Research On Mineral Matching Of Cement Clinker Used In Nuclear Engineering

It is a significant strategy of energy sources in China that constructing and applyingnuclear power station safely and efficiency, which was showed distinctly in “Middle-longterm development strategy of nuclear power(2005～2020)”. At present, the criterions andcodes applied in nuclear power plants were mainly cited from U.S, France, Russia et al.Cement applied in nuclear power plant purchase at local referring to the cement criterion ofFrance, which leads to bad adaptability between cement and other materials due to differerenttypes of cement. To strengthen the standardization and unification during the constructionprocess of nuclear power plant, all materials and operation were required to set up uniformcriterion, especially cement used in nuclear power plant. In terms of the requirements ofconcrete in nuclear power station such as bulk, highly anti-crack ability, etc., this kind ofcement should be characterized of high early and later strength, the lower hydration heat,and lower shrinkage.This study is financed by the National Science-technology Support Plan Projects“Thepreparation of nuclear engineering cement with high strength and moderate heat”. Theclinkers with different mineral match were experimentally burnt. With chemical analysis,petro-graphic analysis, physical properties tests, scanning electronic microscope(SEM),energy dispersive spectrometer(EDS), X-ray diffraction(XRD), thermo analysis(TA),Differential Scanning Calorimeter(DSC), optimized mineral match, clinker’s properties andmicrostructure were studied.The burnabilities and mineral constituent of nuclear engineering cement with differentKH,SM,IM were studied, and the matching relationship was discussed. The results show thatthe suitable range of KH is less than0.92, SM2.2~2.8, IM0.7~0.9.In this range, theburnability is well, The liquid phase decreases when SM is more than2.8, crystalmisdistribution. The clinker burned at normal firing temperature, the crystal has uniformdistribution, edge sharpness, the particle size is between20~40μm，well crystallization.Cement properties of different mineral constituent with a certain amount of gypsum wasstudied, the physical properties of cement burned at normal firing temperature is very good,fluctuates as the change of C3S and C3A content. In addition, the water requirement for normal consistency, setting times and soundness are slightly affected by the small change inmineral composites. The compressive strength of28days reach55MPa,with the highest62MPa, dry shrinkage of28days is less than0.1%, hydration heat can attain the moderateheat Portland cement standard. And other properties could arrive at the requirements ofnuclear engineering program.The hydration mechanism was studied through the hydration heat and hydration rate ofnuclear engineering cement with different mineral constituent, the results show that duringthe setting range, the hydration rate changes with C3A content, and the hydration exothermicpeak forward lead. the hydration heat increases with the increase of C3S content. Furthermore,some test techniques i.e. XRD,SEM and TG-DSC were applied to research the setting processof specimens, hydration products and structure of setting pastes.