scholarly journals Cementitious Composites Reinforced with Polypropylene, Nylon and Polyacrylonitile Fibres

2012 ◽  
Vol 730-732 ◽  
pp. 271-276
Author(s):  
H.R. Pakravan ◽  
M. Jamshidi ◽  
M. Latifi ◽  
F. Pacheco-Torgal
Keyword(s):  
Absorption Capacity ◽  
Cement Matrix ◽  
Cementitious Composites ◽  
Scanning Electron Micrographs ◽  
Energy Absorption Capacity ◽  
Cement Ratio ◽  
Pull Out ◽  
Water To Cement Ratio ◽  
Before And After ◽  
Scanning Electron

This paper compares the adhesion strength between three polymeric fibres (polypropylene (PP), nylon66 (N66) and polyacrylonitrile (PAN)) embedded in a cement paste. The specimens were prepared at a water to cement ratio (w/c) of 0.5 and tested after 7, 14 and 28 curing days. It was found that although the adhesion between the polymeric fibres to the cement matrix is an important factor, the energy absorption capacity or energy dissipation ability of the fibres, plays a more important role in the improvement of the cementitious composites fracture toughness. Scanning electron micrographs were used to characterize the fibres surface before and after the Pull-out tests.

scholarly journals Enhancement of Energy Absorption Capacity of Polyethylene Fiber-Reinforced Cementitious Composites According to Admixtures and Curing Conditions

2020 ◽  
Vol 20 (1) ◽  
pp. 319-325
Author(s):  
Min-Jae Kim ◽  
Hong-Joon Choi ◽  
Booki Chun ◽  
Wonsik Shin ◽  
Doo-Yeol Yoo
Keyword(s):  
Compressive Strength ◽  
Tensile Test ◽  
Energy Absorption ◽  
Absorption Capacity ◽  
Limestone Powder ◽  
Cementitious Composites ◽  
Energy Absorption Capacity ◽  
Curing Conditions ◽  
Direct Tensile ◽  
Direct Tensile Test

This study aims to enhance the energy absorption capacity of cementitious composites with 2 vol.% of polyethylene fibers, by adjusting mixing ingredients and curing conditions. Ground blast furnace slag, cement kiln dust, limestone powder, and silica fume were incorporated, and two different curing conditions were applied: 72 h of curing at 90 ℃ and 120 h of curing at 40 ℃. Compressive strength test and direct tensile test were performed on 6 mixtures and the test results were compared with those of ultra-high-performance concrete and engineered cementitious composite specimens. The maximum compressive strength of the 6 mixtures was measured to be approximately 117 MPa. The higher cement replacement ratio of the other components resulted in a decrease in the compressive strength of the specimens cured at 90 ℃. In the direct tensile test, the specimens cured at 40 ℃ exhibited lower tensile strength than those cured at 90 ℃, but the strain capacity was increased by approximately 305% and reached 7.7%. This also resulted in an enhancement of the energy absorption capacity from 80%–292% because of the differences in micro-cracking and fracturing behaviors, such as an increase inthe number of micro-cracks and decrease in crack width.

scholarly journals Effective Absorption Capacity Examined by Isothermal Calorimetry: Effect of Pore Structure and Water-to-Cement Ratio

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Joo-Ha Lee ◽  
Do Guen Yoo ◽  
Bo Yeon Lee
Keyword(s):  
Activated Carbon ◽  
Carbon Fibre ◽  
Pore Structure ◽  
Isothermal Calorimetry ◽  
Absorption Capacity ◽  
Cement Ratio ◽  
Effective Absorption ◽  
Water To Cement Ratio ◽  
Cement Based Materials ◽  
Activated Carbon Fibre

The accurate measurement of effective absorption capacity is crucial for highly absorptive materials when they are used within cement-based materials. In this study, a method for examining effective absorption capacity using isothermal calorimetry is reviewed and investigated in detail to accommodate different circumstances. Specifically, the effect of different pore structures and water-to-cement ratios in determining effective absorption capacity is experimentally examined using activated carbon fibre and powdered activated carbon. The results suggest that the method may be suitable for porous materials with micropores but not suitable for those with mesopores. Also, the results indicate that the effective absorption capacity value can change with the water-to-cement ratio used. These findings can be used to find the effective absorption capacity of highly absorptive materials more accurately using the isothermal calorimetry method.

