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Thermal cracking significantly impacts the structural integrity of flexible pavements, particularly in colder regions like Canada. Limited studies investigated the impact of plastic modification of asphalt binders and mixtures using the wet method on the low-temperature performance of asphalt materials. The plastic material utilized in this project is multilayer plastic packaging (MPP). This study aims to determine whether MPP can be integrated to enhance the performance of the MPP-modified binder and MPP-modified mixtures, especially considering that MPP accounts for just over 40% of total plastic usage, making it the largest end-use market segment. This research evaluates the impact on rheological and mechanical behaviour when introducing MPP additives to conventional hot mix asphalt. This study used the wet method to test MPP-modified asphalt materials at 2%, 4%, and 8% (by weight of the asphalt binder). Test results demonstrate that the MPP modification percentage should ideally not exceed 2% as blends with 4% MPP or higher exhibited lower performance at low temperatures. The use of a softer binder as a base binder would help increase the MPP modification rates, but this hypothesis needs to be validated experimentally. [ABSTRACT FROM AUTHOR]

Using geopolymer as a modifier for asphalt binders and mixtures gained momentum for investigation in recent decades. Limited research investigations attempted to link the effect of temperature and traffic loading on the rheological properties and performance of geopolymer-modified asphalt binders. The primary objective of this study is to evaluate the effect of fly ash-based geopolymer (GF), styrene-butadiene-styrene (SBS), and the combination of GF with SBS on the rheological properties and performance of asphalt binders at low and intermediate temperatures. The rheological properties and performance of neat and modified asphalt binders (4%GF, 8%GF,12%GF, 2%SBS, and hybrid (2%SBS+8%GF)) were evaluated utilizing dynamic shear rheometer (DSR) and bending beam rheometer (BBR) devices. To evaluate the fatigue resistance of asphalt binders, the linear amplitude sweep (LAS) and viscoelastic continuum damage (VECD) models were applied. The dynamic or complex modulus and moisture damage resistance were measured to investigate the influence of modifiers on the performance of asphalt mixtures. The findings demonstrated that for both unaged and RTFO-aged asphalt binders, additives reduced the temperature sensitivity of both G′ and G″. When the binders were exposed to long-term aging using a pressure aging vessel (PAV), it was noticed that the 8%GF binder became more susceptible to temperature changes. The 2%SBS binder had the lowest creep stiffness compared with the neat and other modifiers, while the hybrid binder exhibited the highest resistance to fatigue distress at different temperatures compared with the other binders. The modified asphalt mixes (8%GF, 2%SBS, and hybrid) achieved the maximum tensile strength ( S t ) compared with the neat asphalt binder, with an increase of more than 80%. The S t increased from 580.4 kPa to 740.4 kPa, 884.8 kPa, and 917.4 kPa by utilising the 8%GF, 2%SBS, and hybrid binders, respectively. Furthermore, the modified asphalt mixture exhibited more ability to resist cracking, attaining the highest fracture energy in dry and freeze-thaw conditions. [ABSTRACT FROM AUTHOR]

The amount of residual Multi-layer Plastic Packaging (MPP) in Canada has greatly increased in the last two decades, which has economic and environmental consequences. MPP is primarily made up of two or more layers of Polyethylene (PE), Polyester (PET), Nylon (NY), and Metalized Polyester (METPET). While MPP has not been used as an asphalt modifier, some of the materials commonly found in MPP, such as PE and PET, have also been successfully used as asphalt modifiers. Nevertheless, a few recent studies have demonstrated the potential for reusing MPP as an asphalt modifier to improve asphalt pavement performance. Recycling post-industrial MPP instead of using raw polymers could lead to economic and environmental benefits. However, a comprehensive study to evaluate MPP as a viable asphalt additive is lacking. The main objective of this study is to evaluate the feasibility of using MPP as an asphalt modifier via the wet method, considering the physical, thermal, rheological, and storage properties of the MPP-modified binder at different MPP concentrations (2%, 4%, and 8%) in asphalt cement (PG 58–28). MPP-modified binders were evaluated using the following instruments: Differential Scanning Calorimeter (DSC), Thermogravimetric Analysis (TGA), Superpave Dynamic Shear Rheometer (DSR), Rotational Viscosity (RV), and Environmental Scanning Electron Microscopy (ESEM). Test results indicated that the incorporation of MPP has a strong potential to improve permanent deformation resistance at high temperatures. In addition, MPP shows a moderate impact on fatigue cracking performance at intermediate temperatures. Overall, in low-temperature climates, using less than 4% of MPP additives would offer higher fatigue damage resistance along with adequate permanent deformation. In high-temperature climates, higher concentrations of additives may be preferable to resist permanent deformation. Finally, MPP is a challenge for existing recycling systems, and its incorporation into asphalt applications may develop more sustainable materials that would contribute to circular economy principles. [ABSTRACT FROM AUTHOR]

