Study On The Rapid Setting And Hardening High Belite Calcium Sulfoaluminate Cement Clinker

Rapid setting and hardening high belite sulfoaluminate cement clinker,developed by Tangshan Polar Bear Building Materials Co.Ltd.,revealed several advantages like fast setting,rapid hardening,early strength,high strength,micro expansion,low dry shrinkage,frost resistance,impermeability,resistance to corrosion etc.when plaster being grounded in to make cements.Studying the clinker sintering mechanism and microstructure for cement clinker could provide data reference and guidance for the industrial production process,which is of great significance for energy conservation and emissions reduction of cement production.The sintering process,optimum calcination system and the influence of free calcium oxide in cement clinker were investigated by X-ray Diffraction?XRD?,Thermogravimetric?TG?-Differential Scanning Calorimetry?DSC?,Scanning Electron Microscope?SEM?and Mercury Intrusion Porosimetry?MIP?.The microstructure morphology of rapid setting and hardening high belite sulfoaluminate?HBCSA?cement and its causes for outstanding properties were also confirmed.Results show that:?1?Rapid setting and hardening high belite sulfoaluminate cement clinker's calcining temperature range is 1250?-1350? and the best calcining system for 1300? is calcined under 0.5h.In the clinker sintering process,C₄A₃S?was mainly produced in large number from 1181? to 1198?.As with the decomposition of 4CaO·2SiO₂·CaSO₄ from 1200? to 1250?,a great number of C₂S and CaSO₄were born.?2?HBCSA cement clinker's mineralogical composition distribution was more uniform and smaller in grains,basically under 5 microns,which is similar to CSA clinker yet less than the size of the OPC clinker minerals;C₂S phase in irregular shape was partly solid dissolved with CaSO₄ and C₄A₃??? in cement clinker hydration,leading to quick hydration in response.Big holes at about 10?m and plenty of0.1-1.0?m microspores existed in HBCSA cement clinker,which,after grinding,could increase the inner specific surface area in clinker,leading to hydration acceleration.?3?Right amount of f-CaO can significantly improve the early strength of HBCSA cements,but less effect on the late strength.In addition excessive f-CaO would cause cement cracking expansion.In this research,f-CaO content in HBCSA cement clinker at around 0.8%was optimum,which could accelerate early hydration rate and bring forward administrative heat peak.Meanwhile,superabundant f-CaO could reduce HBCSA cement early hydration rate and delay the administrative heat peak.As with the increase content of f-CaO,cement total heat release increased simultaneously.