Assessment of the Use of Polypropylene Fiber Reinforced Foam Concrete as a Subgrade Material for the China Railway Track System (CRTS) III Slab Ballastless Tracks

2021 ◽  
pp. 036119812110190
Author(s):  
Thanut Klomranok ◽  
Qian Su
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Polypropylene Fiber ◽  
Dynamic Strength ◽  
Railway Track ◽  
Fiber Reinforced ◽  
Foam Concrete ◽  
Traditional Structure ◽  
Track System ◽  
Full Cross Section

This paper presents the application and the development of foam concrete (FC) to replace the traditionally used subgraded materials (typically compacted soil or granular earth rock) in high-speed railway by using cement to sand ratio of 2:1 with a target density of 500 to 700 kg/m3 and by adding polypropylene (PP) fibers with 0.25% and 0.40% by volume to improve the properties of FC. The mechanical properties were evaluated and tested in the laboratory in accordance with ASTM standard method, including compressive strength, tensile strength, modulus of elasticity and Poisson’s ratio, and dynamic strength. In addition, the numerical model investigates the performance and analyzes the effect of applying the full cross-section PP fiber reinforced FC in slab ballastless track, under different thicknesses, on the dynamic response of the whole structure, and then compares them with that of the traditional structure. The results indicate that the strength of FC with a density of 500 to 700 kg/m3 can meet the requirements of static and dynamic loading conditions of railway earth structure. But the density of 600 to 700 kg/m3 shows good strength stability under different curing states. In addition, adding 0.25% PP fiber is an optimal volume that can significantly improve mechanical properties. The prediction of the model shows that FC at a density of 600 kg/m3 by adding PP fibers of 0.25% at a thickness of 1.5 m can reduce the stress and vibration of the track structure better than that of the traditional structure; this indicates a long-term maintainance stability of the subgrade bed.

scholarly journals Laboratory Investigation of the Temperature-Dependent Mechanical Properties of a CRTS-Ⅱ Ballastless Track-Bridge Structural System in Summer

2020 ◽  
Vol 10 (16) ◽  
pp. 5504
Author(s):  
Lingyu Zhou ◽  
Yahui Yuan ◽  
Lei Zhao ◽  
Akim Djibril Gildas Mahunon ◽  
Lifan Zou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Relative Displacement ◽  
Railway Track ◽  
Structural System ◽  
Depth Direction ◽  
Ballastless Track ◽  
Track System ◽  
Track Bridge ◽  
Structural Strain

To study the mechanical properties of the China Railway Track System type II (CRTS-II) ballastless slab track structure, a 1/4-scale specimen of a CRTS-II slab ballastless track-32-m standard prefabricated simply supported box girder bridge with three spans and two high-speed railway lines was developed. The mechanical properties of the structure under the action of daily natural temperatures were studied under the natural environmental conditions. The structural strain and relative interlayer displacements were analyzed. The results show that the temperature of the CRTS-II ballastless track-bridge structural system changes periodically every 24 h. The strain of the structural layers of the track system first increases and then decreases sinusoidally, and the internal strain of the track system lags along the vertical depth direction. The relative displacement between the layers of the ballastless track bridge structure system increases with the increase in temperature. The extreme value of the vertical relative displacement appears between the track bed and the bridge at section 1/4 in the span, so it should be paid attention to by the maintenance personnel. Due to the constraint of the shear slots, the structural strain and relative displacement at the fixed end near the shear slots are smaller than those at the sliding end. The mid-span deflection is the largest, and the overall deflection during the cooling phase is more significant than that during the heating phase.

scholarly journals Thermoplastic Reaction Injection Pultrusion for Continuous Glass Fiber-Reinforced Polyamide-6 Composites

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 463 ◽  
Author(s):  
Ke Chen ◽  
Mingyin Jia ◽  
Hua Sun ◽  
Ping Xue
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
High Speed ◽  
Flexural Modulus ◽  
Polyamide 6 ◽  
Thermoplastic Composites ◽  
Fiber Reinforced ◽  
Pultrusion Process ◽  
Glass Fiber Reinforced ◽  
Pultruded Composites

