There exists two factors to assist in deciding whether or not a municipality should expect to have a roadway management system, these being population size and road network size. A large population tends to contribute more vehicles to the roads, which leads to frequent maintenance needs and therefore requires a road management system. Municipalities with large road networks may choose to follow a road management guideline to optimize their maintenance schedules. But, in some cases, municipalities with only a few kilometers of roadway can play a vital role in the provincial road network, especially when those roads link important destinations. So, a few pertinent questions arise. Do population size and road network length determine whether a municipality or town adopts a road management system? How do municipalities with small population size and shorter road networks manage their roads? What can be the most feasible way for those municipalities to manage their roads? To answer these questions, a province-wide municipality staff survey was conducted in Newfoundland and Labrador (NL), Canada. Most of the municipalities in this province are sparsely populated, and the internal road networks are very small. The survey was conducted to determine the condition of the roadway assets in these small municipalities, the resources available, and the requirements of roadwork by transportation departments to do in order to improve their roads. This project was not a government-funded project, and there was no incentive for the participants. Therefore, participation was completely voluntary. The results provide significant information about roadway asset conditions and management systems in the municipalities.

Contributors:, Bernier A.

In the coming years, it is anticipated that the current Canadian climate will no longer be the norm, and temperatures will be increasingly different as a result of anthropogenic climate change. Increased greenhouse gas concentrations in the atmosphere are at the root of changing climate, which is only expected to worsen over time. Pavement performance models show that changing climate will result in accelerated pavement deterioration. To mitigate pavement deterioration, various adaptation strategies have been suggested in the recent literature. One of these adaptation strategies is upgrading the superpave asphalt binder grade. It is well known that asphalt binder is highly sensitive to climate factors such as temperature and percent sunshine. Hence, reviewing asphalt binder grade is a vital step, and that can help decelerate pavement deterioration. This study aims to understand the impact of climate change on existing flexible pavements and identify the appropriate binder grades necessary to accommodate these effects across Canada. To achieve this goal, the analysis was carried out in six phases. In the first phase, statistically downscaled climate change models were gathered from the Pacific Climate database. Then in the second phase, daily maximum and minimum temperatures and daily average precipitation data were extracted using a python code. In the third phase, the pavement materials, traffic, and structural data are collected from Long-term pavement performance (LTPP) database. In addition, hourly temperature and precipitation data were estimated using existing hourly data and state of the art estimation model for each day throughout the design period. Then in the fourth phase, the pavement performance was assessed using AASHTOware Mechanistic-Empirical (ME) Pavement Design. In the fifth phase, using the temperature data gathered from pacific climate, asphalt binder grades were determined for the future climate. Then in the final phase, the pavement performance is again determined with the proposed future asphalt binder grades. Comparing the pavement performance between base binder grade and the proposed future binder grade confirms the necessity of considering proposed asphalt binder grades for future climate.

Contributors: , Bernier A.

In recent years, average temperatures in Canada have been continuously increasing, owing to changes in the global climate. This can be attributed to a surge in the concentration of greenhouse gases in the atmosphere. Climate scientists predict the trend to further aggravate in the near future. Pavement performance models show that changing climate will result in accelerated pavement deterioration. To mitigate pavement deterioration, various adaptation strategies have been suggested in the recent literature. One of these adaptation strategies is upgrading the superpave asphalt binder grade. It is well known that asphalt binder is highly sensitive to climate factors such as temperature and percent sunshine. Hence, reviewing asphalt binder grade is a vital step, and that can help decelerate pavement deterioration. The goal of this research is to determine new asphalt binder grades across Canada based on the projected climate data. To achieve this goal, the analysis was carried out in four phases. In the first phase, statistically downscaled climate change models were gathered from the Climate Change model database. Then in the second phase, python code is written to extract the maximum and minimum temperatures from the climate change models for a particular location. Later in the third phase, from the extracted maximum and minimum temperature, average seven-day maximum pavement temperature and minimum pavement temperature are determined using the LTPP pavement temperature prediction model. Lastly, high-temperature grade (XX) and low temperature grade (YY) of an asphalt binder (PG XX – YY) are estimated using the average seven-day maximum and minimum pavement temperature respectively and tabulated in an easy-to-use format for application by the transportation agencies in Canada. Note this paper presents a very brief summary of this research project and five climate models used in the analysis. Finally, this paper also presents the revised asphalt binder grades for ten different locations, each from one of the provinces.

Contributors: , .

