Abstract
The fabrication of high-performance cement-based materials has benefited greatly from the extensive use of graphene and its derivatives. This paper studies