Improvement of thermal properties of fired clays by introduction of vegetable matter

Porous bricks produced by extrusion were obtained by adding vegetable matter of various compositions and shapes. The main objective of this article is precisely to investigate the possibilities offered by vegetable matter. During firing, the burning of the vegetable matter created pores and an increase in open porosity ranging from 11% to 18% was obtained. The linear shrinkage and mass loss of bricks were acceptable. The mechanical properties were studied by the three-point bending method and sound wave propagation. The results obtained showed that the rigidity of the material and its thermal conductivity decreased by up to 32%, as the porosity increased. An improvement of up to 18-48% in the thermal resistance of industrial perforated bricks could be expected, depending on their nature. Porosity obtained by adding wheat straw provided the best compromise between thermal and mechanical properties.