scholarly journals Impact of High Temperature on the Compressive Strength of ECC

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Xingyan Shang ◽  
Zhoudao Lu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Compressive Strength ◽  
High Temperature ◽  
Microstructural Characterization ◽  
Cementitious Composites ◽  
Strengthening Effect ◽  
Before And After ◽  
Scanning Electron

The influence of different cooling regimes (quenching in water and cooling in air) on the residual mechanical properties of ECC (engineered cementitious composites) exposed to high temperature up to 800°C was discussed in this paper. The specimens quenching in water gained better mechanical properties than the ones cooling in air. The strengthening effect of quenching for specimens subjected to 800°C was more significant than for the ones subjected to 400°C. The microstructural characterization is examined before and after exposure to fire deterioration by using scanning electron microscopy. Results from the microtest well explained the mechanical properties variation of postfire specimens.

Energy absorption capacity of pseudoelastic fiber-reinforced composites

2014 ◽  
Vol 21 (2) ◽  
pp. 173-179
Author(s):  
Mohammad Sayyar ◽  
Anagi M. Balachandra ◽  
Parviz Soroushian
Keyword(s):  
Energy Absorption ◽  
Metal Matrix ◽  
Inelastic Deformation ◽  
Absorption Capacity ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Energy Absorption Capacity ◽  
Deformation And Failure ◽  
Pull Out

AbstractPseudoelastic fiber-reinforced metal matrix composite with enhanced ductility and energy absorption capacity was developed. This composite system relies on the distributed nature of large pseudoelastic strains to mitigate localization of inelastic deformation and failure, and thus mobilizes a major fraction of volume for effective energy absorption. The pseudoelastic fibers were made of Ni-Ti-Cr alloy used in conjunction with two different matrices, aluminum and copper. Tension and pull-out tests were performed to evaluate the ductility and energy absorption capacity of control and pseudoelastic fiber-reinforced composites. Experimental results confirmed the ability of pseudoelastic fibers to induce distributed inelastic deformation within metal matrix composites for realizing major gains in ductility and energy absorption capacity.

The Microstructure of Wood Fiber Reinforced Cementitious Composites

1994 ◽  
Vol 370 ◽  
Author(s):  
X. Lin ◽  
M.R. Silsbee ◽  
D.M. Roy
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Performance ◽  
Wood Fiber ◽  
Cement Matrix ◽  
Cementitious Composites ◽  
Fiber Reinforced ◽  
Wood Fibers ◽  
Fiber Reinforced Cementitious Composites ◽  
Scanning Electron

AbstractWood fiber reinforcing of cement matrices is an economic and an efficient approach to producing high performance cementitious composites. In this study, wood fiber reinforced cementitious composites (WFRCs) were made by using both conventional and novel processing styles. Wood fibers exhibited a considerable ability to improve the flexural strength and the toughness of WFRC when an adequate content of the fibers was used. The morphologies ofvarious type of wood fibers and fracture surface of WFRC were examined by scanning electron microscope (SEM) and an environmental scanning electron microscope (ESEM). The microstructures of wood fiber and WFRC were correlated with their mechanical properties. Results indicate a significant interfacial bonding between the cement matrix and the wood fibers.

Fractographic Observation of Various Loading Modes of Fibre Reinforced Laminates

2012 ◽  
Vol 730-732 ◽  
pp. 337-342 ◽  
Author(s):  
Rosa Marat-Mendes ◽  
Manuel de Freitas
Keyword(s):  
Mixed Mode ◽  
Mode I ◽  
Mode Ii ◽  
Scanning Electron Micrographs ◽  
Mode Iii ◽  
Fibre Breakage ◽  
Pull Out ◽  
Fractographic Features ◽  
Static Conditions ◽  
Scanning Electron

