ABSTRACT
Aggregates are a necessary and important resource for the construction of pavements worldwide. In order to reduce the risk of early pavement failure, it is required to use aggregates with high resistance against plastic deformation in both - wet and dry conditions, especially for high trafficked pavements.
The use of high quality UGMs significantly improve the rutting performance of the base course and hence, that of the whole pavement. Repeated Load Triaxial (RLT) tests results could give detailed information as to which UGMs should be selected in order to provide sufficient performance. However, these RLT tests are expensive and time consuming. In addition, this testing are quite complicated and only a few testing devises are available in Germany. Therefore, there is a need of simple and economical test methods to characterize the mechanical behaviour of UGMs under the action of high traffic loads. The paper shows the principle of operation and methodology of a simplified test (Repeated Load CBR (RLCBR) test) used to characterize the elastic and plastic response of UGMs to harmonic loads using a uniaxial testing machine. Different UGMs commonly used in the base course of Federal roads in Germany were tested at two different moisture contents. The results of the tests were analysed regarding the elastic deformation response showed a strong dependency of bearing capacity on the stress level. The RLCBR tests results were compared to the RLT test results and it was found that it is possible to determine the parameter of a non-linear elastic model for UGMs (Modified Universal Model) with a relatively high accuracy. The testing regime used and test results are discussed in this paper.
