Effect of chromated copper arsenate retention on the stiffness and compressive strength of Eucalyptus grandis wood
Abstract
Wood is a material that is widely used in many applications such as construction due to its ease
of working and high strength to weight ratio. E. grandis wood is one of the most commonly used
species of wood for structural purposes in Uganda. Since wood is a natural organic material, it is
highly susceptible to decay by degrading agents. Wood preservation has been used to prevent
this deterioration and prolong the wood’s service life. CCA and creosote are the most effective
preservatives but are known to negatively affect wood in some aspects. The objective of this
study was to determine the effect of CCA retention on the stiffness and compressive strength of
wood at varying moisture contents. E. grandis wood samples at varying moisture contents were
treated using the full cell pressure treatment process. The retention and mechanical properties of
the treated wood samples were tested, recorded with untreated samples as controls. Retention of
CCA was found to decrease with an increase in the moisture content of wood. Wood with 40%
moisture content had a mean retention of 16.15 kg/m3 while air dried wood with 15% moisture
content had a mean retention of 21.44kg/m3
. Stiffness of the wood samples was found to be
reduced by CCA treatment. Untreated wood samples had a mean stiffness of 8157.9 MPa, wood
with 40% moisture content had a mean stiffness of 7293.42MPa while wood with 15% moisture
content had a mean retention of 6522.00MPa. Compression parallel to grain was found to be
reduced by CCA treatment. Untreated wood samples had a mean compression parallel to grain of
38.03 MPa, wood with 40% moisture content had a mean compression parallel to grain of 36.37
MPa while wood with 15% moisture content had a mean compression parallel to grain of 34.52
MPa. CCA treatment had no significant effect on compression perpendicular to grain of wood.
Therefore, moisture content has an effect on CCA retention in wood and treating wood with
CCA has an effect on the stiffness and compression parallel to grain while it has no effect on
compression perpendicular to grain.