Establishing layer coefficients for CTB, PMBB, and RAP.

Edwards, Amy; Huddleston, Jim; Moore, Lucinda; Gower, Jeff

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Establishing layer coefficients for CTB, PMBB, and RAP.

1991-09-01
By Edwards, Amy ; Huddleston, Jim ; Moore, Lucinda ; ...

File Language:

English

Details

Creators:

Edwards, Amy ; Huddleston, Jim ; Moore, Lucinda ; Gower, Jeff
Corporate Creators:

Oregon State Highway Division. Pavement Unit
Corporate Contributors:

Oregon. Department of Transportation. Materials and Research Section
Subject/TRT Terms:

Aggregate Mixtures Asphalt Asphalt Pavements Base Course (Pavements) Base Subases Bituminous Bases Cement Cement Treated Soils Laboratory Tests Layer Coefficient Layer Coefficient (Pavements) Pavement Design Plant Mix Recycled Recycled Materials Treated
Publication/ Report Number:

FHWA-OR-RD-92-04
Resource Type:

Tech Report
Geographical Coverage:

Oregon
Corporate Publisher:

Oregon State Highway Division. Pavement Unit
Abstract:

In 1988, the Oregon State Highway Division adopted the 1986 AASHTO guide for pavement thickness design. Currently the OSHD uses a layer coefficient of .22 to .24 for cement treated base (CTB), and .32 for plant mix bituminous base (PMBB). Recycled asphalt pavement grindings (RAP) have been given the same layer coefficient as that used for aggregate base. This study was conducted to determine more specific values which take into account local materials and specifications. Through the use of laboratory triaxial, diametral, and unconfined compressive strength testing equipment, the strength properties of the CTB, PMBB, and RAP were characterized and correlated to AASHTO layer coefficients. The results of the testing for CTB were modified to take into account the new OSHD specification and the unrecoverable cores. The modified data resulted in project average layer coefficients for CTB ranging from .21 to .30. The PMBB project averages for layer coefficients ranged from .3 to .47. The range in these values is considerable. The current design practice of using layer coefficients of .22 to .24 for CTB and .32 for PMBB will be continued until additional data and specification changes are made to justify a change. The use of RAP in lieu of untreated aggregate base appears to be a good alternate on some projects.
Format:

PDF
Funding:

HPR 5282
Collection(s):

US Transportation Collection
Main Document Checksum:

urn:sha256:579c5c766683a48d63f046a2a3e733ec958e7fd25ee76c82ec31fb9a161d7e17
Download URL:

https://rosap.ntl.bts.gov/view/dot/22926/dot_22926_DS1.pdf
File Type:

[PDF - 2.00 MB ]

File Language:

English

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