Abstract
The conversion of ballasted railway tracks into slab tracks using the preplaced aggregate concrete (PAC) technology over the bridges and in the tunnels has been introduced by many researchers but the flexural behavior of this composite system has not yet been studied. Therefore, in the first stage, a series of mortar and concrete mixture designs were proposed and evaluated. Subsequently, a concrete beam mold with dimensions of 3 * 0.6 * 0.5 m, which represented the track conditions, was developed and the bending behavior of the constructed beams in both conditions of the presence and absence of the concert B70 sleeper were investigated. The maximum bending force in the middle of the concrete beam without a sleeper (SE) equaled 177.5 kN. In addition, the average values of bending tolerance by the sleeper including a PAC beam for three specimens in the four modes of the positive moment of midspan (SPM), negative moment of midspan (SNM), positive moment of rail seat (SPR), and negative moment of rail seat (SNR) were 55.25 kN m, 32.5 kN m, 91.84 kN m, and 38.21 kN m, respectively, which met the requirements of the AREMA regulations.
Highlights
The railway track system generally consists of rails, fasteners, sleepers, a ballast, a sub-ballast, and a subgrade
A force of 151.02 kN was first applied until the preplaced aggregate concrete (PAC) failed (Fig. 16) at the deflection of 0.51 mm, which was less than the maximum bending force tolerated by pure concrete beams
The maximum positive value generated at the sleeper support obtained by this equation is equal to 15.97 kN, which is much less than the positive moment tolerated by PAC beams
Summary
The railway track system generally consists of rails, fasteners, sleepers, a ballast, a sub-ballast, and a subgrade. In ballasted tracks, the initial stage of this method, which is the placement of aggregates, has been previously performed, so the entire system can be converted into slab tracks via the injection of mortar This new technology has been employed in countries such as South Korea and Japan. The void imprisoned between the aggregates is filled using mortar to adhere to the aggregates and transmit the imposed force This causes the PAC to perform well in compression and tension condition and, subsequently, the PAC slab will not require bending reinforcement, because PAC has a specific stress distribution mechanism at which the stresses are transferred through contact areas between aggregate particles. 2.1.3 Water Ordinary tap water with a pH of 7 and a maximum temperature of 23 °C was utilized in accordance with ASTM D1193 (2011)
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