Petrography of Historic Mortar Materials: Polarising Light Microscopy as a Method for Characterising Lime-Based Mortars

Author(s): Kristin Balksten,Bo Nitz, John J. Hughes,Jan-Erik Lindqvist
Paper category: Proceedings
Book title: Proceedings of the 5th Historic Mortars Conference
Editor(s): José Ignacio Álvarez, José María Fernández, Íńigo Navarro, Adrián Durán, Rafael Sirera
ISBN: 978-2-35158-221-3
e-ISBN: 978-2-35158-222-0
Publisher: RILEM Publications SARL
Publication year: 2019
Pages: 453-467
Total Pages: 15
Language : English

Abstract: In studying historic, repair and restoration mortars comprised of lime-based material there is
an analytical method that answers more questions than any other; transmitted (and
reflected) polarised light microscopy (PLM). The present study is based on thin-section
analysis of historic and restoration mortars made by the authors in Sweden and Scotland
since the 1980’s, previous research [1, 2, 3, 4] and petrographic atlases [5, 6, 7, 8]. This paper
is written to be a pedagogically useful complement to previous work.
We present a selection of microphotographs to show the variety of questions that the
method can give answers to, such as, in the study of:
- lime binder; source materials, hydraulicity, slaking methods, lime lumps, cracking
- aggregates; grading, mineralogy/lithology and texture
- additives; inorganic puzzolanic materials and organic materials
- paint layers; different binders, pigments, thicknesses
- pore structure; durability, vapour transport and capillarity
- craftsmanship; various application and working techniques
The aim of this paper is to contribute with more illustrations of reference materials and to
illustrate the usefulness of Polarising Light Microscopy as a method for characterising lime-
based mortars and to review the most significant analyses parameters.

Online publication : 2019
Publication type : full_text
Public price (Euros) : 0.00

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