This paper describes some important aspects of the repeated load triaxial testing at the CSR Readymix Laboratories in NSW and discusses the modifications of the MATTA machine and the results of calibration tests performed on a polyurethane specimen. Among the modifications, the use of a permanent magnet for connecting the piston to the top platen is important to avoid sample disturbance. Lubricated platens have been employed to produce reasonably uniform distribution of stress and strain in the sample. On-specimen deformation measurement technique has been developed to incorporate embedded targets. The use of a split mould with vacuum enables preparation of specimens of dry cohesionless materials. of dry cohesionless materials. Some typical results obtained from a series of tests on a sandstone material are described. It is also found that the Australian Standard has recommended the application of very high stress levels which may fail the specimen prematurely. (A)
Abstract