Influence of Sulfate on Cement Mixtures Containing Fly Ash or Blast-Furnace Slag
N. Bhanumathidas and N. Kalidas
Appears on pages(s):
alumina; blast-furnace slag; fly ash; gypsum; lime; port-land
Both fly ash and granulated blast-furnace slag contain reactive alumina, the strength potential of which can be tapped through addition of gypsum. This has resulted in the development of cementitious mixture of fly ash, lime and gypsum, called FaL-G. In the presence of gypsum, some fly ash-lime mixtures render 3 to 6 times strength enhancement at all ages. The authors have found that high-volume fly ash blended portland cements also increase in strength with the addition of gypsum or anhydrite. Similar behaviour is observed in ground granulated blast-furnace slag blended portland cements also. This improved strength is attributed to the formation of additional calcium sulphoaluminate hydrates. The research findings are highly significant from standpoint of conservation of agricultural soils, minerals and energy, and better utilization of fly ashes and blast-furnace slag in tropical climates.