Effect Of Coagulant On Properties Of Sulphoaluminate Cement

The production process of traditional Portland cement consumes a lot of energy and emits a lot of CO2,which is not conducive to China's environmental protection and the sustainable development of the cement industry.Compared with Portland cement,sulfoaluminate cement consumes less energy which leads to a reduced CO2 emissions,and it shows advantages of early strength,frost resistance,impermeability,corrosion resistance and other excellent characteristics.However,sulfoaluminate cement still has some shortcomings,such as the uncontrollable setting time,the high production cost,and the slowly developed late strength.In order to further improve the performance of sulfoaluminate cement and expand the application of sulfoaluminate cement,this paper focuses on three sections of studies:the effect of single doping borax and lithium salt on the performance of sulfoaluminate cement;the influence of gypsum on borax and lithium salt in the performance of sulfoaluminate cement;the combination effect of borax and lithium on the performance of the sulfoaluminate cement.This paper attempts to find solutions to adjust the setting time of the sulfoaluminate cement without reducing its mechanical properties,and to be kept for reference for the modification of Portland cement,as well as to provide theoretical guidance and technical support for the engineering application of sulfoaluminate cement.This paper also does a further research on the effects of borax on the coagulation time of sulphoaluminate cement,as well as its compressive strength and volume stability.The hydration products of different ages of the cement are tested also.The results show that when the amount of borax is less than 0.1%,the retarding effect on the cement is not obvious,but when the amount of borax is 0.5%,the setting time of the cement is prolonged sharply,which indicates that the effect of varying borax content on the setting time of cement is not stable.Appropriate amount of borax can effectively increase the compressive strength of cement,but when the amount of borax is too much,it will cause the compressive strength of the cement to decrease.The incorporation of borax can effectively delay the hydration process of cement.In order to further study the effect of borax on the performance of sulphoaluminate cement,this paper controls the change of gypsum content in cement to observe the effect of borax on the performance of sulphoaluminate cement under different gypsum content.The results show that:incorporation can effectively reduce the retardation effect of borax on cement and the effect of borax on the hydration products of sulphoaluminate cement.Secondly,the effect of lithium salt on coagulation time,compressive strength,and volume stability of sulphoaluminate cement was studied in this paper,and hydration products of different ages of cement were tested.Here are the results:When the lithium salt is added alone,the addition of 0.03%lithium salt can effectively promote the coagulation of the cement,but with the increase of the lithium salt content,the setting time of the cement basically does not change with the change of the lithium salt content.The incorporation of lithium salt can promote the early hydration process of cement,but is not conducive to the strength development of cement in the later stage.In order to further study the effect of borax on the performance of sulphoaluminate cement,this paper controls the change of the amount of gypsum in cement and observes the effect of lithium salt on the performance of sulphoaluminate cement under different gypsum content.The results show that:Incorporation can effectively reduce the effect of lithium salt on cement setting and the effect of lithium salt on the hydration products of sulphoaluminate cement.Finally,the effects of borax-lithium compound on setting time,compressive strength,volume stability and hydration products of sulfoaluminate cement were studied.The results show that when the borax content is low,the incorporation of lithium can weaken the retarding effect of borax on sulfoaluminate cement.When the borax content is 0.5%,lithium carbonate basically has no coagulative effect on sulfoaluminate cement,while lithium hydroxide has certain coagulative effect on sulfoaluminate cement,but the effect is obviously weakened.The later compressive strength of sulfoaluminate cement was decreased by the addition of lithium with or without borax.Borax-lithium complex does not change the type of cement hydration products,but.The incorporation of 0.1%borax can effectively weaken the coagulative effect of lithium hydroxide on cement and improve the compressive strength of cement,without changing the influence rule of the types of hydration products of lithium hydroxide,but it will slow down the promoting effect of lithium hydroxide on the hydration process of cement.