Residual moisture from incompletely dried aggregates would most likely remain in the Warm Mix Asphalt (WMA) due to its lower production and compaction temperature, resulting in harmful effects on field performance. Dynamic modulus has been recognized as a parameter that reflects the overall behavior of asphalt mixtures and possesses promising correlations with field performance. This study aims to investigate the effects of moisture susceptibility of WMA on dynamic modulus and simulate the field performance with the aid of Mechanistic-Empirical Pavement Design Guide (MEPDG) software. Four distinct sets of WMA specimens were prepared as follows: 1. fully dried aggregates without moisture conditioning; 2. fully dried aggregates with moisture conditioning; 3. incompletely dried aggregates without moisture conditioning; and 4. incompletely dried aggregates with moisture conditioning. Simple Performance Test (SPT) was employed to collect the raw data of dynamic modulus tests and master curves were constructed from the reduced data using Hirsch model. The results show that moisture can negatively influence the dynamic modulus values and moisture conditioning had more effect than residual moisture from incompletely dried aggregates. Two types of distress, fatigue cracking and rutting, were analyzed in the simulation. Moisture can significantly decrease the resistance against rutting and to a lesser extent, the resistance against fatigue cracking.

This thesis investigates the effects of using various percentages of RAP and asphalt binder contents on the dynamic modulus and fatigue resistance of asphalt concrete. Two RAP percentages (20% and 40%) and three binder percentages (plant-mixed, plant-mixed + 0.5%, and plant-mixed + 1.0%) were evaluated. A Superpave gyratory compactor and an asphalt vibratory compactor were used to prepare dynamic modulus samples and fatigue beam samples at 7% air voids. Three replicate samples for each percentage of RAP and asphalt binder content were prepared for testing purposes. An Interlaken Technology Corporation servohydraulic testing machine and a Material Testing System servohydraulic machine were used to determine the dynamic modulus and fatigue resistance of the asphalt samples. Analysis of variance (ANOVA) was used to determine if any of the factors (air voids, percent RAP, and percent asphalt binder) affected the performance criteria (dynamic modulus and fatigue life cycles). Results suggest that as the amount of RAP increases in asphalt concrete, both the dynamic modulus and fatigue life will increase. As per the literature, these results were expected for the dynamic modulus, but not for the fatigue life. It is suspected that the increase in fatigue life for the 40% RAP mixes may be due to the use of a softer binder (PG 64-22 instead of PG 70-22).  It was also found that by increasing the amount of binder in the mixture, the stiffness of asphalt concrete will decrease, but the fatigue life will improve. The fatigue life results showed a strong trend of this improvement for the 20% RAP samples, however, the results for the 40% RAP samples were inconclusive. For dynamic modulus, it was found that the percent RAP, additional binder, frequency, and temperature were all statistically significant with 95% confidence. For the fatigue life, ANOVA showed that the percent RAP and additional binder were statistically significant with 95% confidence. These results suggest that by utilizing a higher percentage of RAP and asphalt binder, it is possible to meet or improve upon the dynamic modulus and fatigue life of the lower percentage of RAP samples. / Master of Science

The purpose of this master thesis is to evaluate the results from the completed SCPT (Seismic Cone Penetration Test) surveys with respect to the methods ability to estimate dynamic young´s modulus. This has been done by comparing the result from SCPT to other seismic methods and dynamic parameters converted from “static” geotechnical surveys. SCPT is a relatively new method which has not been used by Sweco or in Sweden to any greater extent and is therefore of interest to be looked in to. By adding two geophones to an ordinary CPT (Cone Penetration Test) equipment as well as including strike plates, hammer and logger system one can log dynamic parameters in addition to the regular parameters logged by a CPT system. This is done by stopping the otherwise continuous CPT survey every meter and striking the strike plates, which are placed under the tracks of the drilling rig. Seismic waves will then travel through the soil down to the geophones and be used to calculate dynamic parameters. For this master thesis a total of 47 geotechnical and geophysical surveys have been considered. The location of these 47 are approximately 7 km north of Norrköping and have been conducted between the years 2016-2017 for the East Link Project. The geotechnical surveys are composed of weight-sounding, ram-sounding and CPT while the geophysical ones are SCPT, refraction-survey and MASW (Multichannel Analysis of Surface Waves). Static elastic parameters have been calculated using the geotechnical survey results according to the Swedish transportation administrations standardized methods. These have then been converted to dynamic parameters with the help of different relationships. When these have been converted they can be compared to SCPT results and other seismic survey methods which also use wave velocity, Poisson’s ratio and density to calculate dynamic elastic parameters. Based on the results from this thesis it can be concluded that the seismic test add-on to a standard CPTu survey is a good method for accessing dynamic modules and it gives extended information of the soil stratigraphy from one single survey point. After the studies and analyses conducted for this thesis it can be concluded that the proposed conversion between static and dynamic young’s modulus using the Alpan curve gives slightly higher values than the ones derived directly from shear waves using SCPT. The other conversion using cone tip resistance to shear wave velocity gives on the other hand slightly lower values than the ones measured with the SCPT. The analysis also indicate similar trends in results between the different seismic methods. These results does however also shows that the used assumptions are somewhat general for accurate comparisons between the methods.

