A New Technique for Quality Assessment of Railway Ballast Materials

The influence of main quality tests on the overall quality of railway ballast materials is assessed in this study. The need to integrate all acceptance tests in a unified manner for precise evaluation of ballast quality is identified, and a technique of performing this is proposed. Using this approach, a new ballast quality index (BQI) is defined in which, the main acceptance tests including abrasive strength, abrasive hardness, fragmentation strength under external loads and weathering resistance, are considered. For the development of the new BQI, all tests results are combined, assigning justified coefficients to each test value according to its contribution on overall quality. Moreover, the comparison of the new index versus the Abrasion Number (AN) as a proposed approach of the Canadian Pacific Railroad for ballast selection is investigated. A practical use of the new index is finally presented with regard to the laboratory investigations on different ballast rocks, to indicate its capability and applicability.