Using Epifluorescence Optical Microscopy to Identify Causes of Concrete Distress: Case Study

Autor:	Karl Peterson, Lawrence L. Sutter, Thomas J. Van Dam, Kurt D Smith
Rok vydání:	2002
Předmět:	Distress Portland cement Water–cement ratio Materials science Optical microscope law Mechanical Engineering Microscopy Forensic engineering Diagnostic test Civil and Structural Engineering law.invention
Zdroj:	Transportation Research Record: Journal of the Transportation Research Board. 1798:22-30
ISSN:	2169-4052 0361-1981
DOI:	10.3141/1798-04
Popis:	Materials-related distress (MRD) has affected many portland cement concrete pavements. Identifying the specific cause of MRD is not always possible, but with the use of appropriate techniques and a diagnostic approach, the cause can be determined in many cases. In a case studied as part of an FHWA project titled Detection, Analysis, and Treatment of Materials-Related Distress in Concrete Pavements, apparent MRDs were identified. In one case study, determination of the effective water-to-cement ratio (w/c) by epifluorescence microscopy was the key to understanding the cause of distress. The effective w/c, which may not be exact for a given concrete on an absolute basis, was used to compare two concrete microstructures on a relative basis. Stereo-optical microscopy, petrographic optical microscopy, and scanning electron microscopy were also used to identify the MRD diagnostic features present in the distressed concrete. As a result of this analysis, evidence of paste freeze–thaw and deicer attack was identified, but the principal cause of the distress probably was a high w/c in the distressed concrete.
Databáze:	OpenAIRE
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