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The availability of high-quality aggregate for infrastructure development in Canada has significantly decreased. This reduction has posed significant challenges, particularly in large urban areas across Canada. Moreover, exploring the potential of incorporating innovative by-products into pavement structures has displayed potential advantages in technical, economic, and environmental aspects. The methodology presented in this paper is based on several research projects from over the past twenty years. This case study is based on the several research projects that have been conducted at the Centre for Pavement and Transportation Technology (CPATT) in Canada. The focus of this paper is developing a framework that can be used to evaluate the use of recycled materials in asphalt pavement. These include recycled concrete aggregate (RCA); recycled asphalt roof shingles (RAS); recycled crumb rubber (RCR); and recycled asphalt roof shingles (RAS) in asphalt pavement. In addition, the use of RCA in concrete pavement will also be evaluated. In addition, the use of RCA in concrete pavement will also be evaluated. A methodology and strategy for implementing these materials and designs into specifications, while also managing risk, are outlined. Finally, the work presents a life cycle assessment analysis, including the analysis of cost and sustainability. Overall, the paper illustrates the process of evaluating products, technologies, and designs from technical, economic, and environmental viewpoints, and then implementing them in a robustly engineered way. Generally, the collected data results from the lab, field performance of the test sites, and sustainability and Life Cycle Cost Assessment (LCCA) analyses are very promising. For example, the Hot Mix Asphalt (HMA) pavement design with a 40% RAP was the most environmentally friendly. Meanwhile, it was determined that the HMA mix comprising 20% RAP and 20% Crumb Rubber Modifier (CRM) was found to be the most creative and environmentally friendly option. According to another study, higher storage durations were shown to improve RAP and virgin binders' blending, thereby raising the general quality of HMA and RAP mixtures. Furthermore, the study discovered that mixtures containing various types of untreated CRCA in different amounts had higher Indirect Tensile Strength (ITS), rutting resistance, and stiffness modulus than the control mix, which contained 0% coarse recycled concrete aggregate (CRCA). This suggests that the effective utilization of recycled materials is a viable approach with the capacity to significantly enhance the adoption of recycled components in asphalt pavements. [ABSTRACT FROM AUTHOR]

The use of Lightweight Cellular Concrete (LCC) as a subbase alternative to typical flexible pavement subbase material in cold regions is gaining attention. Since a setback of using LCC is its high cement content, which is a significant source of carbon dioxide (CO2) emissions, it becomes imperative to consider this aspect when proposing LCC for pavement applications. This study evaluated the environmental impact of three densities (400, 475, and 600 kg/m³) of LCC produced with two methods (wet and dry mix) and compared to two types of unbound granular material (granular A and B) as flexible pavement subbase. The pavement performance was predicted using MEPDG and WESLEA software and compared with measured field responses as a basis for maintenance strategy. The Life Cycle Assessment (LCA) results showed that lower-density LCC pavements decreased environmental costs by reducing total life CO2 emissions by up to 16% and reducing environmental impact for Carbon monoxide, Sulphur dioxide, Nitrogen oxide, Particulate Matter (PM)2.5, PM10 and total PM compared to granular A and B pavements. As LCC density increased, more emissions occurred, showing the importance of density to emissions output. This research demonstrates the potential benefits of using LCC as an alternative subbase pavement material. [ABSTRACT FROM AUTHOR]

The objective of engineers to improve the long-term performance of road infrastructure in changing global climate has led to the development of alternate materials for pavement construction. Lightweight cellular concrete (LCC) is a viable option for colder climates where pavements undergo several freeze-thaw cycles each year, resulting in faster deterioration of pavements. This is due to LCCs' excellent freeze-thaw resistance, ease of placement, and potential sustainability benefits such as reduced use of virgin material and industrial by-products. However, there is a need to quantify these benefits and develop unified specifications for using LCC in the pavement structure. Therefore, this study examined the performance of flexible pavement sections that included a subbase layer, unbound granular materials for the control section, and three LCC densities (400, 475, and 600 kg/m3) for the LCC sections. Post-construction evaluation of pavement stiffness and roughness were evaluated using a Lightweight deflectometer and SurPro equipment. The results showed that LCC subbase thickness ≥ 250 mm produced over 22% smoother riding surfaces than unbound granular pavements while increasing pavement stiffness by up to 21%. Finally, this study recommends that LCC subbase thickness should not be thinner than 250 mm when using densities below 475 kg/m3 over weak subgrades. [ABSTRACT FROM AUTHOR]