Hot Mix Asphalt (HMA) has been used over the years for laying roads. It required the aggregate and the binder to be heated to temperatures above 160°C (320°F). Heating the aggregate and binder in large quantities consumed a lot of fuel. This called for alternative solutions in the technology of laying roads. This brought about a new technology called Warm Mix Asphalt (WMA). WMA is an emerging technology that can allow asphalt to be produced and compacted at a significantly lower temperature. In the past, a number of researchers evaluated various WMA mixtures using selected testing procedures in the laboratory. However, none of them evaluated all the major WMA products and compared them with WMA mixtures without an additive using a comprehensive set of testing protocols. This paper presents a comprehensive evaluation result of three major WMA additives (Sasobit®, Evotherm J1 and RedisetTM) regarding their viscosity, tensile strength, moisture sensitivity, dynamic modulus and flow number. These three additives were chosen since all of them are prepared from a base wax product. The asphalt showed a decreasing trend in viscosity with increase in the concentration of the additives. The WMA specimen with additives exhibits similar air voids as control WMA specimens which indicate these WMA additives are effective in compacting asphalt mixtures at low temperatures. The Indirect Tensile Strengths (ITS) and Tensile Strength Ratio (TSR) values of the WMA specimen with admixtures were found to be higher than the control WMA specimens. This result indicates that the admixtures play a significant role in enhancing the properties of WMA. WMA mixtures with additives exhibited higher dynamic modulus than the control WMA at all temperatures. All the specimens passed the requirement of 10,000 cycles of repeated loading. The WMA specimen with Sasobit® additive exhibited the lowest permanent deformation. Based on overall test results it can be concluded that Sasobit®, Evotherm J1 and RedisetTM WMA additives are effective in producing WMA mixtures in the laboratory which have high strengths.

Saskatchewan Highways and Transportation (SDHT) rely on dense-graded hot mix asphalt concrete mixes for construction and rehabilitation of asphalt pavement surfaced highways. As a result of increased commercial truck traffic on the provincial road network, over the last two decades, some of Saskatchewans recently placed dense graded hot mix asphalt concrete (HMAC) pavements have been observed to show a susceptibility to premature permanent deformation in the asphalt mix. One of the aggregate properties thought to have significant influence on mix performance under traffic loading is the shape of the aggregate. Specifically, the physical properties of the fine aggregate (smaller than 5 mm in diameter) are of particular importance in dense graded mixes. Although empirical evidence suggests that there are performance benefits associated with using angular fine aggregate, the relationship of this parameter on mechanistic mix performance and resistance to permanent deformation has not yet been clearly defined.<p>The primary objective of this research was to conduct laboratory analysis to determine the physical, empirical, and mechanistic behaviour sensitivity to the proportion of manufactured and natural fine aggregate in SDHT Type 72 hot mix asphalt concrete. The second objective of this research was to compare the mechanistic behaviour of the Type 72 mixes considered in this research to conventional SDHT Type 70 structural hot mix asphalt concrete.