scholarly journals A Review on Cement Asphalt Emulsion Mortar Composites, Structural Development, and Performances

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3422
Author(s):  
Hussaini Abdullahi Umar ◽  
Xiaohui Zeng ◽  
Xuli Lan ◽  
Huasheng Zhu ◽  
Yirui Li ◽  
...  
Keyword(s):  
High Speed ◽  
Partial Replacement ◽  
Future Research ◽  
Structural Development ◽  
Asphalt Emulsion ◽  
Performance Properties ◽  
And Performance ◽  
Areas Of Interest ◽  
Emulsified Asphalt ◽  
Ca Mortar

The use of cement emulsified asphalt mortar (CA mortar) in the track structure of high-speed speed railways has been gaining considerations by many researchers due to its coupled merits of the strength of cement as well as the flexibility of asphalt material. The asphalt to cement ratio (A/C) and the compatibility among constituent materials are crucial to the properties of CA mortar. To improve the performance properties and application of CA mortar, it is imperative to have a broad understanding of the composition mechanisms and compatibility between constituent materials. This paper summarizes interesting research outcomes related to the composition and properties of CA mortar. The consumption of water by cement promotes the breakdown of emulsified asphalt, likewise, the adsorption of asphalt droplets on the surface of cement grains retards the hydration process of cement. An appropriate A/C is required for the cement hydration rate to match the speed of demulsification of asphalt emulsion. Depending on the type and properties for which the CA mortar is designed to possess, the A/C ranges from 0.2 to 0.6 for type 1 (CAM I), and 0.6 to 1.2 for type 2 (CAM II). This paper also discusses measures taken to improve performance properties, compatibility, the interaction between constituent materials of CA mortar, and the use of additives as a partial replacement of cement in CA mortar production. The current review also suggests areas of interest for future research studies. This paper is useful to those who aim to understand or study the composition mechanisms and performance properties of CA mortar.

Effect of Emulsified Asphalt on Temperature Susceptibility of Cement Asphalt Mortar

2011 ◽  
Vol 335-336 ◽  
pp. 124-127 ◽  
Author(s):  
Yun Hua Zhang ◽  
Fa Zhou Wang
Keyword(s):  
Asphalt Emulsion ◽  
Thermal Dependence ◽  
Temperature Range ◽  
Cement Asphalt Mortar ◽  
Different Temperatures ◽  
Lower Temperature ◽  
Emulsified Asphalt ◽  
Temperature Susceptibility ◽  
Ca Mortar ◽  
Asphalt Mortar

Cement asphalt mortar (CA mortar, or CAM) is a composite material with equal presence of cement and asphalt emulsion and acts as a cushion layer in the structure of slab track. In the hardened matrix, asphalt accounts for about 30 vol. %, rendering the properties of CA mortar susceptible to temperature variation. In the paper, different kinds of emulsified asphalts (A70 emulsified asphalt, A90 emulsified asphalt, SBS modified emulsified asphalt and SBR modified emulsified asphalt) for CA mortar and the compressive strengths of CA mortar under different temperatures (-18°C, 10°C, 25°C, 40°C and 60°C) were studied to reflect its thermal dependence. Results indicate that temperature susceptibility of CA mortar prepared with modified emulsified asphalt is better than which prepared with unmodified emulsified asphalt. SBS modified emulsified asphalt -CAM (viz. CA mortar prepared by SBS modified emulsified asphalt) is alleviated at the whole temperature range, while that of SBR modified emulsified asphalt -CAM is improved primarily at the lower temperature region. As for types of unmodified asphalts, A90 emulsified asphalt -CAM outperforms A70 emulsified asphalt -CAM at lower temperature range.