Additives are widely used to enhance the rheological and performance properties of asphalt binder to satisfy the demands of extreme loading and climatic conditions. Meanwhile, adding to the complexity of asphalt binder behaviour that requires more time, effort, and material resources during laboratory work. The purpose of this research was to use Artificial Neural Networks (ANNs) to predict the recovery (R) and nonrecoverable compliance (J n r ) behaviour of asphalt binder based on mechanical test parameters and rheological properties of asphalt binder. A comprehensive experimental database consisting of the results of the frequency sweep and Multiple Stress Creep Recovery (MSCR) test using a dynamic shear rheometer (DSR) at five test temperatures (46 ∘ C, 52 ∘ C, 58 ∘ C, 64 ∘ C, and 70 ∘ C). Prediction models for R and J n r of asphalt binder modified with different contents of fly ash, fly ash-based geopolymer, glass powder/fly ash-based geopolymer, and styrene–butadiene styrene (SBS) were developed. The ANNs model was developed using five input parameters (temperature, frequency, storage modulus, loss modulus, and viscosity) and one hidden layer with five neurons. The results pointed out that the hybrid and 4%SBS binders achieved the highest ability to resist extremely heavy traffic and to recover the deformation with 60.1% and 85.5% at 46 ∘ C, respectively, compared with the other modified asphalt binders. Excellent R-values for the total data set of 0.937, 0.997, 0.985, and 0.987 for J n r 3.2 of unaged binder, J n r 3.2 of aged binder, R 3.2 of unaged binder, and R 3.2 of aged binder, respectively. Therefore, the ANNs model is appropriate tool to predict the R 3.2 and J n r 3.2 using unaged or aged binders at different temperatures. [ABSTRACT FROM AUTHOR]

Limited field investigations have evaluated the impact of traffic on the snow melting capacity of salts. This paper will describe an extensive field study that includes 1,200 tests that are conducted during 100 snow events over three winter seasons (2012, 2013, and 2014) to quantify the traffic impact on snow melting capacity. The tests will be conducted in an active parking lot, and on parking stalls and driveways, which could increase the applicability of the results to real-world scenarios. The deicing performance of salt will be compared between both areas with different traffic patterns for bare pavement regain time (BPRT). The developed model quantified the reduction in BPRT from 21% for a low traffic volume of 5 vehicles/h to an 86% reduction for a high traffic volume of 50 vehicles/h. The deicing performance models that were calibrated for parking stalls and driveways could be directly used to determine the most cost-effective application rates to treat parking lots and sidewalks based on specific weather, facilities, and traffic conditions. [ABSTRACT FROM AUTHOR]

The study presented in this paper analyzed four long-term pavement performance (LTPP) test sections located in the states of New York (NY) and California (CA). Two of them are flexible pavement sections, whereas the other two are composite pavement sections. Two levels of analysis—in-state analysis and cross-state analysis—were performed for these pavement sections to determine the impacts of traffic and climate conditions. The performance of the pavement sections was evaluated in respect of thermal cracking and rutting resistance. The in-state analysis focused on comparing the pavement sections located in the same state. The two pavement sections located in CA exhibited insignificant variation in thermal cracking, although one of them had an additional 1.5" (38 mm) dense-graded asphaltic concrete (AC) layer. On the other hand, the additional 1.5" (38 mm) AC layer resulted in a significant reduction in the rutting depth in one pavement section. The in-state analysis of the two pavement sections located in NY revealed that the 0.8" (20.4 mm) chip seal layer had significantly low resistance to thermal cracking and rutting. The cross-state analysis examined pavement sections of comparable structural capacities—two with low structural capacity, and two with high structural capacity. The performance comparison of the two pavement sections with low structural capacity revealed that the chip seal layer exhibited a significantly high rutting depth, i.e., low rutting resistance under high traffic loads in a freezing climate. On the contrary, the two pavement sections with high structural capacity showed relatively high rutting resistance in both warmer and freezing climates. Furthermore, this paper presents the pavement deterioration models for rutting and thermal cracking in the LTPP test sections. These models were developed using multiple linear regression considering the pavement service life (age), traffic load (average annual daily truck traffic, AADTT), and climate impact (freezing index, FI). The deterioration models had coefficients of determination (r2) in the range of 0.82–0.99 and standard errors varying from 0.01 to 9.92, which indicate that the models are reliable. [ABSTRACT FROM AUTHOR]

