Indirect estimation of railway ballast strength by conducting point load test on rock cores and irregular-shaped particles

ABSTRACT: Ballast layer comprised of coarse-grained aggregate facilitates drainage of rainwater from the railway track and distributes the stresses transmitted by the sleepers to the underlying layers. Breakage of ballast aggregate is mainly influenced by the properties related to the parent rock type. To evaluate the quality of parent rock used for producing crushed ballast aggregate, the strength of rock is estimated by conducting uniaxial compressive strength (UCS) test. Also, the point load test (PLT) could be used to indirectly estimate the strength of parent rock. In the present study, the strength of ballast material is evaluated by conducting UCS test and PLT on rock cores as well as irregular-shaped ballast particles to investigate the effectiveness of PLT as a simple test for estimation of strength of ballast particles. For this purpose, PLT as well as UCS test is carried out on rock specimens obtained from different quarries. Obtained results show that strong linear relationships exist between the strength estimated from diametral PLT and UCS test conducted on rock cores with the strength determined from PLT conducted on irregular-shaped particles.