Fracture Toughness of High-Performance Concrete on Three-Point Bending Notched Beams at Elevated Temperature

2010 ◽  
Vol 89-91 ◽  
pp. 159-164 ◽  
Author(s):  
Samira Djaknoun ◽  
Evariste Ouedraogo ◽  
Ali Ahmed Benyahia
Keyword(s):  
Fracture Toughness ◽  
Nuclear Power ◽  
High Performance ◽  
Applied Load ◽  
Thermal Loading ◽  
High Performance Concrete ◽  
Thermal Conditions ◽  
Mechanical Tests ◽  
Bending Test ◽  
Three Point Bending

High-performance concrete (HPC) are advanced materials used in advances applications such as tunnels or nuclear power plant in which they can be accidentally submitted to severe stress or thermal conditions. The present study deals with the material response to thermal loading conditions. The main objective of this research is the characterization of the fracture toughness under Mode I at high temperature of high performance mortars by using notched specimens in three-point bending test in accordance with the RILEM recommendations. The mechanical loading is applied to the specimens while heated at various temperatures ranging from 25 to 900°C in isothermal conditions. The maximum applied load is found to be maximum at 300°C temperature and then to decrease sharply at higher temperatures. Analysis of SEM micrographs undertaken on the heated specimens after mechanical tests helps in the understanding of the material macroscopic behaviour. The evaluation of the material toughness during the hot testing is undertaken through analytical approach based on Fracture Mechanics. Lastly, the stress intensity factor as well as the energy of fracture evolves similarly versus temperature as the maximum applied load.

Effects of Fly Ash Particle Sizes on the Compressive Strength and Fracture Toughness of High Performance Concrete

2011 ◽  
Vol 284-286 ◽  
pp. 984-988
Author(s):  
An Shun Cheng ◽  
Yue Lin Huang ◽  
Chung Ho Huang ◽  
Tsong Yen
Keyword(s):  
Fracture Toughness ◽  
Particle Size ◽  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
Bending Test ◽  
Strength Development ◽  
Particle Sizes

The study aims to research the effect of the particle size of fly ash on the compressive strength and fracture toughness of high performance concrete (HPC). In all HPC mixtures, the water-to-binder ratio selected is 0.35; the cement replacement ratios includes 0%, 10% and 20%; the particle sizes of fly ash have three types of passing through sieves No. 175, No. 250 and No. 325. Three-point-bending test was adopted to measure the load-deflection relations and the maximum loads to determine the fracture energy (GF) and the critical stress intensity factor (KSIC). Test results show that adding fly ash in HPC apparently enhances the late age strengths of HPC either for replacement ratio of 10% or 20%, in which the concrete with 10% fly ash shows the higher effect. In addition, the smaller the particle size is the better the late age concrete strength will be. The HPC with the finer fly ash can have higher strength development and the values of GF and KSIC due to the facts of better filling effect and pozzolanic reaction. At late age, the GF and KSIC values of concrete with 10% fly ash are all higher than those with 20% fly ash.

scholarly journals Damage Assessment using Acoustic Emission on Concrete Beam

2020 ◽  
Vol 9 (3) ◽  
pp. 2977-2981
Keyword(s):  
Acoustic Emission ◽  
Damage Assessment ◽  
High Performance ◽  
High Performance Concrete ◽  
Bending Test ◽  
Ultra High Performance Concrete ◽  
Reliable Technique ◽  
Damage Level ◽  
Three Point Bending ◽  
Selection Of

The selection of reliable technique for damage assessment is important in civil engineering structure. The present study proposed Acoustic emission (AE) technique by using the fundamental AE parameter to evaluate damage accumulated on Ultra High-Performance Concrete (UHPC) specimens. The UHPC beam with dimension of 515 mm x 98 mm x 98 mm was tested under three-point bending test with stepwise flexural load. In order to detect and to collect the AE data, Micro-SAMOS (μ-SAMOS) digital AE system and R6I sensors type were used while data analyses were carried out using AEwin software. The damage level that take place during increasing static loading on tested concrete beams and the mechanism was successfully evaluated using the AE technique.

