BALANCING DAMPING GAINS AND STRENGTH LOSSES IN RUBBER-MODIFIED CEMENT ASPHALT MORTAR

Abstract

Cement asphalt mortar (CAM) serves as a damping layer on non-ballasted tracks. The development of the damping characteristics of the CAM suggests using rubber powder as a substitute for fine aggregate to improve the damping properties. Rubber powder problems stem from potential significant decreases in mechanical properties. Meanwhile, the rubber content must be limited to achieve optimal mechanical and dumping properties. This study aims to systematically investigate the mechanical and damping characteristics of rubber powder-modified CAM to balance damping gains and strength losses. Mechanical properties are determined by compressive strength characteristics. Damping properties are determined by the damping ratio. Results showed that the rubber powder-modified CAM at 0%, 10%, 15%, and 20% exhibited that at 10% slightly decreased the compressive strength of CAM compared to 0%, while 15% and 20% significantly decreased it. The rubber powder-modified CAM at 10% exhibits better performance in terms of increasing the damping ratio, which has a relatively slight influence on the compressive strength loss of CAM. The rubber powder-modified CAM at 10% with a low asphalt content of 0.2 shows an increase in ductility, whereas at a high asphalt content of 0.6, it decreases compared to the rubber powder-modified CAM at 0%. The elastic modulus and dynamic modulus decrease with the rubber powder-modified CAM and significantly decrease with increasing asphalt content. The damping properties increased with the rubber powder-modified CAM and rose considerably with increasing asphalt content. The natural frequency decreases with the rubber powder-modified CAM and significantly decreases with increasing asphalt content.