| High belite sulphoaluminate cement(HBSAC)is a new type of cement developed by combining the advantages of both belite cement and sulphoaluminate cement.High-sulfur belite sulphoaluminate cement(SBSAC)is an HBSAC that incorporates a high-temperature anhydrite mineral phase.The presence of the f-CaSO4 phase increases the hydration rate of Belite and other mineral phases,making the cement a good one.Performance.Combine with the requirements of the 13th Five-Year National Key R&D Program "Preparation and Application of High-resistance Sulfoaluminate Cement-based Materials for Rapid Construction".By designing different mineral compositions,the influence of iron phase content on the clinker firing process,clinker mineral phase composition,structure and cement hydration performance was studied.It provides a theoretical basis for the preparation of fast-hard,early-strength,high-resistance high belite sulphoaluminate cement,and explores a new material for the rapid construction of marine engineering.Based on the High-Sulfr Belite Sulphoaluminate Clinker,different mineral composition recipes were designed according to the change of iron phase content.According to the raw material burnability,raw material thermal analysis,clinker mineral analysis and cement paste strength test data,the series of changes in the clinker firing process were studied,and the clinker calcination system was determined.Using XRF,XRD,SEM and other test methods were used to study the chemical composition,mineral composition,mineral crystal form and mineral morphology of clinker,Cement mortar strength and wear resistance test was carried out and the ICC test was used to analyze the heat release law of cement hydration.Based on this study,the content of iron phase and belite minerals were optimized,and the influence of calcined CaO and f-CaO contained in clinker on the mechanical properties of clinker was explored,and a high-sulfur Belite sulphoaluminate cement with excellent mechanical property was obtained.The research results show that:(1)The increase of iron phase content promotes the sintering of clinker,but at the same time,the firing temperature of the mature material will be narrowed.The suitable calcination temperature for the clinker designed in this study is in the range of 1275??1350?.(2)Part of C2S is present in amorphous form.There is no obvious solution of iron in the crystal,but there is a certain amount of elemental sulfur,and the amount of sulfur dissolved is about 3%;The chemical composition of Ye'elimite is close to that of 4CaO·3Al2O3 1.2SO3 0.1Fe2O3,the amount of aluminum replaced by iron is about 4%,and the amount of replacement does not change significantly with the change of the iron phase content;The chemical composition of iron phase is close to that of 6CaO·Al2O3·Fe2O3.When the content of iron phase is small,it mainly concentrates in the gaps between grains of C4A3S,and they are in a state of mutual fusion.With the increase of the content of iron phase,some of the iron phases exist as separate phases.(3)cement mortar early strength contribution:C4A3S>Ferrite>C2S;and for late strength contribution:Ferrite>C2S>C4A3S;the increase of iron phase content promoted the hydration of the C4A3S,improved the dissolution heat of the cement,and advance the second and third hydration exothermic peaks.The alkalinity of cement paste increases with the increase of iron content.(4)a group of clinker minerals was designed which composed of C4A3S:39%,C2S:25%,f-CS:17%,Ferrite:15%and 4%f-CaO.The clinker 4h compressive strength up to 25.29MPa,7d compressive strength of 59.36MPa... |
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