Analysis of the porous structure of fired ceramic pieces: influence of sawdust addition on various particle sizes.

Abstract

The aim of this study was to evaluate the effect of incorporating pine sawdust as a pore-forming agent into clay-based compositions intended for the production of structural ceramic materials, analyzing its influence on the physical, mechanical, and microstructural properties of the resulting products. The specimens were formed by uniaxial pressing at 25 MPa using clay–sawdust mixtures containing 2 wt.% biomass, with different particle-size fractions (< 0.044 mm, 0.250–0.500 mm, and 1–2 mm). The formulations were conditioned to a moisture content of 8% and molded in 70 × 40 mm dies, yielding samples approximately 15 mm thick. Subsequently, the specimens were subjected to thermal treatment at 1000 °C for 3 h.
The sintered ceramic materials exhibited a homogeneous reddish coloration, adequate structural cohesion, and no significant surface defects, such as cracking, exfoliation, or granular spalling, demonstrating good dimensional stability during firing.
The experimental results indicated that all compositions presented comparable physical and mechanical properties that were consistent with the regulatory requirements for their application and commercialization. Furthermore, it was observed that the morphology of the pores developed during firing retained similarities to the original geometry of the biomass particles used, although with reduced dimensions. Additionally, the pore size generated was found to correspond to approximately 60–70% of the initial size of the sawdust particles, demonstrating the possibility of tailoring the porous microstructure of ceramic materials through the controlled incorporation of residual biomass as a pore-forming agent.