scholarly journals Fracture Models and Effect of Fibers on Fracture Properties of Cementitious Composites—A Review

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5495
Author(s):  
Peng Zhang ◽  
Yonghui Yang ◽  
Juan Wang ◽  
Meiju Jiao ◽  
Yifeng Ling
Keyword(s):  
Cementitious Composites ◽  
Band Model ◽  
Crack Model ◽  
Cementitious Composite ◽  
Fracture Properties ◽  
Crack Band ◽  
The Matrix ◽  
Fictitious Crack ◽  
Pseudo Strain Hardening ◽  
Pva Fiber

Cementitious composites have good ductility and pseudo-crack control. However, in practical applications of these composites, the external load and environmental erosion eventually form a large crack in the matrix, resulting in matrix fracture. The fracture of cementitious composite materials causes not only structural insufficiency, but also economic losses associated with the maintenance and reinforcement of cementitious composite components. Therefore, it is necessary to study the fracture properties of cementitious composites for preventing the fracture of the matrix. In this paper, a multi-crack cracking model, fictitious crack model, crack band model, pseudo-strain hardening model, and double-K fracture model for cementitious composites are presented, and their advantages and disadvantages are analyzed. The multi-crack cracking model can determine the optimal mixing amount of fibers in the matrix. The fictitious crack model and crack band model are stress softening models describing the cohesion in the fracture process area. The pseudo-strain hardening model is mainly applied to ductile materials. The double-K fracture model mainly describes the fracture process of concrete. Additionally, the effects of polyvinyl alcohol (PVA) fibers and steel fibers (SFs) on the fracture properties of the matrix are analyzed. The fracture properties of cementitious composite can be greatly improved by adding 1.5–2% PVA fiber or 4% steel fiber (SF). The fracture property of cementitious composite can also be improved by adding 1.5% steel fiber and 1% PVA fiber. However, there are many problems to be solved for the application of cementitious composites in actual engineering. Therefore, further research is needed to solve the fracture problems frequently encountered in engineering.

A Comparison of Cohesive Crack Model and Crack Band Model in Concrete Fracture

2012 ◽  
Vol 170-173 ◽  
pp. 3375-3380
Author(s):  
Liang Wu ◽  
Ze Li ◽  
Shang Huang
Keyword(s):  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Opening ◽  
Cohesive Crack ◽  
Band Model ◽  
Crack Model ◽  
Concrete Fracture ◽  
Cohesive Crack Model ◽  
Crack Band

The cohesive crack model and the crack band model are two convenient approaches in concrete fracture analysis. They can describe in full the fracture process by the different manner: The entire fracture process zone is lumped into the crack line and is characterized in the form of a stress-displacement law which exhibits softening; or the inelastic deformations in the fracture process zone are smeared over a band of a certain width, imagined to exist in front of the main crack. The correlation of the two models is developed based on a characteristic width of crack band. The analysis shows that they can yield about the same results if the crack opening displacement in the cohesive crack model is taken as the fracturing strain that is accumulated over the width of the crack band model. Some basic problems are also discussed in finite element analysis.

scholarly journals Effect of PVA fiber on durability of cementitious composite containing nano-SiO2

2019 ◽  
Vol 8 (1) ◽  
pp. 116-127 ◽  
Author(s):  
Peng Zhang ◽  
Qing-fu Li ◽  
Juan Wang ◽  
Yan Shi ◽  
Yi-feng Ling
Keyword(s):  
Volume Fraction ◽  
Fiber Content ◽  
Nano Particles ◽  
Cementitious Composites ◽  
Cementitious Composite ◽  
Fiber Reinforced ◽  
Cracking Resistance ◽  
Carbonation Resistance ◽  
Pva Fiber

