Methods for the control of volume stability of sulfur-rich CFBC ash cementitious systems

摘要

The destructive expansion of circulating fluidised bed combustion (CFBC) ash is the bottleneck problem for its utilisation in building materials. The effect of mixing pulverised-coal combustion (PCC) fly ash or clinker as well as autoclave curing on the expansion of a sulfur-rich CFBC ash cementitious system was investigated. It was found that the linear expansion ratio of CFBC ash-PCC fly ash-clinker mortar with no more than 3-5% SO_3 is close to that of cement mortar. Moreover, the linear expansion ratio of CFBC ash-clinker-water paste dropped to less than 0-5 mm/m after autoclave curing. This study suggests that the volume stability of a CFBC ash cementitious system can be controlled effectively through autoclave curing or limiting the content of total SO_3 to below 3-5%.