Micro-expansion Of Moderate Heat Portland Cement With High Magnesium Produced By New Dry Process Kiln

Moderate heat Portland cement(MHPC)has characteristics of low heat of hydration and high content of Mg O.The Mg O exsiting as periclase in MHPC will be gradually hydrated to form Mg(OH)2,which could produce the micro-expansion in hardened cement stone to compensate shrinkage and prevent the cracks in mass concrete.In China,MHPC has received much attention and be extensively applicated in large-scale hydropower projects.In this paper,the content,morphology and distribution of Mg O in MHPC clinkers produced by lab or new dry process kiln have been researched,and the micro-expansion of the MHPC has also been analysed.The influence of process parameters of MHPC clinker with high content of Mg O(>5%),such as the calcined and cooling system,mix ratio of raw materials and the fineness etc.,on periclase and micro-expansion has been studied through Lab experiment.The MHPC has been produced in new dry process kiln according to the results of Lab experiments,which indicated that the optimized micro-expansiton of MHPC could be obtained when 6.5~7.5%content of Mg O,0.87-0.90 of saturation rate,2.6~2.8 of SM,0.75~0.85 of IM and within 0.3% content of Alkali content were adopted.The study provided guidance for the production of MHPC with high content of MgO.