Documents disponibles écrits par cet auteur

Characterising the time-dependant behaviour on the single fibre level of SHCC: Part 2: The rate effects on fibre pull-out tests / William P. Boshoff in Cement and concrete research, Vol. 39 N° 9 (Septembre 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 9 (Septembre 2009) . - pp. 787–797 Titre : Characterising the time-dependant behaviour on the single fibre level of SHCC: Part 2: The rate effects on fibre pull-out tests Type de document : texte imprimé Auteurs : William P. Boshoff, Auteur ; Viktor Mechtcherine, Auteur ; Van Zijl, Gideon P. A., Auteur Année de publication : 2009 Article en page(s) : pp. 787–797 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Fibre  reinforcement;  Pull-out  strength;  Tensile  properties;  Rate  effects;  SHCC Résumé : This paper is the second part of a two paper series about the time-dependant behaviour of Strain Hardening Cement-based Composite (SHCC) on the single fibre level. Having dealt with mechanisms of creep in SHCC in the first part, this paper reports single fibre pull-out tests that were done to investigate the effect of the pull-out rate on the mechanical response of the interface between the fibre and the matrix. It was found that not only the pull-out resistance increased with an increase of the pull-out rate but the probability of fibre rupture during pull-out as well. Another important finding was that the interfacial shear resistance and slip-hardening coefficient are not only dependant on the pull-out rate, but also the embedment length. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001355 [article] Characterising the time-dependant behaviour on the single fibre level of SHCC: Part 2: The rate effects on fibre pull-out tests [texte imprimé] / William P. Boshoff, Auteur ; Viktor Mechtcherine, Auteur ; Van Zijl, Gideon P. A., Auteur . - 2009 . - pp. 787–797. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 9 (Septembre 2009) . - pp. 787–797 Mots-clés : Fibre  reinforcement;  Pull-out  strength;  Tensile  properties;  Rate  effects;  SHCC Résumé : This paper is the second part of a two paper series about the time-dependant behaviour of Strain Hardening Cement-based Composite (SHCC) on the single fibre level. Having dealt with mechanisms of creep in SHCC in the first part, this paper reports single fibre pull-out tests that were done to investigate the effect of the pull-out rate on the mechanical response of the interface between the fibre and the matrix. It was found that not only the pull-out resistance increased with an increase of the pull-out rate but the probability of fibre rupture during pull-out as well. Another important finding was that the interfacial shear resistance and slip-hardening coefficient are not only dependant on the pull-out rate, but also the embedment length. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001355

Charactéristing the time-dependant behaviour on the single fibre level of SHCC / William P. Boshoff in Cement and concrete research, Vol. 39 N° 9 (Septembre 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 9 (Septembre 2009) . - pp. 779–786 Titre : Charactéristing the time-dependant behaviour on the single fibre level of SHCC : Part 1: mechanism of fibre pull-out creep Type de document : texte imprimé Auteurs : William P. Boshoff, Auteur ; Viktor Mechtcherine, Auteur ; Van Zijl, Gideon P. A., Auteur Année de publication : 2009 Article en page(s) : pp. 779–786 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Creep;  Fibre  reinforcement;  Tensile  properties;  Shrinkage;  Fibre  pull-out Résumé : SHCC (Strain Hardening Cement-based Composite) has been designed and optimised to overcome the main weaknesses of ordinary concrete, which is its brittleness. SHCC shows a high tensile ductility and can resist the full load at a tensile strain of more than 4%. An in depth investigation into the time-dependant behaviour is still lacking for SHCC. This paper is the first part of a two paper series about the time-dependant behaviour on the single fibre level. In this paper, the tensile creep behaviour of SHCC is studied to distinguish mechanisms of creep. Tensile creep and shrinkage test results are reported for dumbbell type SHCC specimens. The specimens are pre-cracked to simulate in-service conditions, with subsequent sustained load at various levels, here chosen as 30%, 50%, 70% and 80% of the ultimate resistance. To distinguish the sources of significant creep deformation under these sustained loads, single fibre pull-out tests are performed under sustained load. It is shown that the time-dependent fibre pull-out is a significant source of time-dependent deformation, along with the formation of new cracks in SHCC under sustained load. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001379 [article] Charactéristing the time-dependant behaviour on the single fibre level of SHCC : Part 1: mechanism of fibre pull-out creep [texte imprimé] / William P. Boshoff, Auteur ; Viktor Mechtcherine, Auteur ; Van Zijl, Gideon P. A., Auteur . - 2009 . - pp. 779–786. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 9 (Septembre 2009) . - pp. 779–786 Mots-clés : Creep;  Fibre  reinforcement;  Tensile  properties;  Shrinkage;  Fibre  pull-out Résumé : SHCC (Strain Hardening Cement-based Composite) has been designed and optimised to overcome the main weaknesses of ordinary concrete, which is its brittleness. SHCC shows a high tensile ductility and can resist the full load at a tensile strain of more than 4%. An in depth investigation into the time-dependant behaviour is still lacking for SHCC. This paper is the first part of a two paper series about the time-dependant behaviour on the single fibre level. In this paper, the tensile creep behaviour of SHCC is studied to distinguish mechanisms of creep. Tensile creep and shrinkage test results are reported for dumbbell type SHCC specimens. The specimens are pre-cracked to simulate in-service conditions, with subsequent sustained load at various levels, here chosen as 30%, 50%, 70% and 80% of the ultimate resistance. To distinguish the sources of significant creep deformation under these sustained loads, single fibre pull-out tests are performed under sustained load. It is shown that the time-dependent fibre pull-out is a significant source of time-dependent deformation, along with the formation of new cracks in SHCC under sustained load. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001379

