot Mix Asphalt (HMA) can provide significant benefits. The University of Waterloo’s Centre for Pavement and Transportation Technology (CPATT) is committed to working with public and private sector partners to develop sustainable technologies for the pavement industry. Using RAS in HMA can lead to economical, environmental and social benefits. Examples of which are reduced waste going to landfills and a reduction in the quantity of virgin material required. This research has involved the Ontario Centres of Excellence (OCE) and Miller Paving Limited. It was conducted to evaluate the performance of HMA containing RAS in both field and laboratory tests. A varying percentage of RAS was added to six common Ontario surface and binder layer of asphalt mixes. The intent was to determine if RAS could be added to improve performance and provide longer term cost savings. Laboratory testing was performed to evaluate the mix behavior. The elastic properties, fatigue life and resistance to thermal cracking were all evaluated at the CPATT laboratory. The characteristics of the mixes were evaluated by carrying out Dynamic Modulus, Resilient Modulus, Flexural Fatigue and Thermal Stress Restrained Specimen Test (TSRST) tests following American Association of State Highway and Transportation Officials (AASHTO) and American Society for Testing and Materials (ASTM) standards. Field test sections were constructed from HMA containing RAS to monitor the pavement behavior under natural environmental and traffic loading conditions. Evaluation of the field sites was performed using a Portable Falling Weight Deflectometer (PFWD) and carrying out distress surveys following the Ministry of Transportation Ontario (MTO) guidelines. The results to date show the sections performing very well with minimal to no distress developing. The results of the laboratory testing and field performance evaluations have shown encouraging results for the future use of RAS in HMA. If RAS can properly be engineered into HMA it can be a useful additive in both the surface and binder layers of the flexible pavement structure. Ultimately, the use of RAS in HMA can provide both an environmentally friendly and cost effective solution to the Ontario paving industry.

Due to the 15-20 year life span of roofing shingles, 1.5 million tonnes of asphalt roofing shingles are being demolished and replaced annually in Canada from both residential and commercial facilities. These roofing shingles are manufactured from very high quality materials which are considered a valuable by-product. Recycled Asphalt Shingles (RAS), a product containing approximately 30% asphalt cement by mass, is a valuable additive to Hot Mix Asphalt (HMA) pavements and a potential savings for the construction industry. Recycling of demolished asphalt shingles is a significant new step forward in abating the need to put the waste into landfills. This re-use creates a great opportunity in reducing materials being dumped at landfills while providing an additive to HMA mixtures for paving. Therefore, this leads to economic, environmental, and social benefits for all the stakeholders and road users such as reduced need for landfill space, conservation of virgin materials and environment, and financial saving. The research involved evaluating the use of demolished shingles in six typical Ontario Hot Mix Asphalt (HMA) mixtures; HL 3 (1.5% RAS, 13.5% RAP), binder layer mixes SP19 (6% RAS, and 3% RAS, 25% RAP), surface layer mixes SP12.5 FC 1(3% RAS, 17% RAP) and SP12.5 FC2 (6% RAS and 3% RAS, 12% RAP). The six HMA mixes were also designed to contain Recycled Asphalt Pavement (RAP). This further complicated the research as both RAP and RAS were added. All mixes were designed and tested at CPATT laboratory; in addition a test section was paved at the CPATT Test Track. This research involved both laboratory and field evaluations of mixes containing RAS to develop pavement performance modeling for all six mixes using the updated Mechanistic-Empirical Pavement Design Guide (MEPDG). A life-cycle assessment of the six HMA mixes was performed to quantify the environmental impacts using the Pavement Life-Cycle Assessment Tool for Environmental and Economic Effects (PaLATE) and rigorous economic costs/benefits were assessed using Life Cycle Cost Analysis (LCCA). Calibrations of models for Ontario conditions were completed. Test slabs were also constructed to simulate climatic changes by running freeze-thaw cycles based on weather data over the past ten years. Three field test sections located in the Town of Markham and one at the CPATT Test Track were monitored and assessed under as part of the research. Regular pavement condition assessments were carried out on all the test sections by performing non-destructive tests using a Portable Falling Weight Deflectometer (PFWD) and distress survey in accordance with the Ministry of Transportation (MTO) guidelines. The CPATT Test Track was evaluated with both the PFWD and surface distresses, whereas only distress surveys were performed on the three residential streets in the Town of Markham. The evaluations demonstrated that the pavements were in good conditions throughout the monitoring period of the research (four years for the three residential streets in the Town of Markham and two years for the CPATT Test Track). The structural analysis using the MEPDG indicated that Mix 3: SP19 3% RAS and 25% RAP had the best performance followed by Mix 2: SP19 6% RAS when considering all factors in the Life-Cycle Assessment. Mix 3 exhibited maximum savings on environmental emissions, energy and water usage, best adoptability to climatic change and skid resistance properties with minimal life cycle costs. The pavement performance and life-cycle assessment modeling demonstrated encouraging results for the use of RAS in HMA pavements from which guidelines were developed for its use. It is important to note that careful mix design should be carried out when RAS is added to HMA especially when RAP is also used. This includes measuring of all key properties especially at low and high temperatures. In short, RAS can be a valuable additive in both surface and binder layers of HMA pavements. It provides an environmentally friendly and cost-effective innovation for the Ontario paving industry and can be considered for usage elsewhere with appropriate engineering.

abstract: This research focused on the structure-property relationships of a rejuvenator to understand the comprehensive rejuvenation mechanism of aged asphalt binder. Aged asphalt such as recycled asphalt shingles (RAS) and reclaimed asphalt pavement (RAP) contain various amounts of asphalt binder. However, the asphalt binder in RAS and RAP is severely aged and inferior in properties compared to a virgin binder. To address this issue, liquid additives have been used under the general title of rejuvenators. That poses an additional challenge associated with the lack of clear metrics to differentiate between softeners and rejuvenators. Therefore, there is a need for a thorough study of rejuvenators. In this study, diverse-sourced rejuvenators have been used in RAS and RAP-modified binders as well as laboratory-prepared aged binders. The properties of the rejuvenated aged binder were characterized at a macro-level and molecular level. The study showed that the performance of the RAS-modified binder was significantly improved after bio-modification by a bio-rejuvenator. This study further evaluated laboratory-prepared aged asphalt rejuvenated with different rejuvenators. The results found that oxidized bitumen became soft after adding rejuvenators, regardless of their source. Molecular dynamics simulation showed that the effective rejuvenator restored the molecular conformation and reduced the size of asphaltene nanoaggregates. The study results showed that due to the specific chemical composition of certain rejuvenators, they may negatively impact the durability of the mixture, especially about its resistance to moisture damage and aging. Computational analysis showed that while the restoration capacity of rejuvenators is related to their penetration into and peptizing of asphaltene nanoaggregates, the durability of the restored aged asphalt is mainly related to the polarizability values of the rejuvenator. Rejuvenators with lower polarizability showed better resistance to aging and moisture damage. In summary, this study develops the rheology-based indicators which relate to the molecular level phenomenon in the rejuvenation mechanism. The rheology-based indicators, for instance, crossover modulus and crossover frequency differentiated the rejuvenators from recycling agents. Moreover, the study found that rejuvenation efficiency and durability are depended on the chemistry of rejuvenators. Finally, based on the learning of chemistry, a chemically balanced rejuvenator is synthesized with superior rejuvenation properties. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2020

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