A Statistical Theory of Time-Dependent Fracture for Cementitious Materials

1990 ◽  
pp. 37-46
Author(s):  
Xiao-Zhi Hu ◽  
Yiu-Wing Mai ◽  
Brian Cotterell
Keyword(s):  
Statistical Theory ◽  
Cementitious Materials ◽  
Time Dependent

A statistical theory of time-dependent fracture for cementitious materials subjected to cyclic loading

1989 ◽  
Vol 24 (9) ◽  
pp. 3118-3122 ◽  
Author(s):  
Xiaozhi Hu ◽  
Yiu-Wing Mai ◽  
Brian Cotterell
Keyword(s):  
Statistical Theory ◽  
Cyclic Loading ◽  
Cementitious Materials ◽  
Time Dependent

A Consistent Approach for the Development of a Comprehensive Data Base of Time-Dependent Parameters for Concrete Engineered Barriers

2013 ◽  
Author(s):  
Suresh C. Seetharam ◽  
Dirk Mallants ◽  
Janez Perko ◽  
Diederik Jacques
Keyword(s):  
Data Base ◽  
Experimental Studies ◽  
Cementitious Materials ◽  
Time Dependent ◽  
Extensive Literature ◽  
Near Surface ◽  
Comprehensive Data ◽  
Engineered Barriers ◽  
Parameter Values ◽  
Consistent Approach

This paper presents a consistent approach for the development of a comprehensive data base of time-dependent hydraulic and transport parameters for concrete engineered barriers of the future Dessel near surface repository for low level waste. The parameter derivation is based on integration of selected data obtained through an extensive literature review, data from experimental studies on cementitious materials specific for the Dessel repository and numerical modelling using physically-based models of water and mass transport. Best estimate parameter values for assessment calculations are derived, together with source and expert range and their probability density function wherever the data was sufficient. We further discuss a numerical method for upscaling laboratory derived parameter values to the repository scale; the resulting large-scale effective parameters are commensurate with numerical grids used in models for radionuclide migration. To accommodate different levels of conservatism in the various assessment calculations defined by ONDRAF/NIRAS, several sets of parameter values have been derived based on assumptions that introduce different degrees of conservatism. For pertinent parameters, the time evolution of such properties due to the long-term concrete degradation is also addressed. The implementation of the consistent approach is demonstrated by considering the pore water diffusion coefficient as an example.

A numerical model for the time‐dependent cracking of cementitious materials

2001 ◽  
Vol 52 (7) ◽  
pp. 637-654 ◽  
Author(s):  
G. P. A. G. van Zijl ◽  
R. de Borst ◽  
J. G. Rots
Keyword(s):  
Numerical Model ◽  
Cementitious Materials ◽  
Time Dependent

scholarly journals Trends in Block-Seasonal Extreme Rainfall over the Iberian Peninsula in the Second Half of the Twentieth Century

2007 ◽  
Vol 20 (1) ◽  
pp. 113-130 ◽  
Author(s):  
JoséAgustín García ◽  
María Cruz Gallego ◽  
Antonio Serrano ◽  
JoséManuel Vaquero
Keyword(s):  
Twentieth Century ◽  
Statistical Theory ◽  
Iberian Peninsula ◽  
Extreme Values ◽  
Extreme Rainfall ◽  
Kendall Test ◽  
Time Dependent ◽  
The West ◽  
Daily Scale ◽  
Dipolar Pattern

Abstract In this study trends in extreme rainfall over the Iberian Peninsula at a daily scale in the second half of the twentieth century have been detected and analyzed. For this goal 35 stations evenly distributed over the region of study covering the period 1958–97 have been studied. Two different approaches have been used. The first one consists of the nonparametric Mann–Kendall test and the Sen method. The second approach is based on the statistical theory of extreme values, involving time-dependent parameters in order to be able to reflect possible temporal changes in the frequency distribution. Results from both methods agree, confirming the reliability of the analysis. Negative trends are found for the west and southwest of the Iberian Peninsula in spring and winter. In autumn a spatial dipolar pattern appears, but trends are not so evident.

scholarly journals Variation of Durability and Strength Parameters of Pumice Based Mixtures

