Pavement structures in the northern united states, canada, scandinavia, and other seasonal frost areas of the world are subject to freezing in winter and thawing in spring. Most damage to pavements inseasonal frost areas occurs during the spring thaw and, to a lesserextent, during partial thaw periods in winter. To minimize damage, pavement engineers must be able to determine the structural capacityof road and airfield pavements during thawing periods. Four pavement test sections were built in the frost effects research facility atthe u.S. Army cold regions research and engineering laboratory in hanover, new hampshire, to study the performance of various pavement structures subjected to freeze-thaw cycling. The test sections consisted of asphalt concrete pavement over a clay subgrade, asphalt concrete over crushed gravel on a clay subgrade, asphalt concrete over 178 mm of crushed gravel and 203 mm of clean sand on a clay subgrade, and asphalt concrete over 254 mm of crushed gravel and 127 mm of clean sand on a clay subgrade. Thermocouples were embedded throughout the pavement structure and subgrade, and the pavement structure was subjected to several freeze-thaw cycles. Deflection measurements taken during the thawing periods at four locations in each test sectionused a dynatest falling-weight deflectometer (fwd) to validate existing back-calculation procedures for pavements subject to seasonal frost. Soon it became apparent that the back-calculation procedures had difficulties. Another study was initiated to determine if additional information pertaining to freeze-thaw cycling could be obtained from the fwd measurements. The results of the second study are presented. This paper appears in transportation research record no. 1286, Design and evaluation of rigid and flexible pavements 1990.
Samenvatting