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Effect of moisture on the engineering characteristics of fouled ballast

TitleEffect of moisture on the engineering characteristics of fouled ballast
Publication TypeConference Paper
Year of Publication2014
AuthorsHo CL, Light T, Lambert RS
Conference NameTransportation Research Board 93rd Annual Meeting
Date Published01/2014
PublisherTransportation Research Board
Conference LocationWashington, D.C.
Accession Number01518790
KeywordsGeotechnology; Materials; Railroads; I35: Miscellaneous Materials; I40: Soils and Rocks

Crushed rock, or ballast, provides the foundation for nearly all of the rail networks worldwide. Given the widespread use of ballast, understanding the impacts of its degradation with time is essential to maintaining the desired performance of railways. Over time, ballast fouling occurs through natural transport processes (wind and precipitation) and the crushing of the ballast particles. As fouling becomes more severe, it has the capacity to become a major maintenance issue for the track bed. To quantify the impacts of fouling materials on the engineering parameters of both dry and wet ballast, large ballast samples were tested. Consolidated, drained triaxial tests were completed on ballast samples containing 0%, 10%, and 20% fouling particles (passing the #10 sieve) respectively. The tests were conducted to provide axial load and axial and circumferential displacement data for wet ballast at confining stresses ranging from 5 to 15 psi (35 to 100 kPa). Upon completion of the laboratory work, data analysis provided shear strength, stress-strain, volumetric strain, Poisson’s ratio, and Young’s modulus for each sample tested. A comparison between the wet and dry experiments was conducted which allowed the assessment of the impact of water on rail ballast to be clearly identified. Wet ballast was observed to fail at a lower axial stress difference and exhibit a lower ultimate stress difference than dry ballast. Wetted ballast samples were also found to have a significantly lower initial tangent modulus than dry ballast but exhibited similar Mohr-Coulomb parameters at failure.