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Title:Review of Improved Subgrade and Stabilized Subbases to Evaluate Performance of Concrete Pavements
Author(s):Qamhia, Issam I. A.; Tutumluer, Erol
Subject(s):Concrete Pavements
Daylighted Subbase
Granular Subbase
Geotextile
Separation
Filtration
Stability
Drainability
Durability
Aggregate Quality
Abstract:This report presents findings on the evaluation of foundation layers under concrete pavements in the state of Illinois. It also provides recommendations and scenarios where unbound granular layers can be safely used under concrete pavements as economical and well-performing subbase layers. The current practice and mechanistic design methods for constructing concrete pavements in Illinois was first evaluated, including historical studies that led to the current design procedures and policies. The performance of concrete pavements with unbound granular layers in Illinois were then evaluated, and several case studies of well-performing concrete pavements with granular subbases, high traffic levels, and low distress levels and severity were realized. Next, the practices of surrounding states were evaluated, and several Midwest states, i.e., Wisconsin, Minnesota, Iowa, and Michigan, were found to regularly use unbound granular layers under concrete pavements with no issues. A literature review on the most recent requirements and recommendations for designing granular subbases under concrete pavements was then presented. It is concluded that subbase layers under concrete pavements are mainly used to provide uniform support and prevent pumping. Based on the case study evaluations and literature, a stable, drainable, and durable daylighted granular subbase design is recommended for traffic factors up to 10.0. Stability is ensured by limiting the ratio of gravel-to-sand fractions in the aggregate mix between 1.3 and 1.9. Drainability requirements can be met by limiting the percentage of fines passing the No. 200 sieve (0.075 mm) to 4% and by checking the quality of drainage is at least fair based on the time required to drain 50% of the water. Lastly, a geotextile fabric is recommended for use below the granular subbase for separation to ensure drainability throughout design life.
Issue Date:2021-05
Publisher:Illinois Center for Transportation/Illinois Department of Transportation
Citation Info:Qamhia, Issam I. A., and Erol Tutumluer. 2021. Review of Improved Subgrade and Stabilized Subbases to Evaluate Performance of Concrete Pavements. A report of the findings of ICT-R27-193-5. Illinois Center for Transportation Series No. 21-016. Research Report No. FHWA-ICT-21-011. Illinois Center for Transportation, Rantoul, IL. https://doi.org/10.36501/0197-9191/21-016
Series/Report:FHWA-ICT-21-011
Genre:Technical Report
Type:Text
Language:English
URI:http://hdl.handle.net/2142/110003
ISSN:0197-9191
DOI:https://doi.org/10.36501/0197-9191/21-016
Sponsor:IDOT-ICT-193-5
Rights Information:No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161.
Date Available in IDEALS:2021-05-28


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