A CertMark assisted study on MGO boards conducted by;
the a School of Science and Engineering, University of the Sunshine Coast, Maroochydore, Qld 4556, Australia; and
College of Engineering, Information Technology and Environment, Charles Darwin University, Darwin, NT 0909, Australia,
has been published by the Elsevier – Construction and Building Materials journal.
Assessing variability in the hygrothermal performance of magnesium oxide (MgO) cladding products of the Australian market
Published 19 January 2019
a b s t r a c t
Magnesium oxide (MgO) boards are relatively new cladding materials on the Australian construction
market. They are chosen primarily for their fire resisting properties and are fast replacing traditional cladding
materials in newer buildings. Recent reports of water staining on MgO boards is thought to be due to
the effects of relative humidity promoting corrosion of metallic fasteners. Different commercially available
MgO board samples were investigated by following their behaviour in a controlled relative humidity
environment and when in contact with different metallic fasteners. It is observed that water absorption is
different for different products and that staining varied with the composition of the metallic fasteners.
Staining and water absorption was not a problem at a low relative humidity (RH) of 75% but was evident
at a high humidity of 97% for all but one of the MgO board samples. The concentration of chloride is implicated
and has its origin in the binder material. These results emphasise the need for standard characterisation
of commercially available MgO boards for their use in high humidity environments.
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