Fracture mechanical behavior of concrete and the condition of its fracture surface / Viktor Mechtcherine in Cement and concrete research, Vol. 39 N° 7 (Juillet 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 7 (Juillet 2009) . - pp. 620–628 Titre : Fracture mechanical behavior of concrete and the condition of its fracture surface Type de document : texte imprimé Auteurs : Viktor Mechtcherine, Auteur Année de publication : 2009 Article en page(s) : pp. 620–628 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Concrete;  Heterogeneity;  Fracture  mechanics;Stress–crack  pening  relations;  Fracture  surfaces;  Fractal  geometry Résumé : In this research project, a series of uniaxial, deformation controlled tensile tests were performed in order to study the fracture mechanical behavior of concrete. The parameters under investigation were the strength of concrete, curing conditions, concrete temperature and loading rate. The fracture surfaces of the tested specimens were investigated in detail and their condition was quantified using the fractal geometry. The evaluation of the experimental results and the results of the fractological investigation displayed correlations between the shape of the stress–crack opening relation of concrete and the values of the roughness as well as the fractal dimension of its fracture surface for all parameters under investigation. Relationships were drawn between the individual material as well as test parameters and the degree of concrete heterogeneity, which proved to be decisive for the formation and propagation of cracks in concrete. It was concluded that the roughness of the fracture surfaces might be considered as a representative replica of the crack system correlating directly with the concrete heterogeneity. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000726 [article] Fracture mechanical behavior of concrete and the condition of its fracture surface [texte imprimé] / Viktor Mechtcherine, Auteur . - 2009 . - pp. 620–628. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 7 (Juillet 2009) . - pp. 620–628 Mots-clés : Concrete;  Heterogeneity;  Fracture  mechanics;Stress–crack  pening  relations;  Fracture  surfaces;  Fractal  geometry Résumé : In this research project, a series of uniaxial, deformation controlled tensile tests were performed in order to study the fracture mechanical behavior of concrete. The parameters under investigation were the strength of concrete, curing conditions, concrete temperature and loading rate. The fracture surfaces of the tested specimens were investigated in detail and their condition was quantified using the fractal geometry. The evaluation of the experimental results and the results of the fractological investigation displayed correlations between the shape of the stress–crack opening relation of concrete and the values of the roughness as well as the fractal dimension of its fracture surface for all parameters under investigation. Relationships were drawn between the individual material as well as test parameters and the degree of concrete heterogeneity, which proved to be decisive for the formation and propagation of cracks in concrete. It was concluded that the roughness of the fracture surfaces might be considered as a representative replica of the crack system correlating directly with the concrete heterogeneity. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000726