<p>Physical and mechanistic properties of a SDHT Type 72 mix at levels of 20, 40, and 60 percent manufactured fines as a portion of total fines (smaller than 5 mm), and for a SDHT Type 70 mix (which contained 38 percent manufactured fines) were evaluated. Ten repeat samples were compacted for each mix using 75-blow Marshall compaction, and ten samples for each mix were compacted using the Superpave gyratory compaction protocols. Marshall stability and flow testing was conducted on the Marshall-compacted samples. Triaxial frequency sweep testing was conducted on the gyratory-compacted samples using the Rapid Triaxial Tester (RaTT) at 20°C. The testing was conducted at axial loading frequencies of 10 and 0.5 Hz, and at deviatoric stress states of 370, 425, and 500 kPa, respectively. The resulting dynamic modulus, axial and radial microstrains, Poissons ratio, and phase angle were evaluated.<p>The research hypothesis stated that the increased amount of manufactured fines improves mechanistic properties of the Type 72 mix under typical field state conditions, and Type 72 mix with increased manufactured fines can exhibit mechanistic properties equivalent to or exceeding those of a typical type 70 mix. <p>Based on the improved densification properties, increased Marshall stability, increased dynamic modulus, and reduced radial and axial strains, it was demonstrated that increasing manufactured fines content in the SDHT Type 72 mix does improve the mechanistic properties of this dense-graded asphalt mix. It should be noted that there appears to be a minimum level of manufactured fines content that is required to affect mix response to loading, and that this threshold lies somewhere between 40 and 60 percent manufactured fines content for the Type 72 mix tested as part of this research.<p>Further, the Type 72 mix exhibited comparable or improved mechanistic properties relative to the Type 70 mix, which SDHT consider a structural mix. This is illustrated by the Type 72 mix with 60 percent manufactured fines resulting in higher Marshall stability and dynamic modulus, and lower axial microstrains than the Type 70 mix evaluated in this study.<p>It is recommended that other Type 72 and Type 70 mixes are evaluated using similar testing protocols. In addition, field test sections should be used to further verify the research hypothesis investigated here. <p>Economic analysis indicates that substantial savings in life cycle costs of SHDT asphalt concrete surfaced roadways can be realized by engineering well-performing, rut-resistant mixes. The life cycle costs can be reduced annually by approximately $7.4 million, which translates into $102.5 million savings over 18 years, during which the entire pavement network would be resurfaced with well-performing asphalt concrete mixes.<p>Further, enhanced crushing of smaller aggregate top size decreases the amount of rejected material, and increases manufactured fines to coarse aggregate ratio, resulting not only in better engineering properties, but also in the optimized use of the provinces diminishing gravel resources. Pressures on aggregate sources are also reduced by improving life cycle performance of Saskatchewan asphalt concrete pavements. The total potential aggregate savings that can be realized by implementing well-performing Type 72 HMAC mixes amount to 4.3 million metric tonnes of aggregate in the next 42 years. These aggregate savings can help decrease the predicted shortage of aggregate between 2007 and 2049 by approximately 6 percent. The total potential cost savings after 18 years of paving 500 km per year with rut-resistant, well-performing HMAC mixes amount to $112.4 million in present value dollars. The 42 year savings amount to $193.7 million in present day dollars. It is recommended that a more detailed economic analysis be carried out.

