4. Conclusions
This study evaluated the possibility of using wood wastes
(sawdust) as a pore forming agent for producing porcelain stoneware
ceramic tiles with novel features.
Lightweight bi-layered bodies showing suitable mechanical
resistance and low thermal conductivity were fabricated, attesting
to the potential of using sawdust as a pore forming agent in such
fast-fired ceramic products.
Optical microscopy and mercury intrusion porosimetry characterization
demonstrated that the porosity level is controlled by
sawdust content, and therefore can be tuned considering the
application envisaged.
Sawdust presents fast and complete combustion, without leaving
residues or ashes, and does not induce defects in the ceramics
bodies. Additionally, the heat released from its decomposition
brings value to the ceramic tile manufacturing process, allowing
energy savings.
The incorporation of sawdust in the bottom layer of the bilayered
ceramics promotes weight reduction (up to 7.5%) and
simultaneous thermal conductivity attenuation (up to 76%). The
low porogen percolation threshold (5 wt%) achieved endorsed a
threefold decrease in the ceramic tile's thermal conductivity in
comparison to commercial stoneware tiles. At the same time, the
product complies with mechanical strength requirements when
sawdust incorporation level is below 10 wt%.
Results demonstrate that innovative products with excellent
features can be produced by incorporation of sawdust into porcelain
stoneware ceramic tiles. The novel ceramic tiles ensure environmental,
technical and economic advantages: waste valorisation
by sawdust reuse (environmental advantage); density reduction of
the product which decreases the tiles transportation and distribution
costs (economic advantage); restrain energy loss (technical
advantage). These new and exciting features may widen the range
of applications of porcelain stoneware tiles while simultaneously
contributing towards sustainable construction.