A study on enhancement of the static/dynamic property of polymer concrete for the reduction of rolling noise in railway

Abstract

Concrete cement has been widely used in civil engineering structures owing to its flexibility and high load-holding capabilities. However, Portland cement concretes have exhibited problems resulting from excessive noise and vibration generation due to their low damping. Polymer concretes made of epoxy resins were studied, and their ability to reduce noise/vibration in concrete slab tracks was examined. The polymer concretes were fabricated using different mixing ratios between epoxy resins and aggregates of different sizes. The effects of these parameters on the compressive and flexural strengths of the obtained polymer concretes were measured to study their mechanical reliability in water environments. In addition, frequency-dependent variations of stiffness and damping in the polymer concretes were obtained by impact vibration tests conducted to investigate their ability to reduce vibrations. In-situ cure monitoring was also performed for the polymer concretes by measuring the dissipation factor of epoxy resins to determine the proper curing cycle necessary to reach the fully cured state. Using 20 wt.% of the epoxy resin and a 1:2 mixing ratio of fine aggregate to coarse aggregate in the polymer concrete synthesis, we were able to reduce noise and vibration and maintain a compressive strength comparable to that of cement concrete. The produced polymer concrete was reinforced with carbon fibers to enhance its mechanical and dynamic properties. The fiber surface was characterized using X-ray photoelectron spectroscopy (XPS) analysis and scanning electron microscopy (SEM). The flexural strength of the polymer concrete was measured using a 3-point bending test. In addition, frequency-dependent variations in the stiffness and loss factor for the reinforced polymer concrete were obtained by conducting impact tests. The fatigue characteristics of the polymer concrete and carbon fiber-reinforced polymer concrete were evaluated by performing fatigue tests under cyclic loading. The carbon fiber-reinforced polymer concrete having 12 mm of the fiber length and 2 wt.% of the fiber content showed a flexural strength of 25.12 MPa and a damping value of 0.01954 indicating higher durability than that of the polymer concrete. To examine the applicability of the produced polymer concrete to actual railways, a 1/6 scale model of a railway structure was fabricated. As the result, the carbon fiber-reinforced polymer concrete reduced 7 dB of the noise level obtained for a polymer concrete sleeper. In actual applications, the polymer concrete can reduce maintenance costs of railways owing to its high durability as compared with that of conventional cement concrete.