Documents disponibles écrits par cet auteur

Measuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting / Nicolas Robeyst in Cement and concrete research, Vol. 39 N° 10 (Octobre 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 10 (Octobre 2009) . - pp. 868–875 Titre : Measuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting Type de document : texte imprimé Auteurs : Nicolas Robeyst, Auteur ; Christian U. Grosse, Auteur ; Nele de Belie, Auteur Année de publication : 2009 Article en page(s) : pp. 868–875 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Ultrasonic;  Fresh  concrete  (A);  Granulated  blast-furnace  slag  (D);  Fly  ash  (D);  Admixture  (D) Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Research on ultrasonic methods to monitor the setting of concrete has mainly focussed on the wave velocity as a useful quantity. To investigate the application of also the wave energy as a parameter, an experimental program was set up to apply the ultrasonic wave transmission technique on several mortar samples containing air entrainer, blast-furnace slag or fly ash causing clearly different setting behaviour. The increase of the relative energy E/Eref during setting is generally retarded if ordinary Portland cement is replaced by blast-furnace slag or fly ash. The mixtures with cement of a lower strength class or with large air content were difficult to test with the energy measurements since they were more sensitive to poor sensor contact due to shrinkage. For the other samples, the thresholds E/Eref = 0.02 and 0.13 are proposed to easily determine respectively initial and final setting based on the ultrasonic energy measurements. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001471 [article] Measuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting [texte imprimé] / Nicolas Robeyst, Auteur ; Christian U. Grosse, Auteur ; Nele de Belie, Auteur . - 2009 . - pp. 868–875. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 10 (Octobre 2009) . - pp. 868–875 Mots-clés : Ultrasonic;  Fresh  concrete  (A);  Granulated  blast-furnace  slag  (D);  Fly  ash  (D);  Admixture  (D) Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Research on ultrasonic methods to monitor the setting of concrete has mainly focussed on the wave velocity as a useful quantity. To investigate the application of also the wave energy as a parameter, an experimental program was set up to apply the ultrasonic wave transmission technique on several mortar samples containing air entrainer, blast-furnace slag or fly ash causing clearly different setting behaviour. The increase of the relative energy E/Eref during setting is generally retarded if ordinary Portland cement is replaced by blast-furnace slag or fly ash. The mixtures with cement of a lower strength class or with large air content were difficult to test with the energy measurements since they were more sensitive to poor sensor contact due to shrinkage. For the other samples, the thresholds E/Eref = 0.02 and 0.13 are proposed to easily determine respectively initial and final setting based on the ultrasonic energy measurements. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001471

Measuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting / Nicolas Robeyst in Cement and concrete research, Vol. 39 N° 10 (Octobre 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 10 (Octobre 2009) . - pp. 868–875 Titre : Measuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting Type de document : texte imprimé Auteurs : Nicolas Robeyst, Auteur ; Christian U. Grosse, Auteur ; Nele de Belie, Auteur Année de publication : 2009 Article en page(s) : pp. 868–875 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Ultrasonic;  Fresh  concrete  (A);  Granulated  blast-furnace  slag  (D);  Fly  ash  (D);  Admixture  (D) Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Research on ultrasonic methods to monitor the setting of concrete has mainly focussed on the wave velocity as a useful quantity. To investigate the application of also the wave energy as a parameter, an experimental program was set up to apply the ultrasonic wave transmission technique on several mortar samples containing air entrainer, blast-furnace slag or fly ash causing clearly different setting behaviour. The increase of the relative energy E/Eref during setting is generally retarded if ordinary Portland cement is replaced by blast-furnace slag or fly ash. The mixtures with cement of a lower strength class or with large air content were difficult to test with the energy measurements since they were more sensitive to poor sensor contact due to shrinkage. For the other samples, the thresholds E/Eref = 0.02 and 0.13 are proposed to easily determine respectively initial and final setting based on the ultrasonic energy measurements. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001471 [article] Measuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting [texte imprimé] / Nicolas Robeyst, Auteur ; Christian U. Grosse, Auteur ; Nele de Belie, Auteur . - 2009 . - pp. 868–875. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 10 (Octobre 2009) . - pp. 868–875 Mots-clés : Ultrasonic;  Fresh  concrete  (A);  Granulated  blast-furnace  slag  (D);  Fly  ash  (D);  Admixture  (D) Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Research on ultrasonic methods to monitor the setting of concrete has mainly focussed on the wave velocity as a useful quantity. To investigate the application of also the wave energy as a parameter, an experimental program was set up to apply the ultrasonic wave transmission technique on several mortar samples containing air entrainer, blast-furnace slag or fly ash causing clearly different setting behaviour. The increase of the relative energy E/Eref during setting is generally retarded if ordinary Portland cement is replaced by blast-furnace slag or fly ash. The mixtures with cement of a lower strength class or with large air content were difficult to test with the energy measurements since they were more sensitive to poor sensor contact due to shrinkage. For the other samples, the thresholds E/Eref = 0.02 and 0.13 are proposed to easily determine respectively initial and final setting based on the ultrasonic energy measurements. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001471