Research on Performance of CRTS I Cement-Emulsified Asphalt Mortar on Site

2017 ◽  
Vol 1142 ◽  
pp. 334-339
Author(s):  
Heng Qiong Jia ◽  
Tao Wang ◽  
Zhao Wei
Keyword(s):  
High Speed ◽  
Pore Diameter ◽  
Woven Fabrics ◽  
High Speed Railway ◽  
Ballastless Track ◽  
Emulsified Asphalt ◽  
Internal Pore ◽  
Ca Mortar ◽  
Asphalt Mortar ◽  
Track Slab

For construction method of infusion bag, expansion of CRTSⅠCA mortar on site by core drilling, water absorption, chloride ion permeability and frost resistance and other properties were studied in comparison with performance of mortar in laboratory under standard curing. The results showed that expansion of the mortar on site was 2%, water absorption was 0.5%, charge amount was 210C, quality loss after 300 freeze-thaw cycles was -1.1%, the performance was much better than molded mortar in laboratory. Pore structure analysis showed that the internal pore diameter of the mortar on site was about 150μm, pore content was 9% to 12%; the internal pore diameter of the mortar in laboratory was also about 150μm, pore content was 10% to 15%. China railway track system（CRTSⅠ）slab ballastless track is one of the main structure forms of the modern high-speed railway and mainly composed of concrete basement, the Cement-emulsified Asphalt Mortar layer and concrete slab, featured by its rapid construction, convenient maintenance, and so on, has been widely applied in high-speed railway construction in our country. The cement-emulsified asphalt（CA） Mortar is one of the key materials and structures in slab ballastless track, providing the appropriate stiffness and elasticity which is usually composed of cement, emulsified asphalt, grit, water and many types of additives, containing a variety of inorganic/organic compositions and many types of surfactants, through the special bag, filling inside the flat cavity by its own weight between track slab and concrete basement with a thickness of 50mm (length×width 4962 mm×2400 mm). The construction method of CA mortar is grouting the non-woven fabrics bag after setting the bag under the track slab fixed by fine adjustment claw, which is convenient and has no requirement of mould removal. The bag is fixed before the perfusion process and does not produce wrinkles. The method greatly enhances the construction efficiency and has been widely utilized in high-speed railway. To full perfusion and tightness with track board, CA mortar contains gas former and expands after the end of infusion in a restricted state. Non-woven fabrics bag itself with breathable permeable, a small amount of water seeps around infusion bags in a period of time after the end of the infusion. Theoretically free water seepage of mortar on the one hand increases the compactness and durability of the mortar, but on the other hand will reduce the mortar expansion; the quality of filling layer mortar can meet the acceptance requirements in the engineering practice. In the same raw materials and mortar mixing, the performance of fresh mortar can require CRTSⅠ type of slab track emulsified asphalt cement mortar in high-speed railway Q / CR 469-2015. After water seepage performance of hardening mortar on site is different from laboratory mortar, because the surface of laboratory mortar is without compression and free deformation. In this paper, contrast mortar on site and molded mortar in laboratory, the performance of hardened mortar on site were studied.

New Frontiers of Body Composition in Sport

2021 ◽  
Author(s):  
Henry Lukaski ◽  
Christiana J. Raymond-Pope
Keyword(s):  
Body Composition ◽  
Measurement Errors ◽  
Return To Sport ◽  
Bioelectrical Impedance ◽  
The Body ◽  
Future Research ◽  
Regional Body Composition ◽  
And Performance ◽  
Areas Of Interest ◽  
Composition Measurements

AbstractThe body composition phenotype of an athlete displays the complex interaction among genotype, physiological and metabolic demands of a sport, diet, and physical training. Observational studies dominate the literature and describe the sport-specific physique characteristics (size, shape, and composition) of adult athletes by gender and levels of competition. Limited data reveal how body composition measurements can benefit an athlete. Thus, the objective is to identify purposeful measurements of body composition, notably fat and lean muscle masses, and determine their impact on the health and performance of athletes. Areas of interest include relationships among total and regional body composition measurements, muscle function, sport-specific performance, risk of injury, return to sport after injury, and identification of activity-induced fluid shifts. Discussion includes the application of specific uses of dual X-ray absorptiometry and bioelectrical impedance including an emphasis on the need to minimize measurement errors and standardize protocols, and highlights opportunities for future research. This focus on functional body composition can benefit the health and optimize the performance of an athlete.

