The Saskatchewan, Canada, Department of Highways and Transportation is investigating alternative recycling and strengthening systems for inservice thin granular pavements. This research is being performed to improve the granular pavement structural integrity and to reduce the dependence on new source aggregates. A pilot project investigated the mechanistic-climatic laboratory characterization of materials used to construct test sections on Control Section Highway 15-11 (C.S. 15-11). This research demonstrated the use of ground-penetrating radar and falling weight deflection measurements to select uniform field test section locations. In situ recycled granular base was sampled and found to be a typical thin granular pavement requiring strengthening because it is relatively high in fine sand fraction and has a high portion of intermediate plastic clay fines. These two properties are known to cause marginal performance of granular bases in the field. This research showed that cement and bitu-minous stabilization significantly improved the mechanistic primary response and climatic durability properties of marginal granular base materials. However, it was found that the asphalt emulsion with cement stabilization showed the highest performance improvement. It also was found that the addition of cement to emulsified and foamed asphalt stabilization systems significantly improved the mechanistic-climatic durability of the marginal granular base aggregate. This study demonstrated the rapid triaxial tester to be a pragmatic and cost-efficient methodology to characterize the mechanistic constitutive relations of granular base materials for performing mechanistic road structural modeling.

Given the renewal of urban infrastructure and the increased costs of landfilling concrete rubble materials, opportunities exist to optimize the reclamation and recycling of portland cement concrete (PCC) and hot-mix asphalt concrete (HMAC) rubble through their innovative use in road rehabilitation. The primary objective of this study was to demonstrate the ability to reclaim, process, and recycle stockpiled concrete materials to provide improved structural mechanistic–climatic material properties and to meet or exceed the mechanical properties of conventional granular road materials. This research was based on advancements made in 2009 as part of the Green Streets Infrastructure Program in the city of Saskatoon, Saskatchewan, Canada. A second objective of this research was to pilot the field application of reclaimed and recycled HMAC and PCC rubble in typical urban road reconstruction applications. Recycled HMAC and PCC materials were used in the pilot reconstruction of a road that was exhibiting substructure moisture problems and structural failure. This study showed that recycled HMAC and PCC rubble materials could be processed to achieve mechanistic laboratory properties that exceeded those of conventional granular-based materials. This study also demonstrated efficient constructability and high end-product structural asset value of a typical rehabilitated urban road structure test section in the city of Saskatoon by using recycled HMAC and PCC rubble. On the basis on these findings, the use of quality processed HMAC and PCC rubble materials for road reconstruction was found to be a technical and environmentally sustainable solution.

Different types of intelligent rollover system deployed by road agencies across North America are investigated. The importance of weight is addressed for maximum effectiveness of rollover warning messages for commercial vehicles in a potential rollover situation on sharp curves or exit ramps. The type of information that may be used to activate a rollover is discussed to analyze the number of correctly warned vehicles compared with the number of false warnings generated by the rollover warning system. A case study of the effectiveness of an intelligent rollover system is presented. On the basis of this case study, it was found that speed-based rollover warning systems generated anywhere from 44 percent to 49 percent more false rollover warnings for commercial vehicles than did rollover warning systems that employed weight information in the rollover decision criteria.

Increasing commercial traffic over recent years is inflicting increased damage to roadways. As a result, road engineers are adopting more mechanistic performance-based road-modeling techniques to assist in the design, construction, and preservation of road assets. One such common mechanistic analysis technique is dynamic deflection pavement response induced under typical commercial truck loading. This paper presents an investigation of piezoelectric axle sensors as a possible tool for obtaining dynamic pavement deflection data under commercial truck loadings. One of the primary benefits to using piezoelectric axle sensors is that there are thousands of piezoelectric sensors already installed in roads world wide currently measuring the dynamic weights of commercial vehicles. Specifically, this research investigated the potential to use several different types and orientations of commercially available piezoelectric axle sensors to measure pavement deflection response under heavy truck loading. This research found that data from certain piezoelectric sensors and configurations could potentially predict deflection characteristics of a typical flexible pavement system. Based on these findings, there is the potential to use piezoelectric axle sensors for primary response modeling of road structures.Key words: piezoelectric sensors, deflection bowl, weigh-in-motion, mechanistic road modeling.

The province of Saskatchewan has the largest number of public roads per capita in Canada and one of the largest in the world. Over the past decade, pressures on the road network have increased, resulting in accelerated road damage and increased demand to upgrade portions of the highway network. To address transportation infrastructure sustainability issues, Saskatchewan Highways and Transportation (DHT) and Pavement Scientific International, Inc., are researching more cost-effective methods. The research work involves evaluating the technical and economic feasibility of undertaking alternative road construction techniques. A critical component of this research effort is to evaluate the economic feasibility associated with different road construction techniques. The ability to perform whole-life economic analysis associated with long-term infrastructure assets is important to long-term sustainability. By comparing the present value of initial construction and future preservation costs across different road structures and technologies, an accurate assessment of construction and design options is achievable. On the basis of performance predictions and projected structural performance, resource allocation can be optimized more reliably across limited resources and alternative road strengthening systems, providing technically sound solutions that are more economically attractive. With an ability to predict whole life-cycle performance on the basis of future maintenance treatments, road managers can more reliably assess alternative surfacing and structural preservation strategies. The primary focus of this paper is to demonstrate the economic considerations undertaken in evaluating alternative road design and construction methods. This longer-term evaluation approach allows strategic investments in highway infrastructure and allows DHT and other agencies to consider innovative road structural rehabilitation and management strategies more effectively.

The purpose of this research was to determine how asphalt cement binder types influence the mechanical behaviour of hot mix asphalt concrete mixes. This research employed triaxial frequency sweep characterization of a typical City of Saskatoon Hot Mix Type A2 and a typical Saskatchewan Ministry of Highways and Infrastructure Hot Mix Type 70 across a range of triaxial load frequencies and stress states representative of Saskatchewan field state conditions. The asphaltic mixes were evaluated across four asphalt cement binder types typically employed by Saskatchewan road agencies. Based on the findings of this study, the mechanical behaviour of both asphalt mixes evaluated were found to be highly sensitive to load rate, stress state, as well as asphaltic binder type. It was concluded that load rate, field stress state, and asphalt binder type should be incorporated into the structural design of hot mix asphalt concrete pavements to ensure adequate mix performance, particularly when placed in severe field conditions.

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