Preparation And Shielding Performance Of New Boron-containing Cement Clinker

With the continuous development and progress of nuclear science and technology,the research and development of radiation shielding materials is of great significance in the modern society,which attaches great importance to radiation protection and environmental protection.It is especially important to develop a special new type of radiation protection cement because of the problems of barium,strontium and boron cement,which have the disadvantages of simple radiation protection effect,poor thermal stability,and high calcination temperature.This paper will prevent neutron ray better effect of boron into cement clinker,to study the effects of silicate raw materials,sintering of Portland cement clinker composition,structure and properties;and discusses the dynamic mechanism of the formation process of Portland cement clinker doped B2O3,to obtain the kinetic data of new boron silicate cement clinker formation;the formation of structural stability of the new clinker by high temperature solid phase reaction changed the original composition of clinker,the design of a new type of boron containing anti radiation cement clinker system,the optimum calcination system optimum composition and the clinker clinker was determined by orthogonal experimental method.Combined with modern testing methods such as XRD,SEM(EDS),f-CaO and 252Cf neutron measuring instrument,the composition and structure,mechanical properties and neutron shielding performance of clinker are discussed.The experimental results showed that B2O3 was introduced into the raw materials can improve the flammability of raw materials,so that the liquid phase appeared at lower temperature and the viscosity decreased significantly,which accelerated the formation of C3S.When the content of the B2O3 is 3%and calcination temperature is 1390?,the mechanical performance of clinker is optimal,in 3 d and 28 d age,its compressive strength is 28.1 MPa and 48.2 MPa,respectively.Besides,its calcination temperature 60?lower than the Portland cement clinker,which is beneficial to reduce the energy consumption of firing.The introduction of B2O3 accelerated the formation of C3S minerals in clinker,the main reason of which is that the C3S formation reaction conforms to Glinstling kinetic equation and the presence of B2O3 makes the rate constant of C3S mineral formation larger and the activation energy of the formation decreases.However,at a high temperature of 1430?,excess B2O3 was unfavorable for the burnability of the raw meal,and inhibited the formation of C3S,which increased the f-CaO content in the clinker.Under the condition of doping new boron-containing minerals,the optimum mineral composition of new boron-containing cement clinker is obtained by orthogonal optimization:C3S-56.77%,C2S-15.84%,C3A-8.06%,C4AF-10.17%,X-4.0%;Orthogonal optimization to get the best calcining system is:incubate at 1390? for 80min,and two-stage cooling;Under the conditions of optimum clinker composition and calcining system,the compressive strengths of the prepared small-scale specimens of boron-containing radiation-proof cements at 3d and 28d were 27.5 MPa and 50.4 MPa,respectively,and the mechanical properties were good.The incorporation of new boron-containing minerals,not only the energy consumption of firing is reduced,and the performance of the cement is improved,but also the ability to prevent neutron radiation is improved.the neutron shielding performance of the boron-containing radiation-proof cement increases with the increase of the content of boron-containing minerals,and the neutron shielding ratio of 4%at the same thickness is increased from 10.5%to 78%of the blank sample,changes little with increasing temperature,and increases with the increases of the sample's.thickness.