Mechanical Property and Oxidation Behavior of LPS-SiC Materials

2006 ◽  
Vol 321-323 ◽  
pp. 913-916
Author(s):  
Sang Ll Lee ◽  
Yun Seok Shin ◽  
Jin Kyung Lee ◽  
Jong Baek Lee ◽  
Jun Young Park
Keyword(s):  
Mechanical Property ◽  
Fracture Toughness ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
Indentation Test ◽  
Bending Test ◽  
Secondary Phases ◽  
Three Point Bending ◽  
Different Temperatures

The microstructure and the mechanical property of liquid phase sintered (LPS) SiC materials with oxide secondary phases have been investigated. The strength variation of LPS-SiC materials exposed at the elevated temperatures has been also examined. LPS-SiC materials were sintered at the different temperatures using two types of Al2O3/Y2O3 compositional ratio. The characterization of LPS-SiC materials was investigated by means of SEM with EDS, three point bending test and indentation test. The LPS-SiC material with a density of about 3.2 Mg/m3 represented a flexural strength of about 800 MPa and a fracture toughness of about 9.0 MPa⋅√m.

scholarly journals FDEM Modelling of Rock Fracture Process during Three-Point Bending Test under Quasistatic and Dynamic Loading Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Huaming An ◽  
Yushan Song ◽  
Hongyuan Liu
Keyword(s):  
Fracture Toughness ◽  
Dynamic Loading ◽  
Fracture Process ◽  
Loading Rate ◽  
Rock Fracture ◽  
Mesh Size ◽  
Bending Test ◽  
Loading Conditions ◽  
Three Point Bending ◽  
Dynamic Loading Conditions

A hybrid finite-discrete element method (FDEM) is proposed to model rock fracture initiation and propagation during a three-point bending test under quasistatic and dynamic loading conditions. Three fracture models have been implemented in the FDEM to model the transition from continuum to discontinuum through fracture and fragmentation. The loading rate effect on rock behaviour has been taken into account by the implementation of the relationship between the static and dynamic rock strengths derived from dynamic rock fracture experiments. The Brazilian tensile strength test has been modelled to calibrate the FDEM. The FDEM can well model the stress and fracture propagation and well show the stress distribution along the vertical diameter of the disc during the Brazilian tensile strength test. Then, FDEM is implemented to study the rock fracture process during three-point bending tests under quasistatic and dynamic loading conditions. The FDEM has well modelled the stress and fracture propagation and can obtain reasonable fracture toughness. After that, the effects of the loading rate on the rock strength and rock fracture toughness are discussed, and the mesh size and mesh orientation on the fracture patterns are also discussed. It is concluded that the FDEM can well model the rock fracture process by the implementation of the three fracture models. The FDEM can capture the loading rate effect on rock strength and rock fracture toughness. The FDEM is a valuable tool for studying the rock behaviour on the dynamic loading although the proposed method is sensitive to the mesh size and mesh orientation.

Evaluation of flexural fracture toughness for quasi-brittle structural materials using a simple test method

2002 ◽  
Vol 29 (4) ◽  
pp. 567-575 ◽  
Author(s):  
M.M Reda Taha ◽  
X Xiao ◽  
J Yi ◽  
N G Shrive
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Brittle Fracture ◽  
High Performance ◽  
High Performance Concrete ◽  
Fibre Reinforced Concrete ◽  
Simple Test ◽  
Elastic Crack ◽  
Fracture Performance ◽  
Brittle Fracture Mechanics

As new structural concepts such as partial prestressing and steel-free bridge decks are more widely accepted and used, there is an increasing need for a reliable and reproducible fracture performance criterion that can describe resistance to crack growth. The required criterion should also be easy to determine experimentally so that it can be incorporated in structural specifications. The nonlinear behaviour of concrete and masonry materials suggested that quasi-brittle fracture mechanics approaches may be the most suitable for determining their fracture performance. The effective elastic crack model originally developed by Karihaloo and Nallathambi (1989) was modified to evaluate the critical crack depth under pure flexural stresses. A computer program was developed to calculate this depth iteratively from the experimental results. An experimental programme examining the fracture performance of four different structural materials (high performance concrete, mortar, fibre reinforced concrete, and masonry units) was carried out to examine the applicability of the model. As no post-peak data are required for the analysis, the model allows the use of a simple test setup to evaluate the fracture performance of quasi-brittle materials experimentally.Key words: fracture toughness, linear elastic fracture mechanics (LEFM), elastoplastic fracture mechanics (EPFM), quasi-brittle fracture mechanics, effective elastic crack, high performance concrete, masonry, fibre reinforced concrete.

