A design method of perpetual flexible pavement in Israel

Abstract

A perpetual flexible pavement is defined as hot mix asphalt (HMA) pavement, designed and built to last longer than 50 years without requiring major structural rehabilitation or reconstruction. It may only need periodic surface renewal when the distresses have reached unacceptable levels. The design methods currently used in the USA and other countries are not adequate for the traffic and climatic conditions in Israel. An adaptation of these methods, for Israeli traffic and environmental conditions is presented. The total perpetual pavement thickness is calculating using the Israeli design method, which can handle a wide variety of load levels. The HMA layers thickness is determined as the minimum thickness at which the tensile strain at the bottom of the HMA layer meets one of the following two criteria: (1) crack initiation at the end of the 30 years design period or (2) an ‘endurance’ limit of 70 μS. The strain is computed for a single axle load of 130 kN, effective temperature corresponding to Israeli environmental conditions and local material properties. Typical sections of the perpetual pavement for 30 years design life period are composed of 300 mm HMA layers. Granular subbase thickness ranges between 150 and 650 mm for subgrade CBR of 10 and 3%, respectively. The results are evaluated with respect to the design guidelines of Illinois, Michigan catalogue and the UK diagram.

Keywords:

• perpetual pavement
• long lasting asphalt pavement
• fatigue cracking
• rutting
• rich base asphalt layer
• SMA

Acknowledgements

The research work was sponsored by ‘Israel National Roads Company’. The authors wish to thank the Research and Development Department staff for their cooperation and technical assistance.