Use of bottom ash from olive pomace combustion in the production of eco-friendly fired clay bricks

Olive pomace bottom ash was used to replace different amounts (10-50 wt%) of clay in brick manufacturing. The aim of this study is both studying bricks properties and showing a new way of olive pomace bottom ash recycling. Properties of waste bricks were compared to conventional products following standard procedures in order to determine the maximum waste percentage. The amount of olive pomace bottom ash is limited to 20 wt%, obtaining bricks with superior engineering properties when 10 wt% of waste is added. Adding higher amount of waste (30-50 wt%) resulted in bricks with water absorption and compressive strength values on the edge of meeting those established by standards. Therefore, the addition of 10 and 20 wt% of olive pomace bottom ash produced bricks with a bulk density of 1635 and 1527 kg/m3 and a compressive strength of 33.9 MPa and 14.2 MPa, respectively. Fired bricks fulfil standards requirements for clay masonry units, offering, at the same time, better thermal insulation of buildings due to a reduction in thermal conductivity of 14.4% and 16.8% respectively, compared to control bricks (only clay).