The City of Saskatoon (COS) manages diverse road infrastructure assets. Given the present day challenges of structurally upgrading in-service road infrastructure assets in diverse field state conditions, there is a need to incorporate new innovative materials, changing field state conditions, and mechanistic design methods in sustainable road rehabilitation decision making. The COS is faced with challenges including rising material and labour costs, budget shortfalls, depleting virgin aggregate sources in close proximity to the COS, and an increase in stockpiled asphalt and concrete rubble materials due to transportation infrastructure renewal.
As a result of the COS impact crushing program, a need to determine the design and performance properties of using recycled reclaimed asphalt concrete (RAP) rubble materials in urban pavement structures was established. RAP materials had never been used as a structural base layer in COS pavement structures because no material characterization had been conducted and there was no performance information with regards to their structural behaviour and field performance available. Other jurisdictions documented benefits of using recycled RAP in road structure include: reduced demand on depleting aggregate sources; reduced energy consumption; diversion of stockpiled RAP materials from landfills; and reduced overall handling and disposal costs. Given the amount of crushed RAP material available to the COS, it was determined there are potential benefits to implementing the use of recycled crushed RAP rubble in pavement structures, leading to the implementation of the “Green Street” Infrastructure Program.
The findings of this research indicate that RAP materials have improved mechanistic properties compared to conventional granular materials; therefore, RAP materials can be used as a base layer in a road structure. This research indicates that cement stabilization and cement with a slow setting (SS-1) emulsion stabilization improved the moisture susceptibility of well graded (GW) and open graded base course (OGBC) RAP materials. These findings demonstrated that RAP materials stabilized with cement and/or SS-1 emulsion can be used as a base layer in a pavement structure.
This research also found that the standard Proctor compaction method is not applicable for RAP materials to quantify moisture-density behaviour under compaction, due to the bound-nature of RAP aggregates, which are composed of asphalt and aggregate. California bearing ratio (CBR) values of Proctor-compacted RAP specimens did not accurately reflect field performance observations.
As part of the COS “Green Street” Infrastructure Program, two test sections using crushed GW RAP rubble materials as a base layer were constructed as part of this research and include Marquis Drive (eastbound lanes from Thatcher Avenue to Idylwyld Drive) and 8th Street East (westbound lanes from Boychuk Drive west 0.540 kilometers). Test sections were constructed by the City of Saskatoon with conventional construction equipment and showed structural improvement in structural performance and visual distresses. Using RAP materials as a base layer was economically feasible because the RAP material cost less than conventional virgin aggregate base materials.
This research demonstrates that processed and crushed RAP rubble materials are technically feasible to be used as a structural base layer in a recycled pavement structural system for urban road rehabilitation systems, and provide economic benefits over conventional granular base materials.
| Identifer | oai:union.ndltd.org:USASK/oai:ecommons.usask.ca:10388/ETD-2013-06-1151 |
| Date | 2013 June 1900 |
| Contributors | Berthelot, Curtis F. |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text, thesis |
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