Pavement infrastructures have become vulnerable to damage as they were not designed to withstand the aggressions of extreme weather events such as flooding, induced by climate change. In Ontario, flooding tops the list of climate change hazards having a consequential impact on pavement performance. Rigid pavements are recorded to provide resilience to flood hazard in literature but knowledge about its behavior and response to flood impact is currently scarce. The objective of this study is to investigate flood impact on concrete pavement performance examining case studies of Jointed Plain Concrete Pavement (JPCP) road classes in Ontario. The AASHTOWare Pavement ME was employed to simulate JPCP performance under climate-induced flood scenarios using a conservative Representative Concentration Pathway (RCP) of 4.5W/m2. Typical municipal JPCP collector and arterial road classes were chosen and modelled. While percentage change in faulting performance was considered, overall flood damage was based on relative change in International Roughness Index (IRI) under flood conditions. Results indicated lower damage ratios and pavement life loss in arterial JPCP than collector JPCP. Generally, minor flood damages were observed across RCP 4.5 return periods and event cycles in the collector and arterial case studies when compared to previous flooded concrete pavement investigation. [ABSTRACT FROM AUTHOR]

The Mechanistic-Empirical Pavement Design Guide (MEPDG) has been employed by agencies as an innovative method for pavement design since the National Cooperative Highway Research Program (NCHRP) Project 1-37A was implemented in 2004. Over the years, the MEPDG has evolved into the AASHTOWare Pavement ME Design software (AASHTOWare®). Local calibration of the performance models in the AASHTOWare® is a crucial and challenging task to improve the effectiveness of its application. The accuracy of the calibration depends on efficient methods and validation processes. This paper aims at developing local calibration methods for joint faulting prediction model of Jointed Plain Concrete Pavement (JPCP). This study not only focuses on improving the prediction accuracy of the joint faulting model but also demonstrating the various optimisation procedures in detail. A total of 27 representative JPCP sections were used in the processes of calibration. Three optimisation approaches were used: (1) One-At-a-Time (OAT) through the trial-and-error procedure, (2) generalised reduced gradient (GRG) using MS Excel® Solver, and (3) Levenberg-Marquardt Algorithm (LMA) fitting the functions. The prediction accuracy of local models was improved as compared with the global ones. Average Bias (AB) reduced from 0.3083 to 0.0578, and Standard Error of the Estimate (SEE) reduced from 0.3345 to 0.1912. Among the three local calibration approaches, approach 2 and approach 3 had more significant improvement on results than approach 1. Finally, the integral procedures were provided for local calibration in Ontario. [ABSTRACT FROM AUTHOR]

The simulation model used in this study is based on a construction project in Taiwan. In this study, STROBOSCOPE and EZStrobe were used as discrete-event simulation software to assess the potential risk of the construction in terms of time and cost. The construction process, the unit cost of the resources, and the operation time of each activity were modelled based on the actual construction procedure. A total of 30 replications was required for each scenario. Scenarios with real-world data inputs and eight other models were simulated using the software. The best scenario with the lowest cost and competitive time was selected as the base model for a sensitivity analysis. During the Sensitivity Analysis, the best model 8-R was generated by changing the number of labourers to 13 and Excavators to 3. Compared to the real-world project, the total costs were reduced by 11% and the total time was reduced by 58%. Moreover, the result of risk analysis based on scenario 8-R demonstrated that using a number of labourers, trucks, excavators, rollers, millers, and pavers less than the quantities that were used in the real-world data, the associated risk in term of cost and time will exceed the real-world project cost. [ABSTRACT FROM AUTHOR]

