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South Dakota Department of Transportation
Project Synopsis
SD2005-07


Title: Evaluation of Recycled Portland Cement Concrete Pavements for Base Course and Gravel Cushion Material
Project Researcher: Allen Cooley, Burns Cooley Dennis, Inc
Project Manager: Daris Ormesher
Research Period: 5/15/2005 - 5/31/2007
Status: Approved
Cost: $100,000.00

Problem Statement:Recycling Portland cement concrete pavements as an aggregate for base course (flexible pavement) or cushion material (rigid pavement) can reduce the need for virgin materials and eliminates disposal issues. However, SDDOT has no specific guidelines or specifications developed for its use. Another concern is the long term effects on pavement performance. There is evidence the recycled concrete breaks down when subjected to water. Literature has indicated that recycled concrete breaks down, then reactivates the cement and fly ash, and essentially become a cement treated base. This deterioration may effect freeze-thaw durability or cause excessive leaching, both very undesirable. South Dakotas experience with cement treated bases has not been favorable. Results from laboratory tests indicate the recycled concrete would not meet all current SDDOT specifications for base course or gravel cushion. It is not known if SDDOTs current specifications are appropriate for recycled concrete.

Current specifications allow the use of recycled Portland cement concrete as a gravel cushion material under new PCC pavements. Supplemental specifications state: "Recycled Portland cement concrete pavement used as a granular base material shall not be used for Base Course, Salvaged Base Course, or in areas where drainage fabric, edge drains, or other similar drainage systems are present," effectively limiting use.

SDDOT needs to determine the appropriate material tests and construction requirements to ensure recycled concrete will produce a durable pavement base material. If it is determined that recycled concrete can be used with no detrimental effects, then guidelines and specifications for its use need to be developed. Research is needed to verify that the use of recycled concrete is advisable in this application and does not create issues with respect to pavement durability or performance.



Findings: Results from this study as well as the experiences of other agencies suggest that recycled portland cement concrete pavements are an acceptable alternative for granular pavement layers. The recycled concrete aggregates should meet the requirements of the Revised Sections 260 and 882 of the South Dakota Standard Specifications.

Research Objectives:
1  Determine if recycled concrete should be used as a base course or gravel cushion.
2  Develop materials guidelines and specifications for construction of pavements using recycled concrete for base course or gravel cushion.
3  Develop laboratory and field material testing requirements for recycled concrete.

Research Tasks:
1  Meet with the project's technical panel to review project scope and work plan.
2  Review current literature, including other state's experiences, regarding use of recycled concrete as a base course or gravel cushion.
3  Interview other states to evaluate their experiences using recycled concrete to include laboratory and field tests, pavement performance, training, costs etc. Prepare the interview questions to be approved by the technical panel.
4  Propose an accelerated testing protocol to determine freeze-thaw and leaching performance of recycled concrete base materials in pavement sections for panel approval.
5  Conduct accelerated laboratory testing to determine durability of recycled concrete as a base material.
6  Evaluate existing, at least 3, SDDOT pavement sections utilizing recycled concrete using field survey and sampling and laboratory tests.
7  Determine materials guidelines and specifications for construction of pavement sections using recycled concrete for base course and gravel cushion, if appropriate.
8  Recommend construction specifications and testing necessary to construct pavement sections utilizing recycled concrete.
9  Recommend practical guidelines and specification changes for panel approval which will optimize the use of recycled concrete materials as base course or gravel cushion.
10  Prepare a final report and executive summary of the research methodology, findings, conclusions, and recommendations.
11  Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.

Documents Available:
SD2005-07_FINAL_REPORT.PDF
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