Phase Formation of SO_3 Doped Portland Cement Clinker

Impact of the addition of 3%SO3 on the formation of cement clinker minerals in industrials clinker was investigated.Variation of the C4A3$ during sintering process was taken into account.Sintering process of the cement clinker was investigated with DSC-TG,X-ray diffraction and microscopic analysis.Results showed that with a higher SO3 content existed,C4A3$ could formed at 1050 ℃ and decomposed to C3A and C$ from 1290 ℃;C3S formed after 1350 ℃ and f-CaO content dropped to 1% at 1450 ℃.The final clinker had 6.2%C4A3$.C4A3$ decomposed completely when held for 0.5 h at 1450 ℃.Calculation of the theoretical mineral formation was in agreement with the above conclusions.