The National CP Tech Center (CP Tech Center) has published three new manuals covering different aspects of concrete practices. These publications are for use by industry professionals interested in the latest information on:
- Recycling of Aggregates
- Geotextile use in Pavements
- Constructing Concrete Overlays
All three reference works can now be accessed from the 3 CP Tech Center web pages:
1. Recycling Concrete Pavement Materials: A Practitioner’s Reference Guide
by Mark B. Snyder, Tara L. Cavalline, Gary Fick, Peter Taylor, Steve Klokke, and Jerod Gross
88 pages
Recycling concrete pavements has been a common practice for many years, dating back to at least the 1940s with the reconstruction of US Route 66 in Illinois when the existing pavement was recycled back into the new project. It is with renewed interest that public agencies are now more closely examining the opportunities for recycling concrete pavements.
One reason for considering recycling is the diminishing quantity of good natural materials. However, many states still have specification or policy restrictions that do not allow concrete pavements to be recycled and utilized to the extent that is possible. In addition, the contracting industry may overlook opportunities to use recycled concrete aggregates (RCAs) on projects due to a lack of familiarity with the technical requirements or an uncertainty of how RCAs will perform for a specific application.
This practitioner’s reference guide for recycling concrete pavement materials was developed as part of a Federal Highway Administration (FHWA) cooperative agreement to support more sustainable concrete pavement technical solutions.
For the PDF of “Recycling Concrete Pavement Materials: A Practitioner’s Reference Guide”, please go to: http://www.cptechcenter.org/technical-library/documents/RCA_practioner_guide_w_cvr.pdf
2. Performance Assessment of Nonwoven Geotextile Materials Used as the Separation Layer for Unbonded Concrete Overlays of Existing Concrete Pavements in the US
by Tom Cackler, Tom Burnham, and Dale Harrington
45 pages
Geotextile fabrics have been used by pavement engineers for many years as a separation layer between full-depth concrete pavements and stiff cement-treated bases. Because of that success, pavement engineers have recently been evaluating nonwoven geotextiles as an alternative to hot-mix asphalt (HMA) separation layers in unbonded concrete overlay applications.
This report:
- Summarizes the performance of unbonded concrete overlays constructed in the US since 2008 using geotextile separation layers
- Provides an overview of lessons learned
- Highlights ongoing efforts to optimize the design and construction requirements for the use of geotextile fabrics in concrete overlay applications
To obtain detailed performance information on overlays built with geotextile separation material, nine projects were identified. A summary for each case history is included in this report, followed by the conclusions.
After nearly 10 years of positive project performance, it was found that nonwoven geotextile fabric separation layers work very well when used on existing pavements that have received the appropriate level of pre-overlay repairs. The fabric acts as a separation material to prevent cracks and other distresses in the underlying pavement from compromising the performance of new unbonded jointed concrete overlays placed over existing jointed and continuously reinforced concrete pavements. The fabric has also been shown to provide sufficient drainage to unbonded concrete overlay systems.
It was also found that the use of geosynthetic fabrics as a separation layer can provide significant cost and time savings when compared to traditional asphalt separation layers. State highway agencies are engaged in continuing research efforts to optimize the use of geotextile fabric separation layers.
For the PDF of “Performance Assessment of Nonwoven Geotextile Materials Used as the Separation Layer for Unbonded Concrete Overlays of Existing Concrete Pavements in the US”, please go to: http://www.cptechcenter.org/technical-library/documents/US_geotextile_performance_w_cvr.pdf
3. Guide for the Development of Concrete Overlay Construction Documents
by Jerod Gross and Dale Harrington
46 pages
Concrete overlays have proven to be a successful and feasible preservation method providing additional life for a roadway pavement. To be successful, a thorough evaluation process is critical to choosing the proper overlay type.
The purpose of this document is to provide guidance for the development of a concrete overlay project. This guide includes essential items needed to design and construct successful concrete overlay projects:
- Examples of construction drawings
- Specification guidance
- Cost information
- Design lessons learned
This guide was developed as part of an FHWA cooperative agreement to support more sustainable concrete pavement technical solutions.
For the PDF of “Guide for the Development of Concrete Overlay Construction Documents”, please go to: http://www.cptechcenter.org/technical-library/documents/overlay_construction_doc_dev_guide_w_cvr.pdf