Now-a-days concrete pavements are gaining more and more importance to eliminate frequent maintenance of bituminous pavement, damaged by heavy commercial vehicles and moisture. Several types of plain concrete pavement are in use in various countries depending upon the climate, availability of materials, soil types, experience, and traffic. It is therefore necessary to improve the current pavement design with a sound analytical approach. To lower the cost of construction of concrete pavements, researchers came to a new type of concrete pavement construction named Two-Lift Concrete Pavement (TLCP). In this type of pavement construction, Pavement Quality Concrete (PQC) can be bonded to lean concrete (LC) when both layers are laid one after the other with two pavers (“fresh-on-fresh” or “wet-on-wet”). No analytical techniques are available to compute the stresses in TLCPs. To compute the stress in TLCP under various environmental and loading conditions, a finite-element programming software (ANSYS) is used. These stresses place an important role in determining the design of concrete pavements. To achieve this, a Central-Composite design with face-centered statistical design is utilised. In this design, statistical assumptions such as Normality, constant variance and Independence are checked and found that all assumptions are acceptable, but box-cox suggested to transform the model to square root. So, the model is transformed to square root form. The statistical model is validated using four random points and it is noticed that the model satisfies all the points. Conclusions are drawn from the interaction plots of the model. From the model, it is noticed that the factors such as temperature gradient over the depth of the slab and modulus of subgrade reaction are insignificant but when it interacts with other factor (PQC thickness and LC thickness), the interaction became highly significant.

Contributors: , .

On average, one tire per capita per year is generated in Canada as a waste tire, which either goes to landfill or stockpile. Researchers across the world are trying alternative uses of scrap tires. Among many civil engineering applications, roadway embankment construction using tire-derived aggregates (TDA) is the most popular and ecologically viable due to large amount of consumption of material in the embankment. However, its deformability/ compressibility under applied load is an important consideration for design of tire shred embankment. The mechanical behavior of tire shreds is dependent on stress levels, which shows nonlinear viscoelastic-plastic behaviour. There is a lack of quantitative information on the compressibility characteristics of tire shred embankments. In this study, the finite element (FE) method is applied to assess the compressibility of the tire shred embankment. Nowadays FE method is being increasingly used in deformation analysis of pavements. Linear and nonlinear compressibility analysis of tire shred embankment is performed, assuming a multilayer elastic-isotropic system. The results show that deflections of the road calculated from nonlinear elastic analysis are significantly higher than those calculated using linear elastic model. The analysis also shows that small size tire shreds (50 mm) experience less deflection compared to large size tire shreds (300 mm). Resulted deflections obtained from FE calculations are then compared with the results from an analysis using a multilayer computer software, KENLAYER, available in published literature. Finally, the paper presents the key features of tire compressibility of different sizes of tire shreds observed during the FE analysis.

Contributors: Reza A, Dhar A S.

On average, one tire per capita per year is generated in Canada as a waste tire, which either goes to landfill or stockpile. Researchers across the world are trying alternative uses of scrap tires. Among many civil engineering applications, roadway embankment construction using tire-derived aggregates (TDA) is the most popular and ecologically viable due to large amount of consumption of material in the embankment. However, its deformability/ compressibility under applied load is an important consideration for design of tire shred embankment. The mechanical behavior of tire shreds is dependent on stress levels, which shows nonlinear viscoelastic-plastic behaviour. There is a lack of quantitative information on the compressibility characteristics of tire shred embankments. In this study, the finite element (FE) method is applied to assess the compressibility of the tire shred embankment. Nowadays FE method is being increasingly used in deformation analysis of pavements. Linear and nonlinear compressibility analysis of tire shred embankment is performed, assuming a multilayer elastic-isotropic system. The results show that deflections of the road calculated from nonlinear elastic analysis are significantly higher than those calculated using linear elastic model. The analysis also shows that small size tire shreds (50 mm) experience less deflection compared to large size tire shreds (300 mm). Resulted deflections obtained from FE calculations are then compared with the results from an analysis using a multilayer computer software, KENLAYER, available in published literature. Finally, the paper presents the key features of tire compressibility of different sizes of tire shreds observed during the FE analysis.

Contributors: Reza A, Dhar A S.

