SAMPLING CONCRETE BY TOO SMALL ELEMENTS; WHAT SHOULD WE DO TO GET RELIABLE INFORMATION?

Piet Stroeven, Zhanqi Guo

Abstract

Macroscopically heterogeneous materials like concrete are generally sampled by too small, i.e., subrepresentative elements that can be either of 2D (section images) or of 3D nature (specimens). Based on scientific notions, like stochastic heterogeneity and structure-sensitivity, which are at the very heart of materials science and stereology, the paper demonstrates biases in obtained information to be generally inevitable when derived from such sub-representative designs. Only reliable comparison studies can be performed under the condition that the linear size of samples and of minimum structural dimensions (resulting from observation resolution) are maintained as fixed proportions of the relevant representative area and/or volume elements. This is demonstrated by three case studies.

Keywords
concrete; representative element; stochastic heterogeneity; structure-sensitivity

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DOI: 10.5566/ias.v27.p151-162

Image Analysis & Stereology
EISSN 1854-5165 (Electronic version)
ISSN 1580-3139 (Printed version)