Utilization of circulating fluidized bed fly ash for the preparation of foam concrete

Circulating fluidized bed combustion (CFBC) fly ash (CFA), which has not been recycled in large scale due to its later volume expansion yet, was utilized for the preparation of foam concrete. To investigate whether a large volume of pore in the foam concrete would reduce the expansion from the CFA or reduce the shrinkage of foam concrete. A series of manufacturing parameters, such as quick lime and aluminate cement dosages, water to solid ratio (W/S), CFA fineness and type, chemical activators and so on, were investigated based on the density and compressive strength of specimens and the performances of products were also tested in this paper. The results show the most reasonable dosages of CFA, quick lime, and aluminate cement were 70%, 8%, and 2%, respectively. The addition of quicklime or/and aluminate cement could accelerate the setting and hardening rate of slurry. To improve the compressive strength, the finer CFA is better, and W/S should be reduced as low as possible. Incorporating 0.05% TEA or/and 0.5% Na2SO4 into the slurry can significantly enhance the compressive strength of the foam concrete. Encouragingly, the compressive strength, frost-resistance and thermal conductivity of products are good.