Jordan Journal of Civil Engineering, Volume 13, No. 4, 2019 - 594 - © 2019 JUST. All Rights Reserved. The Role of Scrap Rubber, Asphalt and Manual Compaction against the Quality of Ballast Layer Dian M. Setiawan 1) , Sri Atmaja P. Rosyidi 2) and Cahyo Budiyantoro 3) 1) Lecturer, Universitas Muhammadiyah Yogyakarta, Indonesia. E-Mail: diansetiawanm@ft.umy.ac.id 2) Doctor, Universitas Muhammadiyah Yogyakarta, Indonesia. E-Mail: atmaja_sri@umy.ac.id 3) Universitas Muhammadiyah Yogyakarta, Indonesia. E-Mail: mesin@umy.ac.id ABSTRACT This research utilizes scrap rubber from outer motorcycle tires and asphalt of 60/70 penetration as a ballast layer mixture component. The objective of this study is to evaluate the characteristics of modified ballast with scrap rubber and asphalt mixtures and with two different numbers of manual compaction through a compressive strength test by analyzing elastic modulus, ballast material durability and vertical deformation. The most prominent finding to emerge from this study is that the more compaction times and the presence of asphalt, the higher the elastic modulus, the lower the ballast material abrasion and the lower the vertical deformation; hence, the stiffer the ballast layer and the higher the ballast durability. Furthermore, the percentage of ballast material abrasion shows a decrease along with the use of scrap rubber and asphalt. However, in the ballast layer with scrap rubber, the presence of 10% of 3/8” scrap rubber will reduce the ballast layer stiffness. Lastly, in the ballast layer with scrap rubber, the compaction works were unable to impact optimally the vertical deformation reduction, since the ballast materials in the sample with scrap rubber tend to bounce off each other, so that the sample does not have sufficient and proper density and stiffness. KEYWORDS: 60/70 penetration asphalt, Ballast abrasion, Elastic modulus, Manual compaction, Scrap rubber, Vertical deformation. INTRODUCTION Ballast is one of the important components on the railroad to provide a stable and uniform foundation and to reduce the impact of loading to an acceptable level by subgrade (D'Angelo et al., 2016). At present, several studies have been carried out with the aim of reducing the impact of damage to the ballast layer, so that the cost of railroad maintenance can be decreased. The development of conventional railways the quality of which is close to the quality possessed by the slab track railroad is also an essential issue in railroad industry (Setiawan et al., 2013). The addition of other materials to the ballast layer is one method that can improve the quality of the ballast structure. Woodward et al. (2012) through their research have applied a unique material called in-situ polyurethane polymer to enhance the stability of ballast layers. However, the use of this material needs to consider its availability in railway industry. On the other hand, the use of used rubber material (Asgharzadeh et al., 2018; Sol-Sanchez et al., 2014; Sol-Sanchez et al., 2015; Signes et al., 2016) and asphalt (Mino et al., 2012; D'Andrea et al., 2012; Lee et al., 2014; D'Angelo et al., 2017; Bressi et al., 2018) can be an alternative to the use of other materials on railroad structures, especially ballast layers. Received on 9/8/2019. Accepted for Publication on 16/10/2019.