Calcium aluminate clinkers doped with Na2O were synthesized using analytically pure reagents CaCO3

Al2O3

and Na2CO3 at 1350℃ for 1 h. XRD

SEM and EDS were used to study the phase transformation of calcium aluminates and the leaching performance of clinkers from CaO-Al2O3 system doped with Na2O. The results show that the main phases of clinkers from CaO-Al2O3 system are CaO·Al2O3 and 12CaO·7Al2O3

while those of clinkers from CaO-Al2O3 system doped with Na2O are CaO·Al2O3

12CaO·7Al2O3

Na2O·Al2O3 and Na4Ca3(AlO2)10

when the molar ratio of CaO to Al2O3 is 1.0. Some of the Na2O forms compounds containing Na2O

the rest is doped in 12CaO·7Al2O3

meanwhile nearly none of Na2O is doped in CaO·Al2O3. With the increasing of the Na2O content in clinkers

the amounts of 12CaO·7Al2O3 and Na4Ca3(AlO2)10 increase while the amount of CaO·Al2O3 decreases

and the crystallinity of 12CaO·7Al2O3 and Na4Ca3(AlO2)10 decrease while that of CaO·Al2O3 increases. Due to the doping of Na2O

the leaching performance of alumina in the clinkers using the sodium carbonate solution is improved and the space groups of CaCO3 in the leached residues are changed from R-3CH and P63/MMC to only R-3CH.