The Effect of Degree of Fouling of Coal Dust on Railway Foundation Stability

  • F. N. OkontaEmail author
Conference paper
Part of the Sustainable Civil Infrastructures book series (SUCI)


Railway ballasts and large aggregates can be fouled internally by inter particle weathering and externally by soil pumping and deposition of rail fright particles. The gradual accumulation of soil fines and coal particles on road pavements, rail ballast and sleepers affect the aggregate interlocking properties. Track maintenance and ballast replacement schedule are dependent on the different classification methods used to evaluate the degree of fouling. Uniformly graded large aggregates were fouled with different percentages of residual fines of coal dusts that were prepared at different moisture content (w). The degree of fouling of the coal dust fouled aggregates (CDFA) were classified according to the percentage of fouling (PF) and Relative ballast fouling ratio (RBFR). The interlocking properties of the fouled aggregates were investigated in a large direct shear device and the Intergranular Friction Angles (IFA) were determined. Degree of fouling up to 8% had no effect on the dry density of the aggregate, between 8 and 16% the effect of fouling was marginal, however linear relationship was indicated beyond 16% fouling. The rate of decrease of IFA was found to be dependent on the degree of fouling and moisture content of the coal material. The IFA of the CDFA tend towards the IFA of the wet coal materials as the degree of fouling increase to 20% of the dry mass of the aggregate. 20% fouling represent moderately fouled and fouled conditions in accordance with PF and RBFR fouling classifications respectively. RBFR is based on the inter aggregate void volume occupied by the fouling material and specific gravity of coal. It was found to be more sensitive to the changes in IFA than PF. Regression models of the effect of coal dust fouling on aggregate integranular and interface friction based on IFA, MC, PF and RBFR were formulated and proposed for the development of track maintenance scheme, ballast replacement schedule and standard track inspection routines.


Angle of friction Gravels Direct shear strength Interface shear strength Fouling Railway ballasts Percentage of fouling (PF) and relative ballast fouling ratio (RBFR) Shear box apparatus Optimum moisture content Maximum dry unit weight Coal dust 



The field work and fabrication of shear box was funded by Rand Coal Engineering PLc. The author is grateful.


  1. Das, S.K., Yudhbir, S.: Geotechnical characterization of some Indian fly ashes. J. Mater. Civ. Eng. 17(5), 546–556 (2005)CrossRefGoogle Scholar
  2. Gentzis, T.: Geomechanical properties and permeability of coals from the Foothills and Mountain regions of Western Canada. Int. J. Coal Geol. 69(3), 153–164 (2007)CrossRefGoogle Scholar
  3. Indraratna, B., Salim, W.: Mechanics of ballasted rail tracks—a geotechnical perspective. Taylor and Francis, London (2005)Google Scholar
  4. Indraratna, B., Khabbaz, H., Salim, W.: Geotechnical properties of ballast and the role of geosynthetics in rail track stabilisation. Ground Improv. 10, 91–101 (2006)CrossRefGoogle Scholar
  5. Indraratna, B., Su, L., Rujikiatkamjorn, C.: A new parameter for classification and evaluation of railway ballast fouling. Can. Geotech. J. 48, 322–326 (2011)CrossRefGoogle Scholar
  6. Janardhanam, R., Desai, C.S.: Three-dimensional testing and modeling of ballast. J. Geotech. Eng. 109(6), 783–796 (1983). Scholar
  7. Jasinge, D.: Mechanical properties of reconstituted Australian black coal. J. Geotech. Geoenviron. Eng. 135(7), 980–985 (2009)CrossRefGoogle Scholar
  8. Karim, A., Salgado, R., Lovell, C.W.: Building embankments of coal combustion fly ash-bottom ash mixtures. In: Proceedings of 48th Highway Geology Symposium, pp. 66–74. Knoxville, TN, May 1997Google Scholar
  9. Kim, B., Prezzi, M., Salgado, R.: Geotechnical properties of fly and bottom ash mixtures for use in highway embankments. J. Geotech. Geoenviron. Eng. 131(7), 914–924 (2005)CrossRefGoogle Scholar
  10. Kim, B.J., Yoon, S.M., Balunaini, U.: Determination of ash mixture properties and construction of test embankment—part a. Joint Transportation Research Program, Final Report, FHWA/IN/JTRP-2006/24! Purdue University, W. Lafayette, Indiana, pp 345–352 (2006)Google Scholar
  11. Marto, A., Mahir, A.M., Lee, F.W., Yap, S.L., Muhardi. K.: Morphology, mineralogy and physical characteristics of Tanjung Bin coal ash. In: Proceedings of 4th International Conference on The Recent Advanced in Materials, Minerals and Environment (RAMM) and 2nd Asian Symposium on Material & Processing (ASMP), 1–3 June 2009, Pulau Penang, Malaysia, pp. 34–42 (2009)Google Scholar
  12. Pen, L.W., Powrie, A., Zervos, S., Ahmed, S., Aingaran, S.: Dependence of shape on particle size for a crushed rock railway ballast. Granular Matter 15(6), 849–961 (2013)CrossRefGoogle Scholar
  13. Rottcha, C.: Geotechnical properties of discarded coal from rail sidings. BIng Thesis, (Unpublished) University of Johannesburg, Civil Engineering Department (2011)Google Scholar
  14. Selig, E.T., Waters, J.M.: Track geotechnology and substructure management. Thomas Telford Services Ltd., London (1994)CrossRefGoogle Scholar
  15. Sevi, A., Ge, L.: Cyclic behaviors of railroad ballast with the parallel gradation scaling framework. J. Mater. Civil. Eng. 24(7), 797–804 (2012)CrossRefGoogle Scholar
  16. Thys, J.: Mining and population indices in South Africa. Report on Jobs in Provincial Sectors. MP GV Gazzette 0012. Public Works (2003)Google Scholar
  17. TMH: Standard methods of testing road construction material. In: Technical Methods for Highways, vol. 1. Pretoria, South Africa (1996)Google Scholar
  18. TRH 4: Department of Transport. Structural Design of Flexible Pavements for Interurban and Rural Roads. Technical Recommendation for Highways, pp. 1–101, Pretoria, South Africa (1994)Google Scholar
  19. Tutumluer, E., Bombrow, W., Huang, H.: Effect of coal dusts on railroad strength and stability. University of Illinois Lectures. In: 8th International Conference on the Bearing Capacity of Roads Railways and Airfields. June 29–July 2, Champaign Illinois USA (2009)Google Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Civil Engineering ScienceUniversity of JohannesburgJohannesburgSouth Africa

Personalised recommendations