Effects of Redispersible Polymer Powder on Mechanical and Durability Properties of Preplaced Aggregate Concrete with Recycled Railway Ballast

Sahyeon Lee,Eun Jong Ahn,Seung Yup Jang,Myoungsu Shin,Seongwoo Gwon,Seung Pil Kim,Chan Young Kim

doi:10.1186/s40069-018-0304-1

Abstract

The rapid-hardening method employing the injection of calcium sulfoaluminate (CSA) cement mortar into voids between preplaced ballast aggregates has recently emerged as a promising approach for the renovation of existing ballasted railway tracks to concrete tracks. This method typically involves the use of a redispersible polymer powder to enhance the durability of the resulting recycled aggregate concrete. However, the effects of the amount of polymer on the mechanical and durability properties of recycled ballast aggregate concrete were not clearly understood. In addition, the effects of the cleanness condition of ballast aggregates were never examined. This study aimed at investigating these two aspects through compression and flexure tests, shrinkage tests, freezing–thawing resistance tests, and optical microscopy. The results revealed that an increase in the amount of polymer generally decreased the compressive strength at the curing age of 28 days. However, the use of a higher polymer ratio enhanced the modulus of rupture, freezing–thawing resistance, and shrinkage resistance, likely because it improved the microstructure of the interfacial transition zones between recycled ballast aggregates and injected mortar. In addition, a higher cleanness level of ballast aggregates generally improved the mechanical and durability qualities of concrete.

Highlights

In modern times, the enhancement of the traveling speed and capacity of trains have been among the main issues facing public transportation systems around the world
These needs have been met by the continuous advancement of the classical railway track system, which consists of ballasted tracks, along with the development of train technologies (Bezin et al 2010)
The compression tests were conducted at 28 days of curing, as well as at the early hours of curing noted in Table 5, 3.2 Flexure Test The effects of the test variables on the tensile capacity of preplaced aggregate concrete (PAC) with recycled ballast aggregates were investigated by modulus-of-rupture tests in accordance with ASTM C78 (2016)

Summary

Introduction

The enhancement of the traveling speed and capacity of trains have been among the main issues facing public transportation systems around the world. These needs have been met by the continuous advancement of the classical railway track system, which consists of ballasted tracks, along with the development of train technologies (Bezin et al 2010). The percentage of slab tracks for Japanese high-speed lines has greatly increased since the introduction of the Sanyo Shinkansen line in 1972 (Miura et al 1998; Paixão et al 2009). The use of slab tracks has risen in many European countries (Paixão et al 2009)

Objectives

Methods

Results

Conclusion