Geo-polymerization technique for brick production from coal ash and cigarette butts

Innovative approaches are under research to produce sustainable bricks from waste materials in order to minimize the significant environmental impacts of conventional brick industry. In this study, geo-polymerization technique was used for the first time to produce sustainable light-weight bricks from cigarette butts (CBs) and coal ash. Various Na2SiO3: NaOH and coal ash: activation liquid ratios were studied to be able to obtain well-formed bricks. The CBs were added in coal ash in two ways: either in dry form or previously soaked in the activation liquid before they were mixed with the coal ash. The percentage of CBs mixed in coal ash was varied between 5% and 15%. The density, compressive strength and water absorption capacities of the geo-polymer bricks were elucidated at time intervals of 7, 14 and 28 days. The results showed that, bricks produced with Na2SiO3: NaOH ratio of 2:1, (coal ash and CBs): activation liquid ratio of 3.5:1 and 15% treated CBs achieved a low density (1563 kg/m(3)) while sustaining its compressive strength (11.1 MPa) complying with the standards. In addition, lower water absorption was obtained with the bricks containing treated CBs in comparison to the ones with untreated CBs. In conclusion, geo-polymerization shows a high potential as a sustainable method for the light-weight brick production from CBs and coal ash. (C) 2020 The Authors. Published by Elsevier B.V.