Heat of Hydration and Characterization of Reaction Products of Adiabatically Cured Fly Ash and Slag Mixtures

Abstract

The hydration of cementitious materials is an exothermic process which results in significant temperature increases in large masses of these materials. The thermal environment under these conditions is nearly adiabatic. The heat of hydration of cementitious aluminosilicate blend materials incorporating fly ash and granulated blast-furnace slag was calculated from the adiabatic temperature rise. Additional reaction of siliceous fly ash with alkaline solutions results in the formation of zeolitic reaction products. Studies were carried out to characterize the hydration products by X-ray diffraction and through analysis of solutions. In addition, zeolitic reaction products were prepared by reacting the pure Class F fly ash at 90°C with NaOH and different anions. This study has implications for general thermal properties of hydrating cementitious materials, and for costeffective immobilization of radioactive and chemical waste cations and anions.