Determination and evaluation of railway aggregate sub-ballast gradation and other properties variation

Abstract

The use of high quality aggregate mixture, proper technological parameters of laying and compacting as well as the required thickness of the mixture ensures railway sub-ballast layer properties. In this paper gradation, density and water permeability of 49 produced random samples of aggregate sub-ballast (ASB) mixture which were taken from the stockpile in the plant and from the uncompacted railway layer are investigated. The statistical parameters of the ASB mixture quality indicators and histograms with theoretical curves of normal distribution are presented as well. Their conformity to normal distribution was tested through the use of skewness, kurtosis, Pearson, Shapiro-Wilk and Kolmogorov-Smirnov methods. Regression analysis was employed to determine the dependence of standard deviation of percent passing on the mean percent passing through the sieves. In this paper a new method of determining the homogeneity of ASB according to the variation of gradation using the maximum standard deviation value of this dependence was employed. The minimum size n was calculated with the permissible relative error of 5%, 10%, 15% and 20%. The obtained research findings revealed that due to segregation processes the homogeneity of ASB mixture from the point of its production to application has decreased by about 38%.

Keywords:

• railway track
• aggregate sub-ballast (ASB)
• gradation
• water permeability
• mixture density
• stockpile
• layer
• homogeneity
• normal distribution
• sample size

Additional information

Notes on contributors

Deividas Navikas

Deividas NAVIKAS. PhD student at the Department of Transport Technological Equipment of Vilnius Gediminas Technical University. He received his Master‘s degree in 2012 at Vilnius Gediminas Technical University. Research intrests: railway infrastructure elements, it‘s modelling and evaluation.

Matas Bulevičius

Matas BULEVIČIUS. Defend doctoral dissertation in 2014 at Vilnius Gediminas Technical University. He received his master degree in 2005 at Vilnius Gediminas Technical University. He is also the author and co-author of 3 publications as well as 8 research and technical reports. Currently is a director of JSC “Granitinė skalda”. He is a chairman of technical committee of road building materials and member of technical committee of geotechnical engineering of Lithuanian standards board. His research interests include mechanical-physical properties of aggregates, used for producing asphalt mixtures, bituminous binders, road pavement constructions.

Henrikas Sivilevičius

Henrikas SIVILEVIČIUS. Professor Dr Habil at Vilnius Gediminas Technical University. Education: Road construction engineering, VISI (VGTU), 1972, Candidate of technical sciences Moskow (MADI), 1984; Associate professor, VGTU, 1990; Doctor of technical sciences, VGTU, 1993; Doctor habilitaties, VGTU, 2003; Professor, VGTU, 2005. Publications: more than 200 scientific papers. Research intrests: flexible pavement life cycle, hot mix asphalt mixture production technology, application of statistical and quality control methods, recycling asphalt pavement technologies and design, decision-making and expert systems theory and applications, improvement railway passengers trip and infrastructure quality.