Role of thresholding to determine size of interfacial transition zone

P. A.Muhammed Basheer, Lulu Basheer, David Lange, Adrian Long

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Concrete may be considered a three phase material, consisting of cement matrix, aggregate and the interfacial transition zone (ITZ). The ITZ is studied usually by collecting backscattered electron (BSE) images of polished samples of concrete and by carrying out a quantitative analysis of these images. This technique makes use of the contrast between pores and cement hydrates to analyse the microstructure. Once the images are collected, grey level thresholding is used to segment regions associated with capillary porosity. The size of the ITZ is determined using this data. Different techniques have been suggested to minimise errors introduced at this stage of the analysis. The authors have carried out an investigation on 17 different concrete mixtures in an attempt to assess the role of threshold values on the size of the ITZ. The analysis was carried out using different threshold values and the thickness of the ITZ was determined for each of these values. The results indicated that the size of the transition zone is not affected by the range of threshold values used. However, the porosity of both the ITZ and the bulk cement paste varied with different threshold values. The paper proposes a method which can be used to determine a reliable threshold value.

Original languageEnglish (US)
Title of host publicationHigh-Performance Concrete
EditorsH.G. Russell
PublisherAmerican Concrete Institute
Number of pages22
ISBN (Electronic)9780870316883
StatePublished - Jan 1 2000
EventHigh-Performance Concrete Research to Practice 1999 - Chicago, United States
Duration: Mar 14 1999Mar 19 1999

Publication series

NameAmerican Concrete Institute, ACI Special Publication
ISSN (Print)0193-2527


ConferenceHigh-Performance Concrete Research to Practice 1999
Country/TerritoryUnited States


  • Aggregates
  • Cement matrix
  • Image analysis
  • Microstructure

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Materials Science(all)


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