Title: DESIGN OF FULL-DEPTH ASPHALT AIRFIELD PAVEMENTS
Abstract: A theoretical design procedure for Full-Depth asphalt concrete airfield pavements is presented. The design is based upon the use of multilayered elastic theory and utilizes the concept of limiting strains to prevent repetitive permanent deformation and/or shear failure within the subgrade layer and repetitive load cracking within the asphalt bound layer. Development of the allowable strain levels for both failure modes are presented. The method utilized to obtain limiting strains associated with the subgrade was to theoretically analyze (granular Base) pavement thickness requirements as defined by the newly revised U.S.A.C.E. thickness design method. These revisions are related to changes in thickness requirments as well as load repetition effect upon thickness from the previous method. Results indicate that a limiting vertical strain of 1460 microinches per inch, evaluated at a limiting asphalt concerete modulus of 100,000 psi, is capable of withstanding 1,000,000 strain repetitions. Limiting strains associated with the asphalt bound layer have been established from results developed by Kingham from Full-Depth asphalt concrete pavements of the ASSHO Road Test study. An allowable tensile strain of 76 microinches per inch will allow 1,000,000 repetitions when evaluated at a critical asphalt concrete modulus of 1,450,000 psi. Because of the extreme dependency of the stress and strain distributive characteristics of thick Full-Depth asphalt pavements to temperature, monthly cumulative damage techniques were used to develop thickness adjustment factors to adjust thickness requirements for both failure modes due to differeing environments. The limiting or critical modulus utilized in the vertical subgrade strain analysis is related to an average annual air temperature of 75 degrees F. For cooler environments, a thickness reduction may be used. The maximum suggested reduction proposed is 10 percent for environments having a 50 degree F. average annual air temperature. Maximum percentage thickness reductions of 13 percent are suggested for the tensile asphalt concrete strain analysis. This is equivalent to a maximum thickness adjustment factor value of 1.00 at 40 degrees F. (average annual air temperature) and a minimum thickness adjustment factor value of 0.87 for 60 degree F. environmentas. /AUTHOR/
Publication Year: 1972
Publication Date: 1972-09-01
Language: en
Type: article
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Cited By Count: 33
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