Modifying asphalt binders is an effective method of improving the performance of asphalt pavement, such as its resistance to rutting. However, because modification changes the behaviour of binders, substantial laboratory testing is required before field application to determine the best mixtures. This research aimed to evaluate the impacts of temperature, stresses, polymer type, and modification rate on the rutting behaviour of the asphalt binder modified with fly-ash-based geopolymer (GF), styrene butadiene styrene (SBS), and a combination of SBS and GF. The rheological properties of asphalt binders were investigated using the frequency sweep test at various temperatures. Additionally, the multiple stress creep recovery test was conducted at various temperatures and stresses to calculate the non-recoverable creep compliance (J n r ) and the percent strain recovery (R). The rutting resistance of asphalt mixture was assessed using the Hamburg wheel rut test. The results revealed that the asphalt binder with 8% geopolymer (8%GF) exhibited the best response in terms of complex shear modulus (G * ), rutting factor (G * /sin δ), R, and J n r compared to the 4%GF and 12%GF at different temperatures. Another interesting finding is that GF's use in the hybrid binder (2%SBS + 8%GF) led to a significant increase in the shear complex modulus and a decrease in the phase angle compared to the binder modified with 2%SBS. The geopolymer decreased the binder's sensitivity to temperature for both unaged and RTFO asphalt binders. The hybrid binder would also improve strain recovery under high stress and temperatures and the ability to withstand severe traffic loads. Furthermore, there is a crucial relationship between temperature and J n r , which could help asphalt pavement designers select suitable modifiers considering the local climate and traffic volume. [ABSTRACT FROM AUTHOR]

Accurate forecasts of public transportation ridership are key components to a transit agency's management program. These forecasts are used to develop revenue projections that are then imputed into short-term and long-term maintenance, rehabilitation, and capital investment programming. The forecasts are complicated by the fact that many of the causes of the underlying variability, such as socioeconomic and land-use factors, are not constant over the network. Failure to account for these spatial processes will yield biased, inefficient, and inconsistent demand estimates. To overcome these challenges, the current paper presents a spatial Durbin model for analyzing the change in the New York City subway ridership between 2011 and 2016. The results indicate that subway stations experienced a greater increase in ridership over the study period when the stations served more train lines, were located in areas comprised of census tracts with a greater number of tax units (residential, commercial, etc.), or served lower mean household incomes. Furthermore, the subway stations located in areas surrounded by census tracts with more commercial property or higher median family income are also expected to have a greater increase in ridership. Lastly, ridership at a given station decreases due to an increase in ridership at neighboring stations. This may indicate that a change in ridership at a station is due, in part, to riders in a region changing which station they use instead of riders shifting from alternative modes of transportation. [ABSTRACT FROM AUTHOR]

Severe Canadian winter conditions and growing traffic volumes are vital factors resulting in a reduction of the service life of flexible pavements. Researchers and engineers strived to develop several additives to develop balanced asphalt mixers capable of resisting distresses that caused deterioration of flexible pavements in Canada. In this study, a critical literature review regarding the use of geopolymers and their application in construction materials is provided. Moreover, an experimental matrix of laboratory testing was conducted to study the rheological and microstructural properties of the PG 58-28 asphalt binder, with different percentages (0%, 3%, 6%, and 9%) of geopolymer. The effect of geopolymer-curing time on rheological properties was investigated. Rotational viscometer, dynamic shear rheometer (DSR), and environmental scanning electron microscopy (ESEM) imaging devices were used to compare the performance of control binder with a binder with different percentages of geopolymers. Results indicated that the increase in the geopolymer content and the curing time affect the rheological behavior of the asphalt binder by increasing its viscosity, complex shear modulus, and failure temperature. Samples with higher geopolymer percentage exhibited better performance in terms of rutting resistance. Moreover, an increase in the failure temperature of modified asphalt binder with 9% geopolymer is recorded as 8.58%, 14.2%, and 15.2% for curing times of 2, 7, and 14 days, respectively, compared with virgin asphalt. Furthermore, the nanoparticles appear to be well dispersed in the binder, and increasing the percentage of the geopolymer does not seem to affect the microstructure of the binder. Overall research conclusion is that geopolymer application resulted in a potential enhancement of some of the properties of the asphalt binder. [ABSTRACT FROM AUTHOR]