In 2007, the Mechanistic-Empirical Pavement Design Guide (MEPDG) was successfully approved as the new American Association of State Highway and Transportation Officials (AASHTO) pavement design standard (Von Quintus et al., 2007). Calibration and validation of the MEPDG is currently in progress in several provinces across Canada. The MEPDG will be used as the standard pavement design methodology for the foreseeable future (Tighe, 2013). This new pavement design process requires several parameters specific to local conditions of the design location. In order to perform an accurate analysis, a database of parameters including those specific to local materials, climate and traffic are required to calibrate the models in the MEPDG. In 1989, the Canadian Strategic Highway Research Program (C-SHRP) launched a national full scale field experiment known as the Canadian Long-Term Pavement Performance (C-LTPP) program. Between the years, 1989 and 1992, a total of 24 test sites were constructed within all ten provinces. Each test site contained multiple monitored sections for a total of 65 sections. Each of these sites received rehabilitation treatments of various thicknesses of asphalt overlays. The C-LTPP program attempted to design and build the test sections across Canada so as to cover the widest range of experimental factors such as traffic loading, environmental region, and subgrade type. With planned strategic pavement data collection cycles, it would then be possible to compare results obtained at different test sites (i.e. across traffic levels, environmental zones, soil types) across the country. The United States Long-Term Pavement Performance (US-LTPP) database is serving as a critical tool in implementing the new design guide. The MEPDG was delivered with the prediction models calibrated to average national conditions. For the guide to be an effective resource for individual agencies, the national models need to be evaluated against local and regional performance. The results of these evaluations are being used to determine if local calibration is required. It is expected that provincial agencies across Canada will use both C-LTPP and US-LTPP test sites for these evaluations. In addition, C-LTPP and US-LTPP sites provide typical values for many of the MEPDG inputs (C-SHRP, 2000). The scope of this thesis is to examine the existing data in the C-LTPP database and assess its relevance to Canadian MEPDG calibration. Specifically, the thesis examines the dynamic modulus parameter (|E*|) and how it can be computed using existing C-LTPP data and an Artificial Neural Network (ANN) model developed under a Federal Highway Administration (FHWA) study (FHWA, 2011). The dynamic modulus is an essential property that defines the stiffness characteristics of a Hot Mix Asphalt (HMA) mixture as a function of both its temperature and rate of loading. |E*| is also a primary material property input required for a Level 1 analysis in the MEPDG. In order to perform a Level 1 MEPDG analysis, detailed local material, environmental and traffic parameters are required for the pavement section being analyzed. Additionally, it can be used in various pavement response models based on visco-elasticity. The dynamic modulus values predicted using both Level 2 and Level 3 viscosity-based ANN models in the ANNACAP software showed a good correlation to the measured dynamic modulus values for two C-LTPP test sections and supplementary Ontario mixes. These findings support previous research findings done during the development of the ANN models. The viscosity-based prediction model requires the least amount data in order to run a prediction. A Level 2 analysis requires mix volumetric data as well as viscosity testing and a Level 3 analysis only requires the PG grade of the binder used in the HMA. The ANN models can be used as an alternative to the MEPDG default predictions (Level 3 analysis) and to develop the master curves and determine the parameters needed for a Level 1 MEPDG analysis. In summary, Both the Level 2 and Level 3 viscosity-based model results demonstrated strong correlations to measured values indicating that either would be a suitable alternative to dynamic modulus laboratory testing. The new MEPDG design methodology is the future of pavement design and research in North America. Current MEPDG analysis practices across the country use default inputs for the dynamic modulus. However, dynamic modulus laboratory characterization of asphalt mixes across Canada is time consuming and not very cost-effective. This thesis has shown that Level 2 and Level 3 viscosity-based ANN predictions can be used in order to perform a Level 1 MEPDG analysis. Further development and use of ANN models in dynamic modulus prediction has the potential to provide many benefits.

Saskatchewan Highways and Transportation (SDHT) rely on dense-graded hot mix asphalt concrete mixes for construction and rehabilitation of asphalt pavement surfaced highways. As a result of increased commercial truck traffic on the provincial road network, over the last two decades, some of Saskatchewans recently placed dense graded hot mix asphalt concrete (HMAC) pavements have been observed to show a susceptibility to premature permanent deformation in the asphalt mix. One of the aggregate properties thought to have significant influence on mix performance under traffic loading is the shape of the aggregate. Specifically, the physical properties of the fine aggregate (smaller than 5 mm in diameter) are of particular importance in dense graded mixes. Although empirical evidence suggests that there are performance benefits associated with using angular fine aggregate, the relationship of this parameter on mechanistic mix performance and resistance to permanent deformation has not yet been clearly defined.