Toward effective use of road foundation materials in urban pavements

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ConferenceAnnual Conference of the Transportation Association of Canada: 01 October 2000, Edmonton, Alberta
Pages115; # of pages: 15
Subjectroad foundation materials, sub-base layers, characterization techniques, performance, mechanical response, traffice, environmental condition, resilient modulus, unbound aggregate, factorial design, moisture content, deviator stress; Roads/Pavement; Roads
AbstractThe nature of road foundation materials plays a significant role in defining pavement behaviour under traffic loading. Currently, however, this role and its impact on road performance are not well established. This calls for the need to develop adequate characterization techniques for road materials. The requirement to consider relevant performance indicator(s) necessitates in the beginning reliance on a mechanical response. Mechanical responses are usually based on external loading conditions. In the case of a pavement structure, this translates into traffic and environmental conditions and constitutes an important input to the pavement design/rehabilitation process.This paper presents recent developments in the area of road foundation materials characterization that is currently being pursued at NRC's Institute for Research in Construction. A state-of-the-art laboratory facility was designed and built to develop effective measures to guard against road deterioration in the case of inadequate structural support provided to the asphalt surface. Using this facility, a silty sand material representing a typical subgrade and an unbound aggregate material commonly used in base and sub-base road layers were tested under various load and physical conditions.Results obtained in the form of resilient moduli of the tested materials were analyzed using statistical techniques. The results highlighted the well-known need to control compaction quality of these road materials to effectively reduce the potential for premature failure. Furthermore, the results suggest the need for putting more emphasis on moisture effects than currently being considered. Current practice focuses on obtaining the highest possible percentage of relative field density with less emphasis being placed on controlling field moisture content. The results obtained from the mechanical test on both investigated materials show a significant drop in strength for an increase in moisture within commonly accepted ranges. These findings advocate the need to revisit the way that road foundation materials are characterized and the implication(s) that this may have on the design and rehabilitation of pavements.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number43924
NPARC number20331207
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Record identifier562515d1-22b3-4909-9da3-2922bee456e2
Record created2012-07-18
Record modified2016-05-09
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