Light-weighing traditional ceramics by porosity control and consequences on mechanical strength

Abstract

This work evaluates the impacts of the addition of cellulose fibres (5 and 10 wt%) and pumice powder (5 wt%) as pore forming agents on the porosity, microstructure and mechanical strength of two traditional ceramic compositions: stoneware and terracotta. Open and closed porosities, pore size distribution and morphology were obtained from the combined use of the Archimedes method, mercury intrusion porosimetry and SEM image analyses.The results show an increase in the open porosity ratio in the case of cellulose fibre addition, whereas pumice powder addition promotes an increase in the closed porosity. The addition of cellulose also modifies the pore morphology of stoneware samples and induces a pore size increase. The decrease in mechanical strength caused by a lower firing temperature is greater than the decrease linked to the porosity generated by pore-forming agent addition. As the moduli of rupture of the produced porous tiles are higher than those needed by the standards, this work proposes new opportunities for lightning ceramic products.