A new degradation model for life cycle assessment of railway ballast materials

This study presents a correlation between two specific aspects of railway ballast experiments for better understanding and assessment of materials degradation. Firstly, standard tests for quality control of ballast aggregates and related degradation indices/methods have been investigated and accordingly, an Improved Ballast Quality Index (IBQI) has been developed. Secondly, a series of ballast box test has been performed to identify the aggregates long-term behavior such as settlement, fouling condition, and particles breakage. Box tests have been done at three stages of 100,000, 300,000, and 500,000 load cycles. At each stage, by performing durability tests and calculating the developed index, the quality of ballast materials has been determined in parallel. Analysis of the results shows that IBQI can predict the long-term behavior of ballast with high levels of compatibility (less than 10% average difference between the results in a conservative manner). Hence, it can be used as a simple and practical method for estimation of ballast degradation and its life cycle prediction. Finally, a life cycle degradation model has been proposed to demonstrate the capability and applicability of IBQI. (C) 2020 Elsevier Ltd. All rights reserved.