Abstract In the current investigation, the influence of polyvinyl alcohol (PVA) fibers on flowability and durability of cementitious composite containing fly ash and nano-SiO2 was evaluated. PVA fibers were added into the composite at a volume fraction of 0.3%, 0.6%, 0.9%, and 1.2%. The flowability of the fresh cementitious composite was assessed using slump flow. The durability of cementitious composite includes carbonation resistance, permeability resistance, cracking resistance as well as freezing-thawing resistance, which were evaluated by the depth of carbonation, the water permeability height, cracking resistance ratio of the specimens, and relative dynamic elastic modulus of samples after freeze-thaw cycles, respectively. The results indicated that addition of PVA fibers had a little disadvantageous influence on flowability of cementitious composite, and the flowability of the fresh mixtures decreased with increases in PVA fiber content. Incorporation of PVA fibers significantly improved the durability of cementitious composites regardless of addition of nano-particles. When the fiber content was less than 1.2%, the durability indices of permeability resistance and cracking resistance increased with fiber content. However, the durability indices of carbonation resistance and freezing-thawing resistance began to decrease as the fiber dosage increased from 0.9% to 1.2%. The fiber reinforced cementitious composite exhibited better durability due to addition of nano-SiO2 particles. Nano-SiO2 particle improves microscopic structure of fiber reinforced cementitious composites, and the nano-particles are beneficial for PVA fibers to play the role of reinforcement in cementitious composites.

Micromechanical Progressive Failure Analysis of Fiber-Reinforced Composite Using Refined Beam Models

2017 ◽  
Vol 85 (2) ◽  
Author(s):  
I. Kaleel ◽  
M. Petrolo ◽  
A. M. Waas ◽  
E. Carrera
Keyword(s):  
Failure Analysis ◽  
Progressive Failure ◽  
Computational Cost ◽  
Band Model ◽  
Beam Model ◽  
Fiber Reinforced ◽  
Band Theory ◽  
Progressive Failure Analysis ◽  
Crack Band ◽  
The Matrix

An efficient and novel micromechanical computational platform for progressive failure analysis of fiber-reinforced composites is presented. The numerical framework is based on a recently developed micromechanical platform built using a class of refined beam models called Carrera unified formulation (CUF), a generalized hierarchical formulation which yields a refined structural theory via variable kinematic description. The crack band theory is implemented in the framework to capture the damage propagation within the constituents of composite materials. The initiation and orientation of the crack band in the matrix are determined using the maximum principal stress state and the traction-separation law governing the crack band growth is related to the fracture toughness of the matrix. A representative volume element (RVE) containing randomly distributed fibers is modeled using the component-wise (CW) approach, an extension of CUF beam model based on Lagrange type polynomials. The efficiency of the proposed numerical framework is achieved through the ability of the CUF models to provide accurate three-dimensional (3D) displacement and stress fields at a reduced computational cost. The numerical results are compared against experimental data available in the literature and an analogous 3D finite element model with the same constitutive crack band model. The applicability of CUF beam models as a novel micromechanical platform for progressive failure analysis as well as the multifold efficiency of CUF models in terms of CPU time are highlighted.

scholarly journals Compressive Strength Prediction of PVA Fiber-Reinforced Cementitious Composites Containing Nano-SiO2 Using BP Neural Network

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 521 ◽  
Author(s):  
Ting-Yu Liu ◽  
Peng Zhang ◽  
Juan Wang ◽  
Yi-Feng Ling
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Compressive Strength ◽  
Bp Neural Network ◽  
Cementitious Composites ◽  
Cementitious Composite ◽  
Fiber Reinforced ◽  
Nano Sio2 ◽  
Pva Fiber ◽  
Fiber Reinforced Cementitious Composites

In this study, a method to optimize the mixing proportion of polyvinyl alcohol (PVA) fiber-reinforced cementitious composites and improve its compressive strength based on the Levenberg-Marquardt backpropagation (BP) neural network algorithm and genetic algorithm is proposed by adopting a three-layer neural network (TLNN) as a model and the genetic algorithm as an optimization tool. A TLNN was established to implement the complicated nonlinear relationship between the input (factors affecting the compressive strength of cementitious composite) and output (compressive strength). An orthogonal experiment was conducted to optimize the parameters of the BP neural network. Subsequently, the optimal BP neural network model was obtained. The genetic algorithm was used to obtain the optimum mix proportion of the cementitious composite. The optimization results were predicted by the trained neural network and verified. Mathematical calculations indicated that the BP neural network can precisely and practically demonstrate the nonlinear relationship between the cementitious composite and its mixture proportion and predict the compressive strength. The optimal mixing proportion of the PVA fiber-reinforced cementitious composites containing nano-SiO2 was obtained. The results indicate that the method used in this study can effectively predict and optimize the compressive strength of PVA fiber-reinforced cementitious composites containing nano-SiO2.

