Comparison of ground bottom ash and limestone as additions in blended cements

The number of fluidized bed power plants is growing rapidly due to economic and environmental benefits. These facilities produce larger quantities of bottom ash than conventional boilers. This ash exhibits pozzolanic activity once ground, but due to regulation limitations this by-product is nowadays destined to landfill. Blended cements are the most common cements in Europe and their consumption is continuously growing due to the reduction of environmental impact they allow. In this work, ground bottom ash (GBA) is characterized to determine whether it is suitable for blended cements' production. This GBA was used in ratios of 10, 20 and 40 % as cement replacement. At the same time, it was compared with type I cement without additions and also with the second most used addition in blended cements: limestone. The cements with GBA showed acceptable performance to produce general purpose cements in the frame of present regulations, reaching 52.5 MPa at 28 days for 10 % of substitution. When compared with limestone, the cements with GBA presented higher compressive strength, better durability and a slight reduction in workability. At the same time, GBA led to higher clinker reductions, thus directly causing lower environmental impacts, and also indirect benefits from the prevention of the disposal in landfill of this bottom ash from fluidized-bed boilers.