<p>The primary objective of this research was to conduct laboratory analysis to determine the physical, empirical, and mechanistic behaviour sensitivity to the proportion of manufactured and natural fine aggregate in SDHT Type 72 hot mix asphalt concrete. The second objective of this research was to compare the mechanistic behaviour of the Type 72 mixes considered in this research to conventional SDHT Type 70 structural hot mix asphalt concrete.<p>Physical and mechanistic properties of a SDHT Type 72 mix at levels of 20, 40, and 60 percent manufactured fines as a portion of total fines (smaller than 5 mm), and for a SDHT Type 70 mix (which contained 38 percent manufactured fines) were evaluated. Ten repeat samples were compacted for each mix using 75-blow Marshall compaction, and ten samples for each mix were compacted using the Superpave gyratory compaction protocols. Marshall stability and flow testing was conducted on the Marshall-compacted samples. Triaxial frequency sweep testing was conducted on the gyratory-compacted samples using the Rapid Triaxial Tester (RaTT) at 20°C. The testing was conducted at axial loading frequencies of 10 and 0.5 Hz, and at deviatoric stress states of 370, 425, and 500 kPa, respectively. The resulting dynamic modulus, axial and radial microstrains, Poissons ratio, and phase angle were evaluated.<p>The research hypothesis stated that the increased amount of manufactured fines improves mechanistic properties of the Type 72 mix under typical field state conditions, and Type 72 mix with increased manufactured fines can exhibit mechanistic properties equivalent to or exceeding those of a typical type 70 mix. <p>Based on the improved densification properties, increased Marshall stability, increased dynamic modulus, and reduced radial and axial strains, it was demonstrated that increasing manufactured fines content in the SDHT Type 72 mix does improve the mechanistic properties of this dense-graded asphalt mix. It should be noted that there appears to be a minimum level of manufactured fines content that is required to affect mix response to loading, and that this threshold lies somewhere between 40 and 60 percent manufactured fines content for the Type 72 mix tested as part of this research.<p>Further, the Type 72 mix exhibited comparable or improved mechanistic properties relative to the Type 70 mix, which SDHT consider a structural mix. This is illustrated by the Type 72 mix with 60 percent manufactured fines resulting in higher Marshall stability and dynamic modulus, and lower axial microstrains than the Type 70 mix evaluated in this study.<p>It is recommended that other Type 72 and Type 70 mixes are evaluated using similar testing protocols. In addition, field test sections should be used to further verify the research hypothesis investigated here. <p>Economic analysis indicates that substantial savings in life cycle costs of SHDT asphalt concrete surfaced roadways can be realized by engineering well-performing, rut-resistant mixes. The life cycle costs can be reduced annually by approximately $7.4 million, which translates into $102.5 million savings over 18 years, during which the entire pavement network would be resurfaced with well-performing asphalt concrete mixes.<p>Further, enhanced crushing of smaller aggregate top size decreases the amount of rejected material, and increases manufactured fines to coarse aggregate ratio, resulting not only in better engineering properties, but also in the optimized use of the provinces diminishing gravel resources. Pressures on aggregate sources are also reduced by improving life cycle performance of Saskatchewan asphalt concrete pavements. The total potential aggregate savings that can be realized by implementing well-performing Type 72 HMAC mixes amount to 4.3 million metric tonnes of aggregate in the next 42 years. These aggregate savings can help decrease the predicted shortage of aggregate between 2007 and 2049 by approximately 6 percent. The total potential cost savings after 18 years of paving 500 km per year with rut-resistant, well-performing HMAC mixes amount to $112.4 million in present value dollars. The 42 year savings amount to $193.7 million in present day dollars. It is recommended that a more detailed economic analysis be carried out.

In 2007, the Mechanistic-Empirical Pavement Design Guide (MEPDG) was successfully approved as the new American Association of State Highway and Transportation Officials (AASHTO) pavement design standard (Von Quintus et al., 2007). Calibration and validation of the MEPDG is currently in progress in several provinces across Canada. The MEPDG will be used as the standard pavement design methodology for the foreseeable future (Tighe, 2013). This new pavement design process requires several parameters specific to local conditions of the design location. In order to perform an accurate analysis, a database of parameters including those specific to local materials, climate and traffic are required to calibrate the models in the MEPDG. In 1989, the Canadian Strategic Highway Research Program (C-SHRP) launched a national full scale field experiment known as the Canadian Long-Term Pavement Performance (C-LTPP) program. Between the years, 1989 and 1992, a total of 24 test sites were constructed within all ten provinces. Each test site contained multiple monitored sections for a total of 65 sections. Each of these sites received rehabilitation treatments of various thicknesses of asphalt overlays. The C-LTPP program attempted to design and build the test sections across Canada so as to cover the widest range of experimental factors such as traffic