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%.

Evaluation of Gradation Variation of the Granite Aggregates Used in Asphalt Mixtures at Their Manufacturing Place

“…Therefore, the arithmetic mean, calculated for each sieve by each of those three methods, differs. Usually, gradation of aggregate or aggregate mixture is expressed in percent passing through the sieves (Navikas et al, 2016). Statistical indicators of percent passing of the granite aggregates through separate laboratory sieves, histograms and theoretical curves of normal distribution are presented in Figure 2 below.…”

Multiple Criteria Evaluation and the Inverse Hierarchy Model for Justifying the Choice of Rail Transport Mode

“…It has been found that a weak railway subgrade may cause instability of the railway track system [7]. The problem of modelling railway track substructure has also been considered [8,9]. Krakovskiy et al [10] and Xu et al [11] described the evaluation of the technical condition of the rails, while Povilaitienė et al [12] described the possibility of decreasing rail wearing on the railway curve.…”

Prediction of Lifespan of Railway Ballast Aggregate According to Mechanical Properties of It

“…The main reasons for ballast degradation are ballast fragmentation and wear. They destine settlement of a road and increase expenses for maintenance of track geometry (Navikas et al 2016;Tennakoon et al 2014). The indicator of particles resistance to fragmentation, the coefficient of Los Angeles Abrasion (LAA), is determined by applying Los Angeles Abrasion test under standard (LST EN 1097-2:2010).…”