Properties of magnesium oxide boards used as sheathing in exterior walls

Stefanie Wøhler Nielsen, Carsten Rode, Tommy Bunch-Nielsen, Kurt Kielsgaard Hansen, Wolfgang Kunther, Bent Grelk

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    Abstract

    Sheathing boards based on magnesium oxide (MgO) became very popular in the Danish market around the year 2010. However, it was realized a few years later that they condensed humidity from ambient air. The leakage from the boards led to severe problems with corrosion of metallic components and moisture uptake and degradation of wooden members. The boards have been banned from use in the Danish market since 2015, while damage cases valuing around 370 million EUR still need to be reconciled [1]. The binder in MgO board is formed by a chemical reaction between MgO and MgCl2. However, MgSO4 is a possible alternative to MgCl2, and such boards may have smaller moisture uptake, to reduce this issue. This paper gives an account of recent activities to compare properties of MgO boards, based on chlorides or sulphates. The investigations comprise: (1) Analysis of elemental composition and crystalline components, (2) Examination in optical microscope and scanning electron microscope, (3) Determination of moisture retention and water vapour permeability, (4) Analysis of chemical composition of leaked salt water from boards, and (5) Visual observation of decomposition and determination of dry mass change after exposure to high humidity.
    Original languageEnglish
    Article number02091
    JournalMATEC Web of Conferences
    Volume282
    Number of pages6
    ISSN2261-236X
    DOIs
    Publication statusPublished - 2019
    Event4th Central European Symposium on Building Physics - Prague, Czech Republic
    Duration: 2 Sept 20195 Sept 2019
    Conference number: 4
    https://www.cesbp2019.org/

    Conference

    Conference4th Central European Symposium on Building Physics
    Number4
    Country/TerritoryCzech Republic
    CityPrague
    Period02/09/201905/09/2019
    Internet address

    Bibliographical note

    This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/)

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