A series of drained triaxial monotonic and cyclic tests was carried out to study the influence of particle breakage on the behaviour of a crushable limestone. Special attention was paid to the analysis of grain breakage during the loading and unloading process and the movement of the critical state line caused by grain breakage in the e-log (p') diagram. Monotonic test results show typical features of the behaviour of crushable granular materials compared to non crushable materials. For cyclic tests, it was found that certain particles were crushed during the cyclic loading and quantities of grain breakage increased slowly with the augmentation of loops.