Reuse of Industrial and Agricultural Waste in the Fabrication of Geopolymeric Binders: Mechanical and Microstructural Behavior

Resource recovery from waste is one of the most important ways to implement the so-called circular economy, and the use of alkali activated materials can become an alternative for traditional PC-based materials. These types of materials are based on waste resources involving a lower carbon footprint and present similar or high properties and good durability compared to that Portland cement (PC). This research work proposes using new waste generated in different types of industries. Four waste types were employed: fluid catalytic cracking residue (FCC) from the petrochemical industry; ceramic sanitary ware (CSW) from the construction industry; rice husk ash (RHA); diatomaceous waste from beer filtration (DB) (food industry). FCC and CSW were employed as precursor materials, and mixtures of both showed good properties of the obtained alkali activated materials generated with commercial products as activators (NaOH/waterglass). RHA and DB were herein used as an alternative silica source to prepare the alkaline activating solution. Mechanical behavior was studied by the compressive strength development of mortars. The corresponding pastes were characterized by X-ray diffraction, thermogravimetric analysis, and microscopy studies. The results were satisfactory, and demonstrated that employing these alternative activators from waste produces alkali activated materials with good mechanical properties, which were sometimes similar or even better than those obtained with commercial reagents.