scholarly journals Experimental Investigation on Dynamic Tensile Behaviors of Engineered Cementitious Composites Reinforced with Steel Grid and Fibers

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7042
Author(s):  
Liang Li ◽  
Hongwei Wang ◽  
Jun Wu ◽  
Shutao Li ◽  
Wenjie Wu
Keyword(s):  
Energy Dissipation ◽  
Strain Rate ◽  
Peak Stress ◽  
Cementitious Composites ◽  
Failure Behavior ◽  
Engineered Cementitious Composites ◽  
Volume Fractions ◽  
Kevlar Fiber ◽  
The Matrix ◽  
Pva Fiber

Engineered cementitious composites (ECC) used as runway pavement material may suffer different strain rate loads such as aircraft taxiing, earthquakes, crash impacts, or blasts. In this paper, the dynamic tensile behaviors of the steel grid-polyvinyl alcohol (PVA) fiber and KEVLAR fiber-reinforced ECC were investigated by dynamic tensile tests at medium strain rates. The mixture was designed with different volume fractions of fibers and layer numbers of steel grids to explore the reinforcement effectiveness on the dynamic performance of the ECC. The volume fractions of these two types of fibers were 0%, 0.5%, 1%, 1.5%, and 2% of the ECC matrix, respectively. The layer numbers of the steel grid were 0, 1, and 2. The dynamic tensile behaviors of the PVA fiber and the KEVLAR fiber-reinforced ECC were also compared. The experimental results indicate that under dynamic tensile loads, the PVA-ECC reveals a ductile and multi-cracking failure behavior, and the KEVLAR-ECC displays a brittle failure behavior. The addition of the PVA fiber and the KEVLAR fiber can improve the tensile peak stress of the ECC matrix. For the specimens A0.5, A1, A1.5, and A2.0, the peak stress increases by 84.3%, 149.4%, 209.6%, and 237.3%, respectively, compared to the matrix specimen. For the specimens K0.5, K1, K1.5, and K2, the peak stress increases by about 72.3%, 147.0%, 195.2%, and 263.9%, respectively, compared to the matrix specimen. The optimum fiber volume content is 1.5% for the PVA-ECC and the KEVLAR-ECC. The KEVLAR-ECC can supply a higher tensile strength than the PVA-ECC, but the PVA-ECC reveals more prominent deformation capacity and energy dissipation performance than the KEVLAR-ECC. Embedding steel grid can improve the tensile peak stress and the energy dissipation of the ECC matrix. For the strain rate of 10−3 s−1, the peak stress of the A0.5S1 and A0.5S2 specimens increases by about 49.1% and 105.7% compared to the A0.5 specimen, and the peak stress of the K0.5S1 and K0.5S2 specimens increases by about 61.5% and 95.8%, respectively, compared to the K0.5 specimen.

Compressive Strength and Flexural Properties of High Performance Nano-Binder Cementitious Composites

2013 ◽  
Vol 275-277 ◽  
pp. 2064-2068 ◽  
Author(s):  
Xiang Gao ◽  
Qing Hua Li ◽  
Shi Lang Xu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Performance ◽  
Flexural Properties ◽  
Cementitious Composites ◽  
Nano Sio2 ◽  
The Matrix ◽  
Average Crack ◽  
Sio2 Particles ◽  
Pva Fiber

High performance nano-binder cementitious composites (HPNCC) are ultra-ductile fiber reinforced cementitious composites with special matrix. The compressive strength and flexural properties of HPNCC containing nano-SiO2 particles were investigated at age of 3d, 7d, 14d and 28d. According to the results, HPNCC exhibited excellent mechanical properties in the test. The compressive strength, flexural strength and first crack strain of HPNCC were all increased obviously at early age except the ultimate strain. In the flexural test, both crack extension width and the number of fine cracks decrease along with the curing age. However, the average crack spacing has no remarkable changes. Nano-SiO2 particles in HPNCC acted as ultra-fine fillers and catalyzers to strengthen the interfacial bond between the matrix and PVA fiber which improved the mechanical properties and would make HPNCC be widely used in the engineering.

