No abstract

Innovations in the field of railroad construction need to be improved, especially in the ballast layer which is an essential structure in conventional railways. The purpose of this study was to analyse the characteristics of vertical deformation and ballast material abrasion with 10% of scrap rubber in two types of sizes (uniform and graded) and with 3% of asphalt. This study uses a compressive test method with six types of samples modeled with ballast boxes measuring 400 x 300 x 200 mm. The test results present that the use of 10% scrap rubber can increase the vertical deformation value significantly to 84%. On the other hand, the use of 3% asphalt can minimize vertical deformation to only 14% because asphalt can increase the ballast layer stiffness. Furthermore, it can also be concluded that in general, the use of 10% scrap rubber and 3% asphalt can reduce the percentage of material abrasion up to 80%. Besides, it also can be known that the use of graded sized scrap rubber material is the most effective in increasing material durability. Scrap rubber and asphalt have the potential to be used together on ballast layers which are expected to be a solution of the problems related to the service-life and ballast maintenance work.

This study investigated the structural response of granular and asphaltic overlayment of rail track considering the linear viscoelastic behavior of asphalt. The calculation of the tensile strains at the bottom of the asphalt layer, the compressive stresses at the top of the subgrade layer, and the service life of the granular and the asphaltic overlayment rail track were conducted using the KENTRACK software. Furthermore, the sensitivity analysis by changing different factors was studied in this paper. The results of this study indicate that the asphaltic overlayment rail track structure has a much longer predicted service life than the granular rail track. It was also shown that the sub-grade compressive stress is more sensitive to the change in subgrade modulus than the change in ballast-sub-ballast-asphalt layer thickness and the change in binder type, respectively. In addition, the asphalt tensile strain is more sensitive to the change in asphalt layer thickness than the change in subgrade modulus and the change in binder type, respectively. These findings also enhance our understanding that subgrade compressive stress and asphalt tensile strain in the asphaltic overlayment track are more sensitive to the change in asphalt layer thickness than the change in binder type.

This research utilizes scrap rubber from motorcycle tires as a ballast layer mixture component. A compression test method was used with three test samples: ballast (sample I), ballast with 10% uniform graded scrap rubber (sample II) and ballast with 10% continuous graded scrap rubber (sample III). This research aims to analyze the elastic modulus, durability and vertical deformation of the ballast layer. It can be concluded that the elastic modulus of sample I, II, and III was 14.28 MPa, 8.53 MPa, and 3.10 MPa, respectively. Moreover, the abrasion of sample I, II, and III was 162.1 gr (3.24%), 54.2 gr (1.08%), and 50.1 gr (1%). Furthermore, at the same number of vertical deformation (5 mm), the sample I was able to receive the most considerable load that is 1980.9 Kg, followed by sample II by 1252.2 Kg and sample III by 443.7 Kg.

To determine performance of rigid pavement, pavement engineers should not only conduct stress, curling, and deflection analysis, but also understand weather conditions and subgrade quality effects on rigid pavement performance well. This study aims to analyze and visualize the mechanical behaviors of rigid pavement in terms of stress, curling, and deflection using the KENPAVE Program under different curling temperature and subgrade quality. Besides, this study also evaluated temperature differential and k-value effects on the stress, curling, and deflection behavior of concrete pavement. The findings revealed that there is a linear correlation between stress and both k-value and curling temperature, with the latter having more significant impact in controlling stress than the former. However, even though curling is not affected by subgrade quality, it significantly depends on the temperature differential since a higher curling temperature produces higher curling behavior. Lastly, a higher temperature differential produces greater deflection, but a higher k-value produces smaller deflection. Nevertheless, deflection behavior has a more significant curve and the position of the highest deflection shifted towards the center of the slab as the curling temperature and subgrade quality increase.