The use of repeated load triaxial test (RLTT) for determining resilient modulus and permanent strain of unbound materials has been increasing in Australia. Austroads have recently developed standard specifications for test equipment and testing procedures for RLTT and industry has also developed low cost equipment and software which meet the required standards. Recently, inter-laboratory precision studies of resilient modulus and permanent strain testing on proving rings and actual crushed rock samples have been carried out to validate the test method and check the equipment and software. The precision studies identified several problems involved with the equipment and software specifications, sample preparation methods and interpretation of test results. As a result of this investigation, new modifications of current standard equipment/software and test procedures are introduced to produce more reliable RLTT results. This would enable development of performance characterisation indices, and performance-based specifications for unbound materials based on RLTT results. It would also enable practitioners to confidently apply the tests in a range of applications, from the ranking of materials to pavement design. (A)
Samenvatting