Study on SBS Modified Asphalt Emulsion and Aggregate Adhesion of CA Mortar

2011 ◽  
Vol 413 ◽  
pp. 467-471 ◽  
Author(s):  
Bao Ju Liu ◽  
Shao Ying Ning ◽  
Yuan Xia Yang
Keyword(s):  
Zeta Potential ◽  
Isoelectric Point ◽  
Asphalt Emulsion ◽  
Absolute Value ◽  
Modified Asphalt ◽  
Emulsified Asphalt ◽  
Sbs Modified Asphalt ◽  
Influence Of Ph ◽  
Ca Mortar ◽  
Better Than

The influence of pH of emulsified asphalt, the kinds and content of emulsifiers and stabilizers on asphalt-aggregate adhesion have been investigated in this paper. Results show that the pH of the emulsified asphalt has great impact on asphalt-aggregate adhesion by way of the effect of pH on asphalt, asphalt-aggregate adhesion is worst when asphalt emulsion at pH≈4, which is close to the isoelectric point of asphalt, the bigger the zeta potential absolute value of emulsified asphalt, the better the asphalt-aggregate adhesion property. Effect of emulsifiers on asphalt-aggregate adhesion is complex, the best dosage is at 0.2%. The addition of organic stabilizers are superior to inorganic stabilizers to improve the asphalt-aggregate adhesion, the best dosage is at 0.4%. Effect of mixing emulsifier and stabilizer is better than single-doped emulsifier and stabilizer.

Field Testing of Concrete Crossties and Fastening Systems for the Understanding of Mechanistic Behavior

2013 ◽  
Author(s):  
J. Grassé ◽  
D. Lange
Keyword(s):  
High Speed ◽  
Field Testing ◽  
Element Model ◽  
Future Research ◽  
Load Path ◽  
High Speed Rail ◽  
Railway Infrastructure ◽  
Field Experimentation ◽  
And Performance ◽  
The University

To adequately satisfy the demands placed on North America’s railway infrastructure through ever increasing freight tonnages and development of its high speed rail program, the design and performance of concrete ties and elastic fastening systems must be improved. As a part of a study funded by the Federal Railroad Administration (FRA) aimed at improving concrete crossties and fastening systems, field experimentation was performed at the Transportation Technology Center (TTC) in Pueblo, CO by researchers from the University of Illinois at Urbana-Champaign (UIUC). This paper details the extensive instrumentation program which includes strain gages and linear potentiometers. Testing was conducted over seven adjacent concrete crossties in tangent and curve track utilizing TTC’s Track Loading Vehicle (TLV) as well as passenger and freight train consists. Measurements taken consisted of the wheel-rail input loads, component stresses (e.g. insulator post compression), concrete tie strains, and displacements of the rail and concrete tie. The data was collected synchronously to provide a means to capture the load path, target areas of uncertainty, and provide comprehensive data for the validation of a multi-tie, 3-D finite element model being developed by UIUC. Varying train speeds, track curvature, and loading types provided a means to assess the loading variability that can be expected within the fastening system and lead to more purposeful and efficient instrumentation strategies. Furthermore, this data can be used to guide future research in further quantifying the field loading demands on system components, ultimately leading to the mechanistic design of the concrete crosstie and fastening system.

Dynamic Mechanical Analysis of CRTS II Cement Asphalt Mortar

2014 ◽  
Vol 584-586 ◽  
pp. 1646-1651
Author(s):  
Hua Yang Zhang ◽  
Long Hua Yuan ◽  
De Wei Ren
Keyword(s):  
Viscoelastic Properties ◽  
High Speed ◽  
Mechanical Analysis ◽  
Asphalt Emulsion ◽  
High Speed Railway ◽  
Burgers Model ◽  
Cement Asphalt Mortar ◽  
Different Temperatures ◽  
Ca Mortar ◽  
Asphalt Mortar

Cement asphalt mortar (CA mortar) is one of key structures of slab ballastless high-speed railway. Cement and asphalt emulsion are the main two components of CA mortar, making it possess the viscoelastic properties of viscoelastic materials, which is one of the infancy of the current study. In this paper, DMA method was adopted to investigate the viscoelastic properties of CRTS II CA mortar. Viscoelastic properties of CA mortar at different temperatures were investigated and were compared with the numerical simulation results of Burgers model. The results of the simulation fit in well with the data from the experimental-scale column, so we can study the dynamic modulus of CA mortar using the Burgers model in the temperature range of CA mortar.

