Hydration Properties of Portland Cement Paste with Boron Gangue

In order to prepare a good radiation shielding concrete with a proper setting time and a high strength, the hydration properties of cement with boron gangue were investigated by the methods of XRD, isothermal microcalorimetry, TG/DSC, and FTIR. The results demonstrated that it was mainly related to the insoluble matter CaB2O4 center dot 4H(2)O and Ca(H2BO3)(2)center dot 4H(2)O that boron gangue could severely inhibit the cement hydration. Boron gangue made a significant retardation on Portland cement hydration with the form of BO33- and BO45-, which caused an obvious retardation of C(3)A and C3S hydration with an insoluble coat and a low solubility of calcium ion in the solution. Therefore, it is important and necessary to take into consideration the chemistry of borates in aqueous and the kind of cement-based or cementitious materials used for radiation shielding concrete with boron or boron compounds, especially for the materials with a high content of C(3)A and C3S.