Study On The Improvement Of Sulphoaluminate Cement Performance And Its Application

Sulphoaluminate cement has the advantages of quick-setting and early-strength,impermeability,freezing resistance,corrosion resistance and low alkalinity.Also it has a very broad application prospect.However,due to the high cost of producting sulphoaluminate cement,there are still some problems of late strength instability or even shrinkage phenomenon to a certain extent which affect a wide range of its application.Based on the mechanism of hydration and hardening,hydration thermodynamics process and the influence of external components on sulphoaluminate cement,this paper introduces the application of admixture and auxiliary cementitious material which makes a comprehensive evaluation of various aspects to reach the purpose of performance optimization.The method of XRD and SEM was used to analyze the phase composition and microstructure of cement hydration products,thereby the influence of external components on sulphoaluminate cement was summarized in order to expand its application range.In this paper,the effects of water-cement ratio,different content such as superplasticizer,lithium carbonate,calcium nitrite,superfine calcium carbonate powder,silica fume and redispersible latex powder,on sulphoaluminate cement.The results was as follows:The water-cement ratio is positively correlated with divergence and the greater the water-cement ratio,the better the workingability of cement slurry;The reduction efficiency of FAD superplasticizer is very high and when the content is 2.5%,the cement divergence can be expanded to 202mm and has a good mobility;Lithium carbonate and calcium nitrite can shorten the coagulation time of sulphoaluminate cement,accelerate the coagulation and hardening of slurry,improve the construction efficiency,while lithium carbonate can also improve the early strength of cement mortar,and nitrite can make the latter strength Steady growth;Superfine calcium carbonate powder and silica fume as the admixture can improve the density of cement slurry and the late strength;In the sulphoaluminate cement mixed with 2.5%of the redispersible latex powder,cement mortar can maintain good workability and its 28d flexural strength up to 11.2MPa.Based on the composite theory of OPC and SAC,OPC-SAC composite cement was prepared by introducing different proportions of Portland cement.The composite cement had good working efficiency and highly mechanical strength.When the OPC content is 30%,the setting time of composite cement is shortened greatly and the flexural strength of 28d is 11.4MPa.It shows that the appropriate amount of OPC cement can shorten the hydration induction period of SAC cement and promote the early hydration and the formation of ettringite(AFt).At the end of this paper,orthogonal design was used to prepare high performance porcelain mortar which compound with sulphoaluminate cement as the main binder material,lithium carbonate,calcium nitrite,superfine calcium carbonate powder and silica fume.The divergence is 189mm,the initial setting is 24min,the final condensate is 56min,the flexural strength is 10.3MPa and the flexural strength is 28.7 days.The hydration products of the mortar were analyzed.The addition of the added components effectively promoted the formation of ettringite,the hydration of hydrated mineral in the mortar system was more intense.At the same time the addition of admixture enhanced the density of cement paste and improved the particle size distribution of cement slurry.So that the modified mortar with good workability,condensation hardening fast,early high strength,stable late strength,is very good to meet the needs of electric porcelain plastic equipment operations.