Overview of Design
A recent survey on CRCP design practices in the US(1)Summary of CRCP Design and Construction Practices in the US (CRSI Research Series No. 8) indicated that most States that commonly use this pavement type use the AASHTO design procedure.(2)Guide for Design of Pavement Structures (AASHTO 86/93) One exception is Illinois, which uses a modified version of this method. While there are differences in the overlay design, the core of the pavement design procedures found in both the 1986 and 1993 editions is the same. Therefore, the guidelines presented in this website refer to this method as the “AASHTO-86/93” design procedure.
Since the development of the AASHTO-86/93 design procedures, a number of new findings have been reported based on research conducted around the world. Some of these findings include improved practices based on a FHWA research study where CRCP sections in several states were evaluated.(3)Performance of CRCP – Volume I: Summary of Practice and Annotated Bibliography (FHWA-RD-94-178)(4)Performance of CRCP – Volume II: Field Investigations of CRCP (FHWA-RD-94-179)(5)Performance of CRCP – Volume III: Analysis and Evaluation of Field Test Data (FHWA-RD-94-180)(6)Performance of CRCP – Volume IV: Resurfacings for CRCPs (FHWA-RD-98-100)(7)Performance of CRCP – Volume V: Maintenance and Repair of CRCP (FHWA-RD-98-101)(8)Performance of CRCP – Volume VI: CRCP Design, Construction, and Performance (FHWA-RD-97-151)(9)Performance of CRCP – Volume VII: Summary (FHWA-RD-98-102) Additional findings have been reported from evaluation of sections in the LTPP database.(10)Preliminary Evaluation of LTPP CRCP Test Sections (FHWA-RD-99-086)(11)Mechanistic Analysis of Factors Leading to Punchout Development for Improved CRCP Design Procedures Other experimental and field studies performed by individual States and around the world have also contributed to updates in CRCP design.(12)CRCP in Virginia – Lessons Learned(13)The Construction and Performance of CRCP with Flexarm(14)Concrete Pavement Design and Construction Practices by the Texas DOT It is important that pavement design engineers in the US are aware of such findings, as they may very likely have an impact on the performance of CRCP that can translate into cost-effective pavement solutions.
Designing a CRCP involves dimensioning the different geometric pavement features such as thickness, longitudinal and transverse reinforcement, construction joints, slab width, shoulders, and pavement transitions based on site-specific traffic, climatic, and foundation parameters. The designer selects pavement designs that will be suitable to achieve the desired performance level for the design period selected. As in all pavement designs, the goal is to use locally available materials to the greatest extent possible, but without compromising pavement performance.
The crack spacing, crack width, steel stress, and bond development length generated as a function of reinforcement restraint and climatic conditions each affect the CRCP structural integrity in the long term. It is important that precautions are taken during the CRCP design, materials selection, and construction process so that a crack pattern develops that minimizes development of pavement distresses.
It should also be noted that many of these design aspects described on this website are common to all concrete pavements – not just CRCP. As a result, and for brevity, some aspects of concrete pavement design will not be expanded upon herein. Instead, guidance should be sought from the appropriate design references such as the AASHTO-86/93 Guide.
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