Dry-Press Prefabrication of Circulating Fluidized Bed Fly Ash Components: Key Parameters and Strength Characteristics

Introduction: Circulating Fluidized Bed Fly Ash (CFBFA) differs from conventional Pulverized Coal Fly Ash (PCFA), so PCFA-based processing routes are not readily applicable. Stockpiled CFBFA occupies land and can cause dust dispersion and leaching-related concerns. This study used the dry pressing method to prepare CFBFA gel and tested the effects of initial moisture content, dry density, pressing time, and curing age on its strength development. Methods: Specimens were prepared from CFBFA and water using a dry compaction method. The effects of moisture content, dry density, and curing age on the compressive strength of the fly ash gel were investigated. Results: Curing age and dry density showed a positive effect on compressive strength. The specimens achieved the maximum compressive strength of 12.47 MPa after 90 days of curing at a dry density of 1.2 g/cm3. Discussion: Higher compaction produced a denser contact network, while curing promoted continued reaction and product formation, together driving strength gain. The UCS level suggests potential for non-structural building components, but durability and leaching tests are still needed to confirm service suitability. Conclusion: This study shows that activator-free dry pressing can transform CFBFA into a usable cementitious gel. Proper moisture control and compaction are critical for strength development. The resulting material meets basic requirements for road precast components and offers a low-carbon, waste-based alternative, pending durability and environmental verification.