Evaluation of physical and mechanical properties of fired-clay bricks incorporating both mineral and organic wastes

Abstract

The clay brick is one of the oldest building materials, and as the use of waste in the bricks can reduce clay consummation and the environmental burden due to the accumulation of waste, the present study was chosen, the addition of mineral and organic waste to the clay brick. The added value of this work, which was carried out within the Institute of Building Materials at VGTU, is that the mixture studied is very special, because the raw materials used are: − Yellow Clay (C) from Fez which is used only in the field of pottery; − Pyrrhotite Ash (PA) which is a mineral waste produced during the manufacture of sulphuric acid from the roasting of pyrrhotite ore. This waste is stored in the open air since 1982 and until now it doesn't have any specific use; − Cedar Sawdust (S) is an organic waste regenerate by the artisanal sector from Fez. The bricks’ technological properties depended on the amount of ashes used. So, adding 5% S to the mixture (20% PA – 80% C) gives rise to a new material that is light, porous with a natural brick red colour. Most importantly, this material exhibits mechanical strength according to the standards of a terracotta brick.

Towards the Use of Yellow Clay in Fired Bricks

“…The flexural strength decreases for bricks containing more than 30 wt.% of waste. This behavior was attributed in our previous work [20] to the firing temperature that should be higher than 1000°C, as well as the complex mineralogical transformations, occurring during the firing and cooling process, that depend on the content of Fe 2 O 3 and fluxing oxides.…”

“…Among the ash waste category, there is another industrial waste, rich in hematite Fe 2 O 3 , which is the pyrrhotite ash. Few studies were carried out for this waste to explore areas of its recovery in industry [18][19][20][21][22]. It was generated between 1964 and 1982 [1] by the sulfuric acid manufacturing process from the combustion of pyrrhotite ore extracted from the Kettara mine in Marrakech (Morocco).…”