Research on High-Speed Cutting of Cr12MoV Hardened Steel - A Review

2020 ◽  
Vol 15 ◽  
Author(s):  
Fei Sun ◽  
Guohe Li ◽  
Qi Zhang ◽  
Meng Liu
Keyword(s):  
High Speed ◽  
Cutting Temperature ◽  
High Hardness ◽  
High Strength ◽  
Hardened Steel ◽  
Parameters Optimization ◽  
Future Research ◽  
High Speed Machining ◽  
Machined Surface ◽  
Stamping Die

: Cr12MoV hardened steel is widely used in the manufacturing of stamping die because of its high strength, high hardness, and good wear resistance. As a kind of mainstream cutting technology, high-speed machining has been applied in the machining of Cr12MoV hardened steel. Based on the review of a large number of literature, the development of high-speed machining of Cr12MoV hardened steel was summarized, including the research status of the saw-tooth chip, cutting force, cutting temperature, tool wear, machined surface quality, and parameters optimization. The problems that exist in the current research were discussed and the directions of future research were pointed out. It can promote the development of high-speed machining of Cr12MoV hardened steel.

Review of Research on Hydrostatic Bearings

2020 ◽  
Vol 13 ◽  
Author(s):  
Xiaodong Yu ◽  
Yu Wang ◽  
Junfeng Wang ◽  
Wenkai Zhou ◽  
Hongwei Bi ◽  
...  
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Development Trend ◽  
Cnc Machining ◽  
Pressure Effects ◽  
Cnc Machine Tools ◽  
Future Research ◽  
Theoretical Formula ◽  
Hydrostatic Bearing ◽  
Hydrostatic Bearings

Background: Hydrostatic bearings have the advantages of strong bearing capacity, good stability, small friction coefficient and long life. The performance of liquid hydrostatic bearings directly affect the accuracy and efficiency of CNC machining equipment. The performance is conducive to the development of CNC machine tools towards high speed and heavy load, so it is necessary to sort out and summarize the existing research results. Objective: This study summarizes the current development status of hydrostatic bearings and explains the development trend of hydrostatic bearings. Methods: According to the recently published journal articles and patents, the recent experimental research on hydrostatic thrust bearings is summarized. This paper summarizes many factors that affect the performance of hydrostatic bearings, and discusses the causes of various factors on hydrostatic bearings. Finally, future research on hydrostatic bearings is presented. Results: The study discusses experimental methods, simulation processes, and experimental results. Conclusion: This study can produce dynamic and static pressure effects by changing the structure of the oil cavity of the hydrostatic bearing. This effect can make up for the static pressure loss. By improving the theoretical formula and mathematical model and proposing a new simulation method, the accuracy of the hydrostatic bearing simulation is satisfied; the future development trend of the hydrostatic bearing is proposed.

ANTECEDENTS AND CONSEQUENCES OF ORGANIZATIONAL JUSTICE

2016 ◽  
Vol 12 (02) ◽  
Author(s):  
Reeta Yadav
Keyword(s):  
Job Satisfaction ◽  
Organizational Justice ◽  
Organizational Citizenship ◽  
Organizational Citizenship Behavior ◽  
Turnover Intentions ◽  
Research Work ◽  
Citizenship Behavior ◽  
Future Research ◽  
Antecedents And Consequences ◽  
And Performance

Employee’s perception regarding fairness in the organization is termed as organizational justice. The objective of this paper is to study the antecedents and consequences of organizational justice on the basis of earlier relevant studies from the period ranging from 1964 to 2015. Previous research identified employee participation, communication, justice climate as the antecedents and trust, job satisfaction, commitment, turnover intentions, organizational citizenship behavior and performance as the consequences of organizational justice. Finding reveals the gaps existing in the literature and gives suggestions for future research work.

Sign in / Sign up

Export Citation Format

Share Document