The effect of using rest periods in 4PB tests on the fatigue life of grouted macadams

Four-point bending tests are commonly used to assess the fatigue resistance of bi-tuminous bound materials that are used in road pavements. However, it is difficult to establish a reliable relationship between the laboratory test results and the field performance of the mate-rial. In order to predict the real life of the pavement, shift factors are normally used to convert the fatigue results obtained in the laboratory onto the actual fatigue life of the material in the field. Those shift factors depend on the type of test used, the testing conditions and the type of mixture used. In this study, an attempt was made to establish a shift factor for grouted mac-adams, based on four-point bending fatigue test results carried out with rest periods between the loading cycles. The result obtained was used to define a fatigue criterion for pavement design with grouted macadams