Assessment of Fracture Toughness Using Small Punch Tests of Prenotched Specimens

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Yangyan Zheng ◽  
Xiao Chen ◽  
Zheng Yang ◽  
Xiang Ling
Keyword(s):  
Fracture Toughness ◽  
Numerical Simulations ◽  
Stress Gradient ◽  
Element Model ◽  
Bending Test ◽  
J Integral ◽  
Notched Specimen ◽  
Small Punch ◽  
Three Point Bending ◽  
The Difference

In this paper, line- and ring-notched small punch test (SPT) specimens were studied; a three-dimensional (3D) model of a ring-notched SPT specimen was established using the contour integral method, and the validity of the model was verified using ring-notched specimens. The stress and strain fields were analyzed using numerical simulations of a ring-notched SPT specimen, and the change in the stress gradient during deformation was considered. To verify the finite element model, the results of the numerical simulations were compared with those of three-point bending tests and a Gurson–Tvergaard–Needleman (GTN) model. Compared with the line-notched specimen, the ring-notched specimen was more suitable for notch propagation analysis and fracture toughness evaluation. The results of the numerical simulations were in good agreement with those of the experiments, which showed that the numerical model used in this study was correct. For a notch that initiated when the load reached its maximum value, the value of the J integral was 335 × 10−6 kJ/mm2, and at time 0.85Pmax, the value of the J integral was 201 × 10−6 kJ/mm2, and the difference from the result of the three-point bending test was 14.4%. For a notch that initiated during the stretching deformation stage, the relevant fracture toughness was 225 × 10−6 kJ/mm2, and the difference from the result of the three-point bending test was 3%.

Study on the Numerical Modeling of the SRHPC Frame

2010 ◽  
Vol 163-167 ◽  
pp. 1561-1564
Author(s):  
Pi Ji Hou ◽  
Shan Suo Zheng ◽  
Lei Li
Keyword(s):  
Finite Element ◽  
Numerical Modeling ◽  
High Performance ◽  
Applied Load ◽  
Mechanical Characteristics ◽  
High Performance Concrete ◽  
Frame Structure ◽  
Test Results ◽  
Modeling Methodology

The modeling methodology is investigated for steel reinforced high performance concrete (SRHPC) in this paper. According to the mechanical characteristics of the SRHPC members, the structural section can be divided into different zones, and the element suitable for each zone is determined. Some discussion is made for how to control finite element gridding as well as applied load. Hysteretic loops of the computation results and test results agree well with each other, indicating the accuracy and applicability of the methodology. This research may be helpful for the nonlinear finite analysis of the SRHPC frame structure.

Comparison of Different Methods for Determination of Modulus of Elasticity of Composite Reinforcement Produced from Roving

2014 ◽  
Vol 1054 ◽  
pp. 104-109 ◽  
Author(s):  
Tomáš Vlach ◽  
Lenka Laiblová ◽  
Alexandru Chira ◽  
Magdaléna Novotná ◽  
Ctislav Fiala ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
High Performance ◽  
High Performance Concrete ◽  
Traditional Approach ◽  
Tensile Modulus ◽  
Bending Test ◽  
Thin Structures ◽  
Technical Textiles ◽  
Composite Reinforcement

Currently, high performance concrete (HPC) is becoming more and more popular mainly because of its great mechanical parameters. As in the case of ordinary power concrete (OPC) it is necessary to improve the load bearing capacity with using of reinforcement. The present age calls for using of very thin structures for reasons of both environmental parameters and visual quality. Based on this fact, reinforcement start to use durable composite materials, such as technical textiles made of them. Element of HPC with this type of reinforcement is called textile reinforced high performance concrete (TRHPC). It is impossible to use the traditional approach for usually used steel reinforcement if we want to design these extra-thin structures. Modeled structures are very sensitive for input parameters and the development of standards for TRC material lags. The present study is focused on the different method of approach for the determination of tensile modulus of composite reinforcement. Three used methods are compared with each other using numerical analysis of four point bending test of façade element for one type of used reinforcement. Curves from numerical analysis are finally compared with the curve from real experiment and based on this the final evaluation is generated.

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