scholarly journals Effect of Modified Polyvinyl Alcohol Fibers on the Mechanical Behavior of Engineered Cementitious Composites

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 37 ◽  
Author(s):  
Mian Sun ◽  
Youzhi Chen ◽  
Jiaoqun Zhu ◽  
Tao Sun ◽  
Zhonghe Shui ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Polyvinyl Alcohol ◽  
Performance Improvement ◽  
Fracture Resistance ◽  
Cementitious Composites ◽  
Cementitious Composite ◽  
Engineered Cementitious Composites ◽  
Engineered Cementitious Composite ◽  
Pressure Resistance ◽  
Pva Fiber

：Polyvinyl alcohol (PVA) fiber was proposed to enhance the mechanical performance of engineered cementitious composite in this research. A mixture of engineered cementitious composite with better expected performance was made by adding 2% PVA fiber. Mechanics tests, including pressure resistance, fracture resistance, and ultimate tensile strength, were conducted. They reveal that the engineered cementitious composites not only exhibit good pressure resistance, but they also exhibit excellent fracture resistance and strain capability against tensile stress through mechanics tests, including pressure resistance, fracture resistance, and ultimate tensile resistance. To further improve the engineered composites’ ductility, attempts to modify the performance of the PVA fiber surface have been made by using a vinyl acetate (VAE) emulsion, a butadiene–styrene emulsion, and boric anhydride. Results indicated that the VAE emulsion achieved the best performance improvement. Its use in fiber pre-processing enables the formation of a layer of film with weak acidity, which restrains the hydration of adjacent gel materials, and reduces the strength of transitional areas of the fiber/composite interface, which restricts fiber slippage and pulls out as a result of its growth in age, and reduces hydration levels. Research illustrates that the performance-improvement processing that is studied not only improves the strain of the engineered cementitious composites, but can also reduce the attenuation of the strain against tensile stress.

Macro- to Atomic-Scale Tailoring of Si3N4 Ceramics to Enhance Properties

2005 ◽  
Vol 287 ◽  
pp. 233-241 ◽  
Author(s):  
Paul F. Becher ◽  
Gayle S. Painter ◽  
Naoya Shibata ◽  
Hua Tay Lin ◽  
Mattison K. Ferber
Keyword(s):  
Electronic Device ◽  
Atomic Level ◽  
Atomic Scale ◽  
Fracture Properties ◽  
Beta Particles ◽  
Preferential Segregation ◽  
Nitride Ceramics ◽  
Theoretical Predictions ◽  
The Matrix

Silicon nitride ceramics are finding uses in numerous engineering applications because of their tendency to form whisker-like microstructures that can overcome the inherent brittle nature of ceramics. Studies now establish the underlying microscopic and atomic-scale principles for engineering a tough, strong ceramic. The theoretical predictions are confirmed by macroscopic observations and atomic level characterization of preferential segregation at the interfaces between the grains and the continuous nanometer thick amorphous intergranular film (IGF). Two interrelated factors must be controlled for this to occur including the generation of the elongated reinforcing grains during sintering and debonding of the interfaces between the reinforcing grains and the matrix. The reinforcing grains can be controlled by (1) seeding with beta particles and (2) the chemistry of the additives, which also can influence the interfacial debonding conditions. In addition to modifying the morphology of the reinforcing grains, it now appears that the combination of preferential segregation and strong bonding of the additives (e.g., the rare earths, RE) to the prism planes can also result in sufficiently weakens the bond of the interface with the IGF to promote debonding. Thus atomic-scale engineering may allow us to gain further enhancements in fracture properties. This new knowledge will enable true atomic-level engineering to be joined with microscale tailoring to develop the advanced ceramics that will be required for more efficient engines, new electronic device architectures and composites.

Matrix design for pseudo-strain-hardening fibre reinforced cementitious composites

1995 ◽  
Vol 28 (10) ◽  
pp. 586-595 ◽  
Author(s):  
Victor C. Li ◽  
Dhanada K. Mishra ◽  
Hwai-Chung Wu
Keyword(s):  
Strain Hardening ◽  
Cementitious Composites ◽  
Pseudo Strain Hardening ◽  
Matrix Design
Sign in / Sign up

Export Citation Format

Share Document