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3674
Author(s):  
Petr Lehner ◽  
Petr Konečný ◽  
Pratanu Ghosh
Keyword(s):  
Diffusion Coefficient ◽  
Portland Cement ◽  
Mean Squared Error ◽  
High Performance Concrete ◽  
Limit State ◽  
Cementitious Materials ◽  
Time Dependent ◽  
Supplementary Cementitious Materials ◽  
Ultimate Limit State ◽  
Concrete Mixtures

The numerical modelling of chloride penetration into concrete is very sensitive to the correct description of the input data. In the recent era, high-performance concrete (HPC), which combines Portland cement and other supplementary cementitious materials, has been gaining attraction due to their desirable material properties and durability. The presented results show the application of the modified approach for the evaluation of the suitability of the time-dependent model for the variation of the diffusion coefficient. The 26 various binary and ternary-based concrete mixtures blended with volcanic pumice pozzolan (VPP) as a major supplementary cementitious material (SCM) are compared with the reference Ordinary Portland Cement mixture. Other SCMs namely fly ash, slag, silica fume, and metakaolin were also utilized in ternary-based concrete mixtures. In-depth statistical analysis was carried out to show the variability and effects of the amount of the volcanic pumice as an SCM on the diffusion coefficient. The mean value and regression via linear approximation of the time-dependent coefficient of variation of the diffusion coefficients were used as well as the Root of Mean Squared Error approach. The presented results are suitable as the component of the input parameters for the durability-related probabilistic assessment of the reinforced concrete structures exposed to chlorides. In addition, the time-dependent ultimate limit state-related data was presented.

Microstructural Aspects of Stress Corrosion of Cementitious Materials

1986 ◽  
Vol 85 ◽  
Author(s):  
U. Schneider ◽  
E. Nagele ◽  
N. Dujardin
Keyword(s):  
Corrosion Resistance ◽  
Flexural Strength ◽  
Stress Corrosion ◽  
Cement Mortar ◽  
Cementitious Materials ◽  
Strength Reduction ◽  
Time Dependent ◽  
Hardened Cement ◽  
Chemical Attack ◽  
Comprehensive Study

ABSTRACTStress corrosion phenomena, i.e. significant effects of mechanical stresses on the corrosion resistance of materials, have been reported for a large variety of materials, including metals, oxides and halides. Recently it has been shown [1,2] that cementitious materials are also sensitive to stress corrosion. The time dependent decrease in the flexural strength of chemically stressed concrete and mortar depends significantly on the mechanical stress acting simultaneously with the chemical attack.For cementitious materials a comprehensive study of the stress corrosion phenomena has been started. In this paper the latest results from the current research program are presented and the interrelations between the microstructure of hardened cement mortar and the strength reduction caused by stress corrosion, are briefly discussed.

scholarly journals Oscillations of Long-Period Variables

1998 ◽  
Vol 185 ◽  
pp. 399-400
Author(s):  
D.R. Xiong ◽  
L. Deng ◽  
Q. L. Cheng
Keyword(s):  
Statistical Theory ◽  
High Temperature ◽  
Instability Region ◽  
Time Dependent ◽  
Instability Strip ◽  
Long Period ◽  
Long Period Variables ◽  
Metal Abundance ◽  
Period Variable ◽  
Pulsational Stability

We have performed a linear pulsational stability survey of long period variable models. The dynamic and thermodynamic couplings between convection and oscillations are treated by using a statistical theory of nonlocal and time-dependent convection. The results show that the fundamental and all the low overtones are always pulsationally unstable for the low-temperature models when the coupling between convection and oscillations is ignored. When the coupling is considered, there is indeed a “Mira” pulsationally instability region outside of the Cepheid instability strip on the H-R diagram. The coolest models near the Hayashi track are pulsationally stable. Towards high temperature the fundamental mode first becomes unstable, and then the first overtone. Some of the 2nd −4th overtones may become unstable for the hotter models. All the modes higher than 4th (n > 4) are pulsationally stable. The position and the width of such an instability region on the H-R diagram critically depends on the mass, luminosity and metal abundance of the star.

A statistical theory of time-dependent fracture for brittle materials

1988 ◽  
Vol 58 (2) ◽  
pp. 299-324 ◽  
Author(s):  
Xiao-Zhi Hu ◽  
Yiu-Wing Mai ◽  
Brian Cotterell
Keyword(s):  
Statistical Theory ◽  
Brittle Materials ◽  
Time Dependent
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