Preparation And Hydration Properties Of Radiation Protection Cement

Radiation protection materials are an important guarantee for human health,nature and environmental safety.It is also one of the prerequisites for the widespread application of nuclear technology.It is a key functional material for scholars and experts at home and abroad.It is very important to develop radiation protection cement（RPC）because of the problems of ionization and cracking of radiation concrete and barium,strontium and boron cement,which have the disadvantages of simple radiation protection effect,poor gelation and stability,and high calcination temperature.In this paper,a kind of cement with radiation protection function is prepared by adding a certain amount of boron-containing compound with good shielding ability in industrial raw materials to form multi-system clinker.The hydration properties of RPC such as mineral composition and morphology,setting time,hydration heat and mortar strength were measured by XRD,SEM（EDS）,hydration heat analyzer and ²⁵²Cf neutron measuring instrument.Hydration product composition and morphology of RPC are studied.The relationship between composition,morphology,structure and radiation properties of RPC was discussed,and the appropriate compound type and content of shielding radiation are determined.The experimental results show that radiation clinker prepared at 1400℃is related to the kind and content of the compound.With the increase of the content of Y1 and Y3,the content of anti-radiation mineral X increased gradually,and the change of Y2 is not obvious.The incorporation of the compounds change the morphology and size of the clinker mineral phase.The incorporation of compounds affects the relative content of C₃S and C₂S minerals in clinker to some extent.The results of EDS show that the clinker contains the mineral phase X formed by some shielding elements.The standard consistency water consumption,setting time and volume stability of RPC are closely related to the type and content of compounds.In terms of standard consistency water consumption,the amount of cement used in the preparation of Y1 decrease sharply with the increase of the content,and reach the minimum value of 24.9%when the content is3%;Y2 is not obvious with the increase of the content;Y3 decrease firstly and then increase,and the water consumption is kept above 26%.Regardless of what kind of compound will significantly extend RPC’s setting time.In the case of the initial setting time,the prolongation time of RPC by the incorporation of Y2 is shorter than that of Y1 and Y3,and the difference between the initial setting time of Y1 and Y3 is small.The final setting time of RPC prepared with Y1,Y2 and Y3 is basically the same as the change of compound content,and increases with the increase of the content.The final setting time of incorporation of Y2 is shorter than that of Y1 and Y3.This may be the incorporation of Y2 on C₃A,C₃S mineral formation has a smaller impact.No matter what kind of compound prepared by cement stability of RPC are qualified.The compressive and bending strength of RPC prepared by the incorporation of the compound is lower than that of the control sample R,but the degree is different.With the increase of the content,the compressive and bending strength of RPC prepared by Y1 were decreased at 3d,7d and 28d,and the early strength is lower and the later period increases.Y2is lower at 3d,7d and 28d,and the bending strength is not obvious.Y3 is stable at 3d,7d and28d,and the early strength is higher and the later stage is smaller.The total amount of hydration heat of RPC prepared with different compounds increases with the increase of hydration time,but the total heat is different.The total heat in the 7th day with the addition of Y2 and Y3 are similar to that of the contrast sample.The total heat of Y1and Y3 was different.Hydration rate of the maximum,are concentrated within 0.5d.RPC’s hydration products are mainly C-S-H,CH,AFt,aluminates hydrate and boron hydrate.With the prolongation of age,the diffraction peak of aluminate hydrated decreases slowly,and the change of C-S-H diffraction peak is not obvious.The diffraction peak of CH,AFt and hydrated borate gradually increases,which may be related to the crystal growth and grain size.In the SEM observation,fiber-like AFt,hexagonal plate-like CH are clear,C₃BH₁₂ is sheet,CBH₅ is fibrous.The neutron shielding performance of RPC varies with the type and content of the compound.The neutron shielding performance of RPC formed by Y1 and Y3 are better,and the shielding rate are 88.4%and 93.3%when the content is 3%.This may be related to boron hydrates with larger absorption cross sections.