Abstract
In recent decades, lightweight concrete production has undergone significant development, and its consumption is increasing worldwide due to its importance in construction and infrastructure. A significant advancement in lightweight concrete technology was the development of industrially manufactured lightweight aggregates. Lightweight concrete offers several advantages, including reduced dead loads in structures and more effective building insulation compared to OPC. Additionally, sustainable building materials, such as geopolymers, are used to address ecological problems associated with the production of Portland cement. Lightweight geopolymer concrete combines the advantages of the two approaches. They can be produced by mixing low-specific-gravity natural or synthetic aggregates with aluminosilicate binders and an alkaline solution. In this study, geopolymer samples were produced using fly ash as an aluminosilicate precursor and expanded perlite as a partial replacement for the CEN standard sand by weight. The production of lightweight geopolymers using expanded perlite and the effects of production conditions on the mechanical and microstructural properties of the geopolymers were investigated. Geopolymer samples were produced using different water amounts and cured at different curing temperatures, and their effects on the properties were investigated. Findings revealed that using expanded perlite, particularly at 70°C curing temperature and a specific water amount (to obtain a flow diameter of 15 cm), significantly decreased density while maintaining mechanical properties by obtaining acceptable compressive strength, approximately 75% of that of the reference sample, resulting in an effective lightweight geopolymer mortar that supports sustainable practices.