scholarly journals Durability of Textile Reinforced Concrete: Existing Knowledge and Current Gaps

2021 ◽  
Vol 11 (6) ◽  
pp. 2771
Author(s):  
Mohammad Alma’aitah ◽  
Bahman Ghiassi ◽  
Ali Dalalbashi
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Performance ◽  
Mechanical Tests ◽  
Textile Reinforced Concrete ◽  
Standard Procedures ◽  
Long Term Performance ◽  
Term Performance ◽  
Existing Data

This paper aims to provide a review of the current literature on the durability of textile-reinforced concrete and mortar (TRC/TRM) composites. Most previous studies have focused on the role of chemical attacks, freeze-thaw conditions, and high temperatures on the mechanical performance of these composites. Information on the long-term performance of TRCs under synergistic action of mechanical and environmental loads is scarce. Considering the variety of fabrics and matrices used for the production of TRC composites, the existing data are still very limited and comprehensive studies are needed in this field. Additionally, due to the lack of standard procedures, different approaches are often followed for durability or post-ageing mechanical tests, or sufficient data on the curing and post-ageing preparation procedures followed are not provided. These have led to incompatibility of the existing data and in some cases contradictory results on the durability of these materials.

Analysis of thermo-mechanical coupling damage behavior in long-term performance of microelectromechanical systems actuators

2021 ◽  
pp. 105678952110339
Author(s):  
Jiaxing Cheng ◽  
Zhaoxia Li
Keyword(s):  
Damage Mechanics ◽  
Microelectromechanical Systems ◽  
Mechanical Performance ◽  
Damage Model ◽  
Irreversible Damage ◽  
Damage Behavior ◽  
Thermal Actuators ◽  
Long Term Performance ◽  
Term Performance

Effective numerical analysis is significant for the optimal design and reliability evaluation of MEMS, but the complexity of multi-physical field couplings and irreversible damage accumulation in long-term performance make the analysis difficult. In the present paper, the continuum damage mechanics method is used to develop a creep damage model and conduct long-term performance analysis for MEMS thermal actuators with coupled thermo-mechanical damage behavior. The developed damage model can make a connection between the material deterioration due to microstructure changes and the macroscopic responses (the change of thermo-mechanical performance or structure failure). The numerical simulations of coupled thermo-mechanical behavior in long-term performance are implemented using the finite element method, which is validated through comparison with previous literature. The numerical results demonstrate that the proposed damage model and numerical method can provide effective assessment in the long-term performance of MEMS thermal actuators.

scholarly journals Design and Construction of Ultra-Thin Continuously Reinforced Concrete (UTCRC) on N1 near Hugenote Tunnell

2018 ◽  
Vol 199 ◽  
pp. 08002
Author(s):  
Steph Bredenhann ◽  
Johan van Heerden ◽  
Pieter Strauss ◽  
Phillip Joubert
Keyword(s):  
Reinforced Concrete ◽  
Material Design ◽  
Performance Comparison ◽  
Base Layer ◽  
Western Cape ◽  
Traffic Loading ◽  
North East ◽  
Long Term Performance ◽  
Term Performance

In 2009, the National Route 1 Section 1 between km 56.1 and km 61.5, located North East of Paarl in the Western Cape Province of South Africa, was rehabilitated and widened. As part of the rehabilitation and widening contract the downhill truck crawler lane was constructed as an experimental pavement section. This experimental pavement section was constructed with a 50 mm thick Ultra-Thin Continuously Reinforced Concrete Pavement (UTCRCP). Early in 2010 sections of the experimental UTCRCP started to fail and consequently necessitated repair. In October 2014 a service provider was appointed for the special maintenance of the truck crawler lane on the National Route 1 Section 1. The project called for the reinstatement of the failed experimental UTCRCP with a re-engineered UTCRCP and a Enrobé à Module Élevé (EME) asphalt base layer with an Ultra-Thin Friction Course (UTFC), at various locations along the southbound (downhill) truck crawler lane. The project objective was specifically formulated to enable a long term performance comparison of both the re-engineered UTCRCP and the EME with UTFC under repeated traffic loading. The focus of this paper is the documentation and assessment of the initial pavement (structural analysis) and material design process, the construction of the UTCRCP, with cognizance of the challenges experienced during construction as well as the initial performance comparison. EME will not be discussed in this paper.

A new test method for evaluating the long-term performance of fiber-reinforced concrete pipes

2019 ◽  
Vol 23 (7) ◽  
pp. 1336-1349 ◽  
Author(s):  
Fouad T Al Rikabi ◽  
Shad M Sargand ◽  
Issam Khoury ◽  
John Kurdziel
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Steel Reinforcement ◽  
Fiber Reinforced Concrete ◽  
Synthetic Fiber ◽  
Concrete Pipes ◽  
Concrete Pipe ◽  
Long Term Performance ◽  
Term Performance

