FLUIDIZED BED COAL-BARK FLY ASH GEOPOLYMER WITH ADDITIVES CURED AT AMBIENT TEMPERATURE

Abstract

: In this research, the properties of fluidized bed coal-bark fly ash geopolymer mortar containing
additives viz., ordinary Portland Cement (OPC) and micro silica (MS) were studied. The fluidized bed coalbark fly ash was a waste from a power plant boiler in Khon Kaen, Thailand. The geopolymer mortar was made
from fluidized bed coal-bark fly ash, sand, sodium silicate solution, NaOH solution, and additives. The
additives were used to replace the fluidized bed coal-bark fly ash at the level of 0 - 15 % by weight. The mortars
with liquid alkaline/ash ratios of 0.9-1.4, sodium silicate/NaOH ratios of 0.33-3.00, NaOH concentrations of
5-15 molars, OPC and micro silica contents of 0 - 15 % by weight of fly ash, and curing at ambient temperature
were tested. The geopolymer mortars with 28-day compressive strengths between 5.5 and 27.0 MPa and
densities between 1970 and 2175 kg/m3 were obtained. The addition of OPC and micro silica enhanced the
strength development of geopolymer mortar with the optimum OPC content of 10 % and micro silica content
of 15 %. It is shown here that the fluidized bed coal-bark fly ash geopolymer mortar containing OPC and micro
silica as additives with ambient temperature curing possesses sufficient strength. The use of this product can
reduce the energy consumption in cement production and increases the sustainability of construction industry.