Flexural Fatigue Performance of Ballastless Track Manufactured Sand Concrete: The Influence of Manufactured Sand Lithology and Stone Powder Content

Abstract

To address the limitations associated with the application of manufactured sand concrete (MSC) in railway ballastless track concretes, a fatigue test system conforming to actual service of ballastless track was developed to study the fatigue performance of MSC, including fatigue life, stiffness, and deformation, was systematically studied. The MSCs used for ballastless track were prepared with different typical lithologies including granite, basalt, limestone and tuff, and various stone powder contents(5%、10%、15%). The results showed that lithology of manufactured sand has a significant impact on MSC’s the fatigue performance, among which basalt sand concrete’s (BSC) fatigue life increased by 51.5% compared to river sand concrete (RSC). The rough surface and sharp edges of manufactured sand contribute to improved microhardness in the interface transition zone (ITZ) and subsequently enhanced mechanical and fatigue properties. The appropriate content of stone powder in MSC preserves its fatigue performance; however, an increased content of stone powder may lead to a degradation of the MSC's fatigue resistance. Taking tuff MSC as the research object, MSC with 5% stone powder content exhibited comparable fatigue performance compared to RSC. However, the fatigue life of concrete has reduced by 26.2% when stone powder content reaches 15%, because excessive stone powder content may cause defects at ITZ, which ultimately affect fatigue performance.

Keywords: manufactured sand concrete, ballastless track, flexural fatigue, lithology, stone powder content