Synthetic fibers have been used recently to minimize the need for steel reinforcement in the concrete pipe to enhance their ductility. However, synthetic fiber has properties that may change over time due to its viscoelastic behavior. The objective of this study is to investigate the long-term performance of fiber-reinforced concrete pipes using a new test frame. A three-dimensional finite element model was created for the long-term testing frame to ensure its compliance with the American Society for Testing and Materials requirement. The finite element results showed that the testing frame successfully transferred the load to the concrete as the pipe cracked at the location where high flexural stresses are expected. Concrete pipe reinforced with synthetic fiber dosage of 9 kg/m3 along the steel reinforcement area of 5.7 cm2/m was tested to evaluate the concrete pipe system performance. The pipe was tested under two load stages for 120 days each. Load stages 1 and 2 included applying 40% and 70% of the ultimate load obtained by the authors in a previous study, respectively. The strain and deflection increased linearly within 5 days of applying the load and then leveled off. The pipe showed a slight increase in the crack width and deflection, indicating that fiber creep did not have a significant impact on the long-term performance of the concrete pipe. Also, it was observed that strain values surpassed those for plain concrete material, suggesting that including synthetic fiber in the concrete pipe mix enhanced the pipe ductility.

The Role of Cement in the Long Term Performance and Premature Failure of Charnley Low Friction Arthroplasties

1986 ◽  
Vol 15 (1) ◽  
pp. 19-22 ◽  
Author(s):  
G H Isaac ◽  
J R Atkinson ◽  
D Dowson ◽  
B M Wroblewski
Keyword(s):  
Premature Failure ◽  
Hip Prostheses ◽  
Acrylic Cement ◽  
A Value ◽  
Articulating Surface ◽  
Long Term Performance ◽  
Term Performance

A number of polyethylene acetabular cups (59) and femoral stems (38) of Charnley hip prostheses were obtained following revision surgery and examined by scanning electron microscopy. In many cases, acrylic cement particles were embedded in the articulating surface of the cups. These particles caused surface pitting. The appearance of the articulating surfaces suggested that some cement had been present from the time of arthroplasty. In other cups there was evidence of cement ingress during the service life. Failure to use sufficient cement at arthroplasty resulted in cavities on the backs of the cups. Many femoral heads had become scratched in vivo, the surface roughness increasing from an initial value less than 0.02 μm Ra to a value on removal of 0.07 μm Ra. The increased roughness increases the amount of wear in the polyethylene sockets. Laboratory tests show that retrieved acrylic cement particles will scratch stainless steel, and it is our conclusion that entrapped cement will damage both components of the prosthesis and may cause premature failure.

scholarly journals Alkali-activated materials: the role of molecular-scale research and lessons from the energy transition to combat climate change

2020 ◽  
Vol 4 ◽  
pp. 110-121 ◽  
Author(s):  
Claire White
Keyword(s):  
Portland Cement ◽  
Financial Incentives ◽  
Field Performance ◽  
Energy Transition ◽  
Combat Climate Change ◽  
Long Term Performance ◽  
Term Performance ◽  
Alkali Activated

Alternative (i.e., non-Portland) cements, such as alkali-activated materials, have gained significant interest from the scientific community due to their proven CO2 savings compared with Portland cement together with known short-term performance properties. However, the concrete industry remains dominated by Portland cement-based concrete. This Letter explores the technical and non-technical hurdles preventing implementation of an alternative cement, such as alkali-activated materials, in the concrete industry and discusses how these hurdles can be overcome. Specifically, it is shown that certain technical hurdles, such as a lack of understanding how certain additives affect setting of alkali-activated materials (and Portland cement) and the absence of long-term in-field performance data of these sustainable cements, can be mitigated via the use of key molecular- and nano-scale experimental techniques to elucidate dominant material characteristics, including those that control long-term performance. In the second part of this Letter the concrete industry is compared and contrasted with the electricity generation industry, and specifically the transition from one dominant technology (i.e., coal) to a diverse array of energy sources including renewables. It is concluded that financial incentives and public advocacy (akin to advocacy for renewables in the energy sector) would significantly enhance uptake of alternative cements in the concrete industry.

Does the Bargaining Power of Vertical Parties Improve or Worsen the Effect of Family Influence on Long-Term Performance?

2020 ◽  
pp. 154-184
Author(s):  
Rubén Martínez-Alonso ◽  
María J. Martínez-Romero ◽  
Julio Diéguez-Soto ◽  
Alfonso A. Rojo-Ramírez
Keyword(s):  
Environmental Factor ◽  
Bargaining Power ◽  
Manufacturing Firms ◽  
Family Influence ◽  
Negative Effect ◽  
Long Term Performance ◽  
Term Performance ◽  
Moderating Role

Grounding in the socioemotional wealth approach, this chapter explores the effect of family influence on long-term performance. Moreover, this study also examines the moderating role of the bargaining power of vertical parties, namely supplier (SBP) and customer (CBP) bargaining power, on the preceding relationship. By utilising a panel dataset of 3,118 observations of Spanish private manufacturing firms in the 2007–2016 period, the chapter finds that family influence negatively impacts long-term performance. The findings also reveal that CBP mitigates the negative effect of family influence on long-term performance. In this light, CBP is found to be a potential environmental factor that enables family influenced firms enhancing their long-term performance.

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