Application of Preplaced Aggregate Concrete to Convert the Ballasted Railway Tracks into Slab Tracks
Journal Title: Trends in Civil Engineering and its Architecture - Year 2018, Vol 1, Issue 5
Abstract
One of the most critical restrictions of ballasted railway tracks maintenance is the ballast undercutting and sieving over the railway bridges and tunnels. In recent years with respect to the development of in-place concrete slab track construction, using preplaced aggregate concrete technology is known as a new method to convert the ballasted railway tracks into slab track. Since no detail has been published regarding to design and construction of such systems by various railway owners, so the present study is allocated to this issue. In this matter, firstly some accomplished projects using this system has been reviewed and secondly, the detail evaluation of preplaced ballast concrete performance has been investigated in lab environment. In this former stage, by using the developed laboratory-scaled facilities, many cylindrical specimens have been constructed and tested. Consequently, their flow time and related compressive and splitting tensile strengths have been presented and the optimum injected mortar mix design have been reported. Preplaced Aggregate Concrete (PAC) is referred to a kind of concrete making by first placing coarse aggregate in the formwork and then injecting a sand-cement mortar to fill the voids imprisoned between the coarse aggregate particles. In order to operate safely, it is highly essential to maintain railway tracks over specific periods of time so that any detected defects in track components become obviated [1]. Generally, maintenance activities in ballasted railway tracks is more important in comparison with ballast less ones, because the former is tend to geometrical defects like asymmetric settlement and twist due to flexible behavior of ballast under three- directional loads [2]. On the other hand, ballast fauling can reduce track vertical and transverse strength in wet weather condition by decreasing its resilency. This cause's track instability and vehicle derailment. Also, rise of passing traffic in busy lines can limit the total repair time, which brings track closure and passenger dissatisfaction [3]. All these factors privilege ballast less (slab) tracks to ballasted ones and propel engineers to use Preplaced Aggregate Concrete (PAC) technology so that the total life cycle cost and maintenance activity of railway tracks decrease over their lifetime. In 1937, PAC was utilized to repair a tunnel in California. This kind of concrete was being consumed for repairing tunnel structures for many years. Then, USBR (United States Bureau of Reclamation) used this method to rebuild a part of Hoover dam. In 1946, this method was used to repair Barker dam in Colorado in which the mortar injection was finished after 10 days. US Army Corps of Engineers utilized this method to construct 34 bridge columns with 380000 cubic meters of concrete in 1951. From 1950 on, this method is commonly used in Japan, Australia and many other countries [4].
Authors and Affiliations
Morteza Esmaeili, Milad Hosein Esfahani, Ali Hemati
Keywords
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- EP ID EP606831
- DOI 10.32474/TCEIA.2018.01.000121
- Views 82
- Downloads 0
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