Preliminary study of the use of spent diatomaceous earth from the brewing industry in clay matrix bricks

In this work the effect of spent diatomaceous earth (SDE), as pore forming or silica carrier, on the properties of clay ceramic bricks was investigated. Mixtures of clay and SDE waste were, compacted, dried and fired at 950°C during 6 h. The technological properties of waste-clay bricks were analysed to evaluate the influence of the waste incorporation. The SDE (1–5 wt-%) addition in the clay matrix causes a reduction between 6 and 12% of the bulk density compared with the control samples (only clay) which implies good insulating characteristics. In addition, the waste incorporation increases the water absorption within the range 4–31% and decreases the compressive strength between 12 and 26%. However, the incorporation of the waste is beneficial as no remarkable changes in the technological properties are observed. These results indicate that the waste has a predominant pore forming effect over a pore filling effect.