One of the major disadvantages of laminated composites is their tendency to delaminate. Unidirectional glass/epoxy laminates have been tested under static conditions by the use of fracture mechanics. Mode I, mode II, mixed mode I-II, mode III and mixed mode II-III tests were performed. Double cantilever beam (DCB), end-notched flexure (ENF), mixed-mode bending (MMB) and edge crack torsion (ECT) specimens were used. Scanning electron microscopy technique was used to identify distinguishing fractographic features and to establish the differences between the various modes of fracture after specimens testing. The propagated orientation of the delamination could be specified from the patterns of fracture surface. Scanning electron micrographs of fractured surfaces showed that the most predominant fractographic features in mode I and mode II are the large amount of fibre pull-out and the cusps markings respectively. In the MMB specimen the fracture surfaces are characterized by fibre breakage under shearing with fractures localized in the resin with cusps having an orientation of 90º (mode II) and also fractures localized in the resin and along the resin/fibre interface (mode I). Mode III characterization concluded that some limited mixed mode II-III seems to be present for ECT specimen on delamination initiation and growth, but a large majority of mode III delamination is present.

High-Performance Impact-Resistant Concrete Mixture for Transportation Infrastructure Applications

2019 ◽  
Vol 2673 (12) ◽  
pp. 628-635 ◽  
Author(s):  
Kamal Baral ◽  
Jovan Tatar ◽  
Qian Zhang
Keyword(s):  
Energy Absorption ◽  
High Performance ◽  
Impact Resistance ◽  
Absorption Capacity ◽  
Flexural Behavior ◽  
Cementitious Composites ◽  
Repeated Impact ◽  
Energy Absorption Capacity ◽  
Transportation Infrastructures ◽  
The Impact

Engineered cementitious composites (ECC) is a class of high-performance fiber-reinforced cementitious composites featuring metal-like strain-hardening behavior under tension and high ductility. The highly ductile behavior of ECC often results in high impact resistance and energy absorption capacity, which make ECC suitable for applications in structures that are prone to impact damages, like exterior bridge girders, bridge piers, and crash barriers. In a recent study, a new ECC mixture has been developed using domestically available polyvinyl alcohol (PVA) fibers and regular river sand in replacement of imported PVA fibers and fine silica sand that are normally used in other ECC mixtures. The newly developed mixture, with improved local accessibility of raw materials, enables structural-scale applications of ECC in transportation infrastructures. To evaluate the suitability of the mixture for impact-resistant structures, in this paper, the tensile and flexural behavior of the newly developed material were characterized under pseudo-static loading and high strain-rate loadings up to 10−1 s−1. Direct drop-weight impact test was also conducted to assess the impact resistance and energy absorption capacity of the material. It was ensured that the ECC mixture maintains high tensile strain capacity above 1.8% under all tested strain rates. Regarding the damage characteristics, energy absorption capacity and load-bearing capacity during repeated impact loadings, ECC was found to have 75% higher energy dissipation capacity compared with regular reinforced concrete specimens and superior damage tolerance. The research results demonstrated that the newly developed ECC has a great potential to improve the impact resistance of transportation infrastructures.

Effect of Loading Rate on the Bonding Strength between Rebar and Concrete

2012 ◽  
Vol 450-451 ◽  
pp. 122-125 ◽  
Author(s):  
Dong Ming Yan ◽  
Gen Da Chen
Keyword(s):  
Shear Deformation ◽  
Bonding Strength ◽  
Loading Rate ◽  
Load Capacity ◽  
Absorption Capacity ◽  
Energy Absorption Capacity ◽  
Fracture Characteristics ◽  
Pull Out ◽  
Deformation And Fracture ◽  
Concrete Cylinders

In this study, the effect of loading rate on the bonding strength between rebar and concrete substrate is investigated through pull-out test on 24 concrete cylinders. The load capacity, shear deformation and fracture characteristics of the interface are examined carefully. It is found that with the increase of loading rate, the load capacity increases correspondingly and their relationship can be characterized with a semi-logarithm equation. The load-deflection curves expand with the increase of loading rate, which is an indication of a gradually increasing energy absorption capacity with the increase of loading rate. Generally, with higher loading rate, more energy is dissipated.

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