Elaboration of a sustainable bottom ash geopolymer material

¹ Department of Civil and Environmental Engineering, University of Balamand, 110, Lebanon
² Departement of Génie Civil & Environnemental, IMT Nord Europe, CERI Matériaux et Procédés, 59500 Douai, France

^* Corresponding author: georges.aouad@imt-nord-europe.fr

Abstract

The use of Ordinary Portland Cement (OPC) has been the primary material used in the construction industry. Its production leads to 5% to 7% of total CO₂ emissions and 14% of the total global energy emissions [1,2]. The pollution caused by OPC production has encouraged researchers to discover new environmental and sustainable materials such as geopolymers [2]. The main objective of this study is to investigate the mechanical properties of metakaolin-based geopolymers made with bottom ash to produce an eco-friendly material while reducing waste generation. The following research determines the mechanical properties of French metakaolin-based geopolymer produced with bottom ash at different mass substitution rates ranging from 0% to 15%. The solid powders were mixed with a sodium-based alkali activator and poured into 4x4 cubical molds. The four different mix designs were cured at ambient temperature and varied according to the different percentages of bottom ash (0%, 5%, 10%, and 15%) inserted. The mechanical properties of the several mixes were assessed by the use of a UTM compression test machine on the respective days of testing: 7, 28, and 90 days. Results demonstrated that the geopolymer mortars produced with bottom ash gave promising mechanical properties regardless of the mass substitution rates inserted in the mixes. This behavior has induced the potential for incorporating such waste in producing a sustainable and eco-friendly cementitious material. In conclusion, the use of bottom ash as a recyclable source material in geopolymer mortar formulation has highlighted the importance of this development as a sustainable solution. The effectiveness of a study where the compressive strength showed high results when compared to OPC is encouraging.