Comparative Study on the Characteristics of Fluidized Bed Combustion and Pulverized Coal Combustion Bottom Ash Bricks

The utilization of fly ash as bricks has been extensively researched and proven effective; however, the potential of bottom ash remains unattempted mainly due to its coarser particle size. In particular, fluidized bed combustion (FBC) bottom ash, derived from a more environmentally friendly power generation process, deserves greater attention for its potential applications than conventional pulverized coal combustion (PCC). This study compares the properties of bricks made from PCC and FBC bottom ash, shedding light on their respective characteristics and potential uses. The main techniques used for the characterization are scanning electron microscopy, X-ray diffraction, and FT-IR. Compressive strength, water absorption, and bulk density were obtained by performing several tests on both bricks samples. The results showed that the strength development phenomena are initially faster for FBC bottom ash than PCC due to free silica and alumina. Due to more amorphous phases present in PCC bottom ash, the hydration product is larger than FBC bottom ash, resulting in more strength. The samples produced by both types of bottom ash require at least 10 M NaOH, 24 h curing at 65 °C temperature for fulfilling the criteria of lightweight building bricks of NW category as per ASTM C-62. Samples produced by PCC bottom ash satisfy the building bricks standard of MW category requirements at the same parameters.