In this paper, glass fiber-reinforced polyamide-6 (PA-6) composites with up to 70 wt% fiber contents were successfully manufactured using a pultrusion process, utilizing the anionic polymerization of caprolactam (a monomer of PA-6). A novel thermoplastic reaction injection pultrusion test line was developed with a specifically designed injection chamber to achieve complete impregnation of fiber bundles and high speed pultrusion. Process parameters like temperature of injection chamber, temperature of pultrusion die, and pultrusion speed were studied and optimized. The effects of die temperature on the crystallinity, melting point, and mechanical properties of the pultruded composites were also evaluated. The pultruded composites exhibited the highest flexural strength and flexural modulus, reaching 1061 MPa and 38,384 MPa, respectively. Then, effects of fiber contents on the density, heat distortion temperature, and mechanical properties of the composites were analyzed. The scanning electron microscope analysis showed the great interfacial adhesion between fibers and matrix at 180 °C, which greatly improved the mechanical properties of the composites. The thermoplastic reaction injection pultrusion in this paper provided an alternative for the preparation of thermoplastic composites with high fiber content.

Mechanical Properties of Polypropylene Fiber Concrete after High Temperature

2014 ◽  
Vol 662 ◽  
pp. 24-28 ◽  
Author(s):  
Xi Du ◽  
You Liang Chen ◽  
Yu Chen Li ◽  
Da Xiang Nie ◽  
Ji Huang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Polypropylene Fiber ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Fiber Concrete ◽  
Compressive Strength Of Concrete ◽  
Polypropylene Fiber Reinforced Concrete

With cooling tests on polypropylene fiber reinforced concrete and plain concrete that were initially subjected to different heating temperatures, the change of mechanical properties including mass loss, uniaxial compressive strength and microstructure were analyzed. The results show that the compressive strength of concrete tend to decrease with an increase in temperature. After experiencing high temperatures, the internal fibers of the polypropylene fiber reinforced concrete melted and left a large number of voids in it, thereby deteriorating the mechanical properties of concrete.

Moving element analysis of discretely supported high-speed rail systems

2017 ◽  
Vol 232 (3) ◽  
pp. 783-797 ◽  
Author(s):  
Jian Dai ◽  
Kok Keng Ang ◽  
Minh Thi Tran ◽  
Van Hai Luong ◽  
Dongqi Jiang
Keyword(s):  
High Speed ◽  
Railway Track ◽  
High Speed Train ◽  
Element Analysis ◽  
High Speed Rail ◽  
Mass System ◽  
Rail System ◽  
Rail Systems ◽  
Track System ◽  
The Difference

In this paper, a computational scheme in conjunction with the moving element method has been proposed to investigate the dynamic response of a high-speed rail system in which the discrete sleepers on the subgrade support the railway track. The track foundation is modeled as a beam supported by uniformly spaced discrete spring-damper units. The high-speed train is modeled as a moving sprung-mass system that travels over the track. The effect of the stiffness of the discrete supports, train speed, and railhead roughness on the dynamic behavior of the train–track system has been investigated. As a comparison, the response of a continuously supported high-speed rail system that uses a foundation stiffness equivalent to that of a discretely supported track has been obtained. The difference in results between the “equivalent” continuously supported and the discretely supported high-speed rails has been compared and discussed. In general, the study found that a high-speed train that travels over a discretely supported track produces more severe vibrations than that travels over a continuously supported track of equivalent foundation stiffness.

scholarly journals Experimental Investigation on Mechanical Properties of Hybrid Fiber Reinforced Quaternary Cement Concrete

2015 ◽  
Vol 10 (4) ◽  
pp. 155892501501000
Author(s):  
Ramesh Kanagavel ◽  
K. Arunachalam
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Impact Resistance ◽  
Polypropylene Fiber ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Cement Concrete ◽  
Split Tensile Strength ◽  
Polypropylene Fiber Reinforced Concrete

Mechanical properties of quaternary blending cement concrete reinforced with hybrid fibers are evaluated in this experimental study. The steel fibers were added at volume fractions of 0.5%, 1%, and 1.5 % and polypropylene fibers were added at 0.25% and 0.5% by weight of cementitious materials in the concrete mix individually and in hybrid form to determine the compressive strength, split tensile strength, flexural strength and impact resistance for all the mixes. The experimental results revealed that fiber addition improves the mechanical properties and also the ductility and energy absorption of the concrete. The results also demonstrate that the hybrid steel – polypropylene fiber reinforced concrete performs better in compressive strength, split tensile strength, flexural strength and impact resistance than mono steel and mono polypropylene fiber reinforced concrete.

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