Numerical and Experimental Study of the Unsaturated Hydraulic Behavior of a Railroad Track Profile Considering Fouled Ballast Subjected to Tropical Climate Condition

Evaluating Different Track Sub-Ballast Solutions Considering Traffic Loads and Sustainability

“…The mixture potential is also attributed to the presence of stable minerals such as hematite, kaolinite, and goethite, which are relevant to sub-ballast layer applications, as reported by Castro et al [20] and Guimarães et al [38]. Additionally, the coarse grains contribute to a higher stability and stiffness and better interlocking within the material.…”

“…Different materials can be employed as sub-ballasts, such as well-graded crushed rock [2,35], hot mix asphalt underlayment [36,37], and lateritic tropical soils from quarries [20,38]. Regarding the latter, Castro et al [20] and Guimarães et al [38] explain that these types of soils contribute to better railway track behaviour as sub-ballasts because their clay fraction contains minerals from the kaolinite group and hydrated iron and aluminium oxides, which are considered stable in the presence of water and can bind their particles.…”

“…Different materials can be employed as sub-ballasts, such as well-graded crushed rock [2,35], hot mix asphalt underlayment [36,37], and lateritic tropical soils from quarries [20,38]. Regarding the latter, Castro et al [20] and Guimarães et al [38] explain that these types of soils contribute to better railway track behaviour as sub-ballasts because their clay fraction contains minerals from the kaolinite group and hydrated iron and aluminium oxides, which are considered stable in the presence of water and can bind their particles. Studies on stabilising local soils with recycled ballast fouled with iron ore or binder, such as cement, to improve their strength and deformability characteristics are still scarce, so further exploration may be interesting from an environmental and economical point of view.…”

“…Some railways have employed the RMFRM in their rehabilitation processes, as reported by Schilder and Piereder [21], Auer et al [22], Mundrey [23], and Fu et al [42]. According to Schilder and Piereder [20] and Auer et al [21], the RMFRM can save up to 50% of the amount of new material required. However, the excavated materials should meet the specifications, as previously mentioned.…”

“…Ebrahimi and Keene [5] advocate for the cost-effective and sustainable practice of reusing materials obtained from ballast cleaning to construct a new sub-ballast layer, as opposed to disposal, which incurs additional expenses. The inclusion of iron ore as a fouling material may enhance the hydro-mechanical behaviour by improving interparticle contact, filling voids, and increasing stiffness, as observed in [19,20].…”