TYPICAL JPCP PAVEMENT (designed according to 1972-1989 versions AASHTO design guides)
To help highway managers and engineers implement the improved AASHTO 1998 Supplement Design Guide for Rigid Pavements, LTPP developed a software program called Rigid Pavement Design Software.
I am here to: - give you some background on it,- show you some of the useful features of the software,- show you how to use it,- and point out some of the benefits you will derive by using it. So lets start with a brief overview of what the rigid pavement design software is.The heart of the software is a Microsoft Excel spreadsheet.
It is a design tool that will walk you through the design and analysis procedures of the 1998 Supplement to the AASHTO guide.
The spreadsheet contains separate sheets that you can use to determine:-- accumulated traffic loadings,-- seasonally adjusted k values,-- adjusted k-value for depth to rigid layer,and to perform corner break and faulting checks.
Why is a new design procedure and accompanying design software tool needed?
The AASHTO Design Guide was first issued in 1961.It has been revised and expanded many times.The latest version is the 1993 Guide that includes the overlay design procedure.However the procedure for rigid pavement design is identical in both the 1986 and 1993 guides.Indeed the 1986 guide is the latest and most commonly used guide for rigid pavement design.
For consistency and to avoid confusion, note that when I refer to the 1986 AASHTO procedure, we are talking about the rigid pavement design used in both the 1986 and 1993 design guides.ART-- the AASHTO Road Test -- was conducted over 2 years between 1958 and 1960.
This is a photo of Loop 1 of ART. It was left in place after the end of the Test in 1960. All other loops became part of the traffic lanes of Interstate 80 near Ottawa, Illinois (100 miles West of Chicago).
ART is the largest full-scale pavement test site ever constructed and conducted. It is the basis of the AASHTO Design Guide.This photo shows a typical JPCP pavement designed according to the 1972-1986 versions of the design guide.
Over time and under heavy traffic conditions:
(1) extensive pumping and joint faulting, and eventually, excessive roughness occurs due to inadequate load transfer at joints (no dowel bars).(2) Erosion of the treated base course along the shoulder also occurs, creating a funnel for the infiltration of water.(3) transverse and corner cracking occurs due to insufficient slab thickness in the truck lane.