Use of bacteria to repair cracks in concrete / Kim Van Tittelboom in Cement and concrete research, Vol. 40 N° 1 (Janvier 2010) 

Public ISBD [article]  in Cement and concrete research > Vol. 40 N° 1 (Janvier 2010) . - pp. 157-166 Titre : Use of bacteria to repair cracks in concrete Type de document : texte imprimé Auteurs : Kim Van Tittelboom, Auteur ; Nele de Belie, Auteur ; Willem de Muynck, Auteur Article en page(s) : pp. 157-166 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Concrete  Microcracking  CaCO3  Bacteria Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : As synthetic polymers, currently used for concrete repair, may be harmful to the environment, the use of a biological repair technique is investigated in this study. Ureolytic bacteria such as Bacillus sphaericus are able to precipitate CaCO3 in their micro-environment by conversion of urea into ammonium and carbonate. The bacterial degradation of urea locally increases the pH and promotes the microbial deposition of carbonate as calcium carbonate in a calcium rich environment. These precipitated crystals can thus fill the cracks. The crack healing potential of bacteria and traditional repair techniques are compared in this research by means of water permeability tests, ultrasound transmission measurements and visual examination. Thermogravimetric analysis showed that bacteria were able to precipitate CaCO3 crystals inside the cracks. It was seen that pure bacteria cultures were not able to bridge the cracks. However, when bacteria were protected in silica gel, cracks were filled completely. DEWEY : 627 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235562%23 [...] [article] Use of bacteria to repair cracks in concrete [texte imprimé] / Kim Van Tittelboom, Auteur ; Nele de Belie, Auteur ; Willem de Muynck, Auteur . - pp. 157-166. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 40 N° 1 (Janvier 2010) . - pp. 157-166 Mots-clés : Concrete  Microcracking  CaCO3  Bacteria Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : As synthetic polymers, currently used for concrete repair, may be harmful to the environment, the use of a biological repair technique is investigated in this study. Ureolytic bacteria such as Bacillus sphaericus are able to precipitate CaCO3 in their micro-environment by conversion of urea into ammonium and carbonate. The bacterial degradation of urea locally increases the pH and promotes the microbial deposition of carbonate as calcium carbonate in a calcium rich environment. These precipitated crystals can thus fill the cracks. The crack healing potential of bacteria and traditional repair techniques are compared in this research by means of water permeability tests, ultrasound transmission measurements and visual examination. Thermogravimetric analysis showed that bacteria were able to precipitate CaCO3 crystals inside the cracks. It was seen that pure bacteria cultures were not able to bridge the cracks. However, when bacteria were protected in silica gel, cracks were filled completely. DEWEY : 627 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235562%23 [...]