Synthesis and properties of calcium sulphoaluminate using fluidised-bed boiler ash.

Various shrinkage-reducing agents and expansive admixtures have been developed to decrease the drying shrinkage of concrete at construction sites. However, concrete with added shrinkage-reducing agents has been reported to exhibit low frost resistance and low compressive strength during the early curing stages. It is possible to use an expansive admixture such as the K-type additive, composed of calcium sulphoaluminate, which contains an alumina source such as bauxite. Here, we develop a calcium sulphoaluminate expansive additive using industrial byproducts (fluidised bed boiler ash) and study the properties of the synthesised calcium sulphoaluminate using a micro-mechanical model. The hydration temperatures, drying shrinkage sand mechanical characteristics of mortar samples incorporating the manufactured calcium sulphoaluminate expansive additive are experimentally examined. The results show that the calcium sulphoaluminate additive generates a higher hydration temperature and an enhanced length change property. Finally, hauyne, developed following a suitable sintering process, may be an effective alternative calcium sulphoaluminate expansive additive. [ABSTRACT FROM AUTHOR]