This paper presents a novel diagnostic model for evaluating the damage condition of a cement-stabilised base course using a T-S fuzzy neural network (FNN). An evaluation criterion for core damage rating, base core condition index (BCCI), was established based on the distress features observed in 369 core samples that had been collected from asphalt concrete pavements with cement-stabilised base courses. The core samples of cement-stabilised macadam (CSM) were classified into five levels according to the evaluation criterion. Ten parameters were chosen as inputs to establish non-linear mapping relationships in an FNN model. These input parameters include pavement distresses' characteristics (crack depth, breadth and lumpiness), Pavement Surface Condition Index (PCI), Riding Quality Index (RQI), Pavement Structure Strength Index (PSSI), Cumulative Equivalent Single Axle Loads (ESALs), thickness of asphalt concrete (AC) layers, annual temperature difference and average annual precipitation. Out of the 369 samples, 169 field cores were used in the FNN model for recursive training, and the parameters for the neural network structure were optimised until the errors between the network outputs and the expected outputs were minimised. The established FNN model was then used for the calculations of predicted quantitative results for remaining sections. The calculation results showed the logical reasoning capability of the T-S fuzzy system and the quantitative data processing capability of the neural network (NN). The comparisons between the objectively predicted results with the subjectively evaluated scores of the testing samples showed a prediction accuracy of 88.4%. The objectively predicted results calculated by the FNN model were also compared with the measurements taken using a Ground Penetrating Radar (GPR). The two groups of results showed reasonable similarity, which again indicated the effectiveness of the developed FNN method. [ABSTRACT FROM AUTHOR]

Precast concrete inlay panels (PCIPs) are a new rapid repair technique developed to address deep-seated rutting issues in asphalt pavements. Providing a uniform, stable support layer for precast concrete pavement is critical to its performance, and constructibility of this support is a key factor in the feasibility of PCIPs as an overnight repair technique. Three methods of PCIP support (asphalt supported, grade supported, and grout supported) were developed, designed, and constructed in a trial installation in Ontario, Canada. An analytic hierarchy process (AHP) analysis was performed to evaluate the performance of the options based on four construction-related criteria: cost, installation rate, repeatability, and resiliency. Input from the construction contractor and the Ministry of Transportation of Ontario was considered. This paper describes the support options, trial construction operations, and AHP evaluation. The results indicate that the grout-supported condition is most favorable and is recommended for future applications of PCIP for conditions similar to the trial section. [ABSTRACT FROM AUTHOR]

Existing performance models developed for interurban pavements are not applicable to urban pavements due to differences in traffic demands and deterioration trends. The objective of the study was to develop performance models for the management of urban pavement networks. Markov chains and Monte Carlo simulation were applied to account for the probabilistic nature of pavements deterioration over time, using data collected in the field. One of the advantages of this methodology is that it can be used by local agencies with scarce technical resources and historical data. Eight performance models were developed and successfully validated for asphalt and concrete pavements in humid, dry and Mediterranean climates with different functional hierarchies. The resulting models evidence the impact of design, traffic demand, climate and construction standards on urban pavements performance. Predicted service life of asphalt and concrete pavements in primary networks are consistent with design standards. However, pavements in secondary and local networks present shorter and longer service life compared to design life, respectively. Climate is a relevant factor for asphalt pavements, where higher deterioration was observed compared to that expected. Opposite to this, no relevant differences between design and performance can be attributed to climate in concrete pavements. [ABSTRACT FROM AUTHOR]

Protecting the pavement subgrade to increase the service life of road pavements is an aspect currently being explored. Several alternative pavement subbase materials are being considered, including Lightweight Cellular Concrete (LCC). Due to its lower weight, LCC incorporating industrial by-product, making it sustainable, and ease of use amongst other benefits, is seen as a potential candidate. This paper reports reviewing the potential application of LCC within the pavement structure with a specific application as a subbase. It examines the various properties such as modulus of elasticity, compressive and tensile strength, Water absorption, and freeze-thaw resistance necessary for pavement application. It also assesses its use in the field in Canada considering the design methods utilized. Some limitations and gaps for LCC application in pavements are also established and recommendations on how to further its use and performance. This review concludes that LCC possesses potential as a pavement subbase alternative; however, other mechanical properties like LCC's fatigue life is essential. A comparative field study is also recommended to monitor actual performance and various fact ors on performance. [ABSTRACT FROM AUTHOR]

