COMPARISON OF FATIGUE CRITERIA FOR FLEXIBLE AND SEMI-RIGID PAVEMENTS

The paper presents comparison of fatigue criteria which are used in mechanistic methods of pavement design. The following criteria were considered: (a) for fatigue cracking of asphalt layers and structural rutting (subgrade strain): LCPC and SETRA (France), Nottingham University (United Kingdom), Road Research Centre in Belgium, Shell and The Asphalt Institute (USA) and (b) for fatigue cracking of bases treated with hydraulic binders: CSIR (South Africa), Road Research Centre in Belgium, University of Illinois (USA). The aim of the comparison was to select suitable fatigue criteria for the revision of the 20-year-old Polish catalogue of typical pavements which was required due to significant increase in traffic volume and in axle loads. In the paper the fatigue formulas for all the considered criteria were given and fatigue curves were compared. Pavement structures with different base courses were designed for a range of traffic volumes with regard to various fatigue criteria and Polish design considerations. The designed structures were compared with pavement structures included in the old Polish catalogue of typical pavements which performance can be evaluated as acceptable. On this basis the following criteria were selected as suitable for Polish conditions: (a) for fatigue cracking of asphalt layers and structural rutting (subgrade strain) - The Asphalt Institute (USA), and (b) for fatigue cracking of cement treated bases - CSIR (South Africa), Road Research Centre in Belgium, University of Illinois (USA). New typical pavements structures were designed according to the selected fatigue criteria.