Microstructural and statistical evaluation of interfacial zone percolation in concrete

• Published in: Strength, fracture and complexity Vol. 3; no. 2-4; pp. 191 - 197
• Main Authors: Nemati, Kamran M., Gardoni, Paolo
• Format: Journal Article Conference Proceeding
• Language: English
• Published: London, England SAGE Publications 01.05.2005; IOS Press
• Subjects: Applied sciences; Exact sciences and technology; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Metals. Metallurgy; Physics; Polymer industry, paints, wood; Solid mechanics; Structural and continuum mechanics; Wood; Wood. Paper. Non wovens; concrete; scanning electron microscopy; backscattered electron imaging; aleatory; epistemic; microstructure; porosity; Cement; image analysis; interfacial transition zone; uncertainties; Interfacial layer; Transport properties; Image processing; Backscattering; Modeling; Liquid metal; Uncertain system; Cavity; Percolation; Scanning electron microscopy; Statistical analysis; Probabilistic approach; Wood; Paste; Rupture; Experimental study; Image analysis; Concrete construction; Concrete; Porosity; Aggregate; Microstructure
• ISSN: 1567-2069; 1875-9262
• DOI: 10.3233/SFC-2005-058

In freshly compacted concrete, water films form around aggregate particles, which results in a higher water/cement ratio closer to the aggregate than away from it. The interface between cement paste and aggregate, known as interfacial transition zone (ITZ), has a significantly higher porosity than bulk cement paste. This higher porosity in ITZ affects the transport properties of concrete. The Wood's metal technique was used to intrude molten metal alloy into voids and fractures in concrete which was then solidified to preserve the microstructure. The penetration of this alloy into concrete samples indicates that the porosity in the interfacial zone is permeated preferentially to the bulk paste. This technique also indicates the width of the interfacial zone in which the porosity is interconnected. The results of this experimental study were evaluated in a probabilistic sense and subject to statistical considerations. In particular, the results and interpretations of this study properly account for the aleatory and epistemic uncertainties inherent in the data.