loading, environmental region, and subgrade type. With planned strategic pavement data collection cycles, it would then be possible to compare results obtained at different test sites (i.e. across traffic levels, environmental zones, soil types) across the country. The United States Long-Term Pavement Performance (US-LTPP) database is serving as a critical tool in implementing the new design guide. The MEPDG was delivered with the prediction models calibrated to average national conditions. For the guide to be an effective resource for individual agencies, the national models need to be evaluated against local and regional performance. The results of these evaluations are being used to determine if local calibration is required. It is expected that provincial agencies across Canada will use both C-LTPP and US-LTPP test sites for these evaluations. In addition, C-LTPP and US-LTPP sites provide typical values for many of the MEPDG inputs (C-SHRP, 2000). The scope of this thesis is to examine the existing data in the C-LTPP database and assess its relevance to Canadian MEPDG calibration. Specifically, the thesis examines the dynamic modulus parameter (|E*|) and how it can be computed using existing C-LTPP data and an Artificial Neural Network (ANN) model developed under a Federal Highway Administration (FHWA) study (FHWA, 2011). The dynamic modulus is an essential property that defines the stiffness characteristics of a Hot Mix Asphalt (HMA) mixture as a function of both its temperature and rate of loading. |E*| is also a primary material property input required for a Level 1 analysis in the MEPDG. In order to perform a Level 1 MEPDG analysis, detailed local material, environmental and traffic parameters are required for the pavement section being analyzed. Additionally, it can be used in various pavement response models based on visco-elasticity. The dynamic modulus values predicted using both Level 2 and Level 3 viscosity-based ANN models in the ANNACAP software showed a good correlation to the measured dynamic modulus values for two C-LTPP test sections and supplementary Ontario mixes. These findings support previous research findings done during the development of the ANN models. The viscosity-based prediction model requires the least amount data in order to run a prediction. A Level 2 analysis requires mix volumetric data as well as viscosity testing and a Level 3 analysis only requires the PG grade of the binder used in the HMA. The ANN models can be used as an alternative to the MEPDG default predictions (Level 3 analysis) and to develop the master curves and determine the parameters needed for a Level 1 MEPDG analysis. In summary, Both the Level 2 and Level 3 viscosity-based model results demonstrated strong correlations to measured values indicating that either would be a suitable alternative to dynamic modulus laboratory testing. The new MEPDG design methodology is the future of pavement design and research in North America. Current MEPDG analysis practices across the country use default inputs for the dynamic modulus. However, dynamic modulus laboratory characterization of asphalt mixes across Canada is time consuming and not very cost-effective. This thesis has shown that Level 2 and Level 3 viscosity-based ANN predictions can be used in order to perform a Level 1 MEPDG analysis. Further development and use of ANN models in dynamic modulus prediction has the potential to provide many benefits.

abstract: Oxidative aging is an important factor in the long term performance of asphalt pavements. Oxidation and the associated stiffening can lead to cracking, which in turn can lead to the functional and structural failure of the pavement system. Therefore, a greater understanding of the nature of oxidative aging in asphalt pavements can potentially be of great importance in estimating the performance of a pavement before it is constructed. Of particular interest are the effects of aging on asphalt rubber pavements, due to the fact that, as a newer technology, few asphalt rubber pavement sections have been evaluated for their full service life. This study endeavors to shed some light on this topic. This study includes three experimental programs on the aging of asphalt rubber binders and mixtures. The first phase addresses aging in asphalt rubber binders and their virgin bases. The binders were subjected to various aging conditions and then tested for viscosity. The change in viscosity was analyzed and it was found that asphalt rubber binders exhibited less long term aging. The second phase looks at aging in a laboratory environment, including both a comparison of accelerated oxidative aging techniques and aging effects that occur during long term storage. Dynamic modulus was used as a tool to assess the aging of the tested materials. It was found that aging materials in a compacted state is ideal, while aging in a loose state is unrealistic. Results not only showed a clear distinction in aged versus unaged material but also showed that the effects of aging on AR mixes is highly dependant on temperature; lower temperatures induce relatively minor stiffening while higher temperatures promote much more significant aging effects. The third experimental program is a field study that builds upon a previous study of pavement test sections. Field pavement samples were taken and tested after being in service for 7 years and tested for dynamic modulus and beam fatigue. As with the laboratory aging, the dynamic modulus samples show less stiffening at low temperatures and more at higher temperatures. Beam fatigue testing showed not only stiffening but also a brittle behavior. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2010

No description available.