Pervious concrete pavement can effectively reduce both the volume of water and the concentration of many sediment-associated contaminants in urban runoff. However, chloride from road salt is recognized as a threat to surface and groundwater resources because it is a conservative ion and does not readily bind to soil particles. To better understand and manage water resources in urban environments experiencing annual freeze-thaw cycles, this study examines the impact of road salt (sodium chloride) and sand applications on water and chloride movement in pervious concrete structures in a laboratory setting. Water movement and salt retention were characterized within pervious concrete slabs under frozen and thawed conditions. Laboratory experiments were repeated using both brine (23% salt solution) and fresh water as well as varying additions of sand (typical of winter sand application rates in Canada) to provide a range of temperatures experienced in cold-climate urban environments. Performance testing (via infiltration capacity) was conducted to assess the suitability of pervious concrete in climates where road sand and salt application is necessary. For all experimental conditions studied, chloride was rapidly transported through the pervious concrete. The complete freezing of pore water throughout the concrete slab reduced water and salt movement within the concrete matrix, while sand application reduced water movement through pores and delayed peak flow. The infiltration capacity of the pervious concrete structures, as tested, exceeds the probable maximum water loading rate that will be encountered in Southern Ontario, Canada, with or without sand, frozen or unfrozen. From a groundwater management and source water protection perspective, the data indicate that pervious concrete pavement structures may contribute to chloride contamination of groundwater if used in salt vulnerable areas and groundwater recharge zones. [ABSTRACT FROM AUTHOR]

Extremely low temperatures and freeze-thaw cycles cause premature cracking and low pavement bearing capacity. However, insulation layers could influence the extent of the temperature on pavements. This study focused on understanding the thermal behavior of lightweight cellular concrete (LCC) as an insulating subbase layer to protect the subgrade in pavements. The thermal performance was compared to a Control with Canada's conventional unbound subbase pavement structure. Empirical statistical temperature prediction models were developed based on two years of field data obtained from an instrumented test road in Waterloo, Ontario, Canada. The regression models were based on the most important factor, ambient temperature. This was determined by using a Generalized Addictive Model assessment process. Hourly pavement temperature data across the four seasons in Canada were studied. The effect of daily cooling and heating on pavement layer temperature was also evaluated. Results revealed that a 200 mm thick LCC subbase layer with a density of 400 to 475 kg/m3 could prevent the subgrade directly beneath it from freezing during harsh winters. Thicknesses equal to or >350 mm could be even more beneficial in alleviating the possibility of a frozen subbase and subgrade. There were 70 freeze-thaw cycles recorded in the subgrade of the conventional pavement, but none in the >250 mm LCC pavement portion. When the temperature models were validated using 13 months of data, satisfactory results were obtained. This study enables the prediction of the thermal behavior of LCC subbase pavements for future applications. • The possibility of mitigating the effect of frost action on the pavement structure, especially the subgrade is investigated • An insulation subbase layer of three low-density Lightweight Cellular Concrete (LCC) is employed as subgrade protection • The temperature profile within the pavement structure and the number of freeze-thaw cycles are monitored • Prevention of freeze-thaw cycling and frost heaving by insulation is attainable and would mitigate early pavement failure • Empirical statistical temperature models are proposed for predicting LCC-insulated pavement temperature in cold regions [ABSTRACT FROM AUTHOR]

Currently, mining is moving from open-pit to underground mining in order to improve its sustainability and as a result, a considerable amount of new concrete pavements are being constructed and maintained inside underground tunnels. Overall, productivity in the construction sector progresses at a much slower pace compared with other industries, and often well below the required pace for mining operations. Portland cement concrete is the most widely-used construction material in underground mining pavement due to its high performance; however, its traditional construction process and required curing period before opening to traffic result in an extended duration for project delivery. The above condition can have negative consequences, including cost overruns, increased risks, and more environmental impacts. An innovative approach to accelerate project delivery is the methodology known as Accelerated Construction. It integrates various techniques and technologies to reduce construction time and user impacts while enhancing and maintaining the safety and quality of the projects. However, no general definition of Accelerated Construction exists which considers its development and application across different kinds of infrastructure. The objective of this article is to identify and describe the Accelerated Construction techniques related to Portland cement concrete, and through the use of stochastic simulation models, compare, analyze, and define the advantages and benefits of this new approach over traditional techniques in the context of underground mining pavements. This paper is a significant contribution to the state-of-the-art providing a generalized definition of Accelerated Construction techniques; at the same time, the paper demostrated that these techniques can be an efficient and effective alternative for underground mining projects, improving mining productivity and costs, and reducing environmental impacts. • Accelerated Construction can improve mining productivity. • Accelerated Construction can reduce the mining-industry environmental impact. • An integrated design-construction approach boosts Accelerated Construction benefits. [ABSTRACT FROM AUTHOR]