A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Pilot Field Survey of Maryland Bridges for Delayed Ettringite Formation Damage. Volume I
The study investigated the possible presence of Delayed Ettringite Formation (DEF) in the Maryland Bridge Inventory. The objective of the study included investigating the possible presence of DEF in cast-in-place concrete. Two nondestructive test (NDT) methods, potassium autoradiography and impact-echo, were utilized in the study. In addition, cores were taken for analysis with a scanning electron microscope and energy dispersive analysis x-ray, which identify DEF by crystal morphology and elemental composition. The focus of this study was on bridges exhibiting wet map cracking on the surface, which is regarded as a surrogate for DEF. The PONTIS Bridge Management System provided a means for selecting a sampling population. In order to reduce the total population to the 'sick' population, the PONTIS database was queried for concrete element with descriptions containing the phrase 'map cracks'. A representative number of bridges from this set were selected from each district based on the percentage of total bridges in that district. The study found DEF throughout the sampled Maryland bridges indicating that DEF is not simply a regional problem that affects only a few states like Texas. Of the twenty-nine cores taken, twenty-six exhibited DEF and two bridges without visible map cracking also contained DEF. Alkali-silica reaction (ASR) gel, which is commonly said to be associated with map cracking, was observed in only a limited number of bridges with map cracking. Therefore, map cracking is not necessarily a definitive indicator of ASR. The study also showed cases of coexistence of DEF and ASR in six of the ten bridges cored, with this sample population showing a correlation between a distinct map cracking pattern on the exterior surface and DEF/ASR within the concrete.
Pilot Field Survey of Maryland Bridges for Delayed Ettringite Formation Damage. Volume I
The study investigated the possible presence of Delayed Ettringite Formation (DEF) in the Maryland Bridge Inventory. The objective of the study included investigating the possible presence of DEF in cast-in-place concrete. Two nondestructive test (NDT) methods, potassium autoradiography and impact-echo, were utilized in the study. In addition, cores were taken for analysis with a scanning electron microscope and energy dispersive analysis x-ray, which identify DEF by crystal morphology and elemental composition. The focus of this study was on bridges exhibiting wet map cracking on the surface, which is regarded as a surrogate for DEF. The PONTIS Bridge Management System provided a means for selecting a sampling population. In order to reduce the total population to the 'sick' population, the PONTIS database was queried for concrete element with descriptions containing the phrase 'map cracks'. A representative number of bridges from this set were selected from each district based on the percentage of total bridges in that district. The study found DEF throughout the sampled Maryland bridges indicating that DEF is not simply a regional problem that affects only a few states like Texas. Of the twenty-nine cores taken, twenty-six exhibited DEF and two bridges without visible map cracking also contained DEF. Alkali-silica reaction (ASR) gel, which is commonly said to be associated with map cracking, was observed in only a limited number of bridges with map cracking. Therefore, map cracking is not necessarily a definitive indicator of ASR. The study also showed cases of coexistence of DEF and ASR in six of the ten bridges cored, with this sample population showing a correlation between a distinct map cracking pattern on the exterior surface and DEF/ASR within the concrete.
Pilot Field Survey of Maryland Bridges for Delayed Ettringite Formation Damage. Volume I
A. M. Mende (author) / M. Ceary (author) / R. A. Livingston (author) / N. McMorris (author)
2004
203 pages
Report
No indication
English
| British Library Conference Proceedings | 2006
| Online Contents | 2001
| Tema Archive | 2001
Concrete Damage Induced by Delayed Ettringite Formation
| British Library Conference Proceedings | 2000
| British Library Online Contents | 2001