Flexural Behavior and Single Fiber-Matrix Bond-Slip Behavior of Macro Fiber Reinforced Fly Ash-Based Geopolymers

2017 ◽  
pp. 2338-2346 ◽  
Author(s):  
Mohammed Farooq ◽  
Aamer Bhutta ◽  
Paulo H. R. Borges ◽  
Cristina Zanotti ◽  
Nemkumar Banthia
Keyword(s):  
Fly Ash ◽  
Single Fiber ◽  
Flexural Behavior ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Fiber Matrix

scholarly journals Experimental Tests on Fiber-Reinforced Alkali-Activated Concrete Beams Under Flexure: Some Considerations on the Behavior at Ultimate and Serviceability Conditions

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3356
Author(s):  
Linda Monfardini ◽  
Luca Facconi ◽  
Fausto Minelli
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Experimental Results ◽  
Flexural Behavior ◽  
Experimental Program ◽  
Fiber Reinforced ◽  
Limit States ◽  
Structural Applications ◽  
Alkali Activated Concrete ◽  
Alkali Activated

Alkali-activated concrete (AAC) is an alternative concrete typology whose innovative feature, compared to ordinary concrete, is represented by the use of fly ash as a total replacement of Portland cement. Fly ash combined with an alkaline solution and cured at high temperature reacts to form a geopolymeric binder. The growing interest in using AACs for structural applications comes from the need of reducing the global demand of Portland cement, whose production is responsible for about 9% of global anthropogenic CO2 emissions. Some research studies carried out in the last few years have proved the ability of AAC to replace ordinary Portland cement concrete in different structural applications including the construction of beams and panels. On the contrary, few experimental results concerning the structural effectiveness of fiber-reinforced AAC are currently available. The present paper presents the results of an experimental program carried out to investigate the flexural behavior of full-scale AAC beams reinforced with conventional steel rebars, in combination with fibers uniformly spread within the concrete matrix. The experimental study included two beams containing 25 kg/m3 (0.3% in volume) of high-strength steel fibers and two beams reinforced with 3 kg/m3 (0.3% in volume) of synthetic fibers. A reference beam not containing fibers was also tested. The discussion of the experimental results focuses on some aspects significant for the structural behavior at ultimate limit states (ULS) and serviceability limit states (SLS). The discussion includes considerations on the flexural capacity and ductility of the test specimens. About the behavior at the SLS, the influence of fiber addition on the tension stiffening mechanism is discussed, together with the evolution of post-cracking stiffness and of the mean crack spacing. The latter is compared with the analytical predictions provided by different formulations developed over the past 40 years and adopted by European standards.

Investigation of the fiber-matrix interaction in carbon fiber-reinforced polyether ether ketone by cyclic single fiber push-out and push-back tests

2019 ◽  
Vol 27 (2) ◽  
pp. 227-247 ◽  
Author(s):  
Judith Moosburger-Will ◽  
Michael Greisel ◽  
Michael Schulz ◽  
Mario Löffler ◽  
Wolfgang M. Mueller ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Single Fiber ◽  
Fiber Reinforced ◽  
Matrix Interaction ◽  
Polyether Ether Ketone ◽  
Ether Ketone ◽  
Fiber Matrix ◽  
Carbon Fiber Reinforced ◽  
Push Out

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

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