Two factors may decide whether a municipality can expect to have a roadway management guideline. One is the population size, and another is the road network size within the municipality. A large population tends to contribute more vehicles to the roads, which leads to frequent maintenance needs and therefore requires a road management guideline. Municipalities with large road networks may follow a road management guideline. But in some cases, municipalities with only a few kilometers of roads can play vital roles, especially when those roads link important destinations. So, a few pertinent questions arise. Do population size and road network length determine whether a municipality or town adopts a road management system? How do municipalities with small population size and shorter road networks manage their roads? What can be the most feasible way for those municipalities to manage their roads? To find the answers to these questions, a province-wide municipality staff survey was conducted in Newfoundland and Labrador (NL), Canada. Most of the municipalities in this province are sparsely populated, and the internal road networks are very small. The survey was conducted to determine the condition of the roadway assets in these small municipalities, the resources available, and the requirements of work by transportation agencies to do in order to improve their roads. This project was not a government-funded project, and there was no incentive for the participants. Therefore, participation was completely voluntary. The results provide significant information about roadway asset conditions and management systems in the municipalities.

Contributors: , .

Inverted pavement system is an alternate form of pavement when compared to flexible pavement. This pavement system consists of a stabilized layer below an aggregate base with asphalt surfacing. In this study, the stabilized layer has been divided into a cemented base layer and a cemented sub-base layer. This research is aimed at evaluating the potential of a cement stabilized brick-fly ash mixture for the base, and only cement stabilized fly ash (no aggregate) for the sub-base layer of the pavement. Three different cement contents (3%, 6%, and 9%) were selected to find the optimal cement content for the base and sub-base layers of the pavement structure. Once the optimal moisture content for different compositions was ascertained, the strength (compressive and tensile), modulus, and durability parameters were evaluated at the laboratory scale. The optimal quantity of cement for the materials used in both layers for stabilization was determined based on the required strength and durability criteria. The optimal cement content for cement-brick-fly ash mixture used for the base layer of pavement was found to be 6%. Similarly, the optimal cement content for cement-fly ash mixture used for the sub-base layer of pavement was found to be 7%. Finally, the inverted pavement consisting of fly ash-based cemented layers is designed based on design on experiment using a centre composite design of response surface methodology. Eight factors were considered for determining the optimized solution under the constraints of minimum critical strains and the thickness of cement-treated pavement layers.

��DzԳٰ������ܳٴǰ���:��, Ashish P K, Kannelli V, , Tiwari D, Nagabhushana M N, Havanagi V G.

The inverted pavement system is a composition in which a weak layer is placed on a relatively strong stabilized base layer.  The base layer of the inverted pavement studied in this work is mostly a cement-treated layer with varied cement content depending on the unconfined compressive strength (UCS) criteria. Furthermore, in this research, the base layer of the present pavement system is designed with fly ash, aggregate, and treated with cement wherein the fly ash that has been used as the replacement of aggregate. The optimal cement content has been determined for the new aggregate blend considering strength and durability requirements of the blended mix. The pavement has been designed as per Indian specification, and a test track has been constructed for 0.5 million standard axle traffic. The performance of test section has been evaluated using Falling Weight Deflectometer (FWD) at the base level, Benkelman Beam Deflection (BBD) at surface level and Accelerated Loading Test (ALT) by actual loading through a standard axle truck traveling back and forth on the test track. The evaluation of pavement in terms of rutting and fatigue of the surface layer has been monitored to determine the performance of the pavement. The post-failure evaluation of the test track has been done using Plate Load Test (PLT), Dynamic Cone Penetration (DCP) test, and Ultrasonic Pulse Velocity (UPV) test to ascertain the distress caused.

��DzԳٰ������ܳٴǰ���:��, Nagabhushana M N, , Tiwari D, Vittal U K G, Bazan C.

Traffic volume is a primary design parameter in pavement design. This study focuses on evaluating the variability between field and projected traffic volume and its impact on asphalt pavement performance for various road sections in Canada. In this study, the Annual Average Daily Truck Traffic (AADTT) is considered as traffic volume. Baseline traffic is projected from the baseline year to the final year of field observation following the no-growth, linear growth, or compound growth technique allocated for different vehicle classes on the LTPP database. Projected and observed traffic was compared to observe variability. To determine asphalt pavement performance for field and projected traffic volume, the AASHTOware pavement mechanistic-empirical pavement design tool was used. To incorporate field observation traffic data in AASHTOware, the traffic growth rate is evaluated from the same projection technique used in projected traffic. The traffic growth rate is evaluated in such a way that projected traffic volume matches with field observation traffic. Traffic volume of baseline year with LTPP growth rate and evaluated growth rates are inputted into AASHTOware in case of projected traffic and field observation traffic, respectively. Other fundamental inputs in the MEPDG program are kept constant for individual sections. The results show that the projected traffic volume has a significant influence on pavement performance in terms of asphalt concrete (AC) bottom-up fatigue cracking, AC rutting, and total rutting on different roads. Equivalent AC layer thickness was also estimated in respect of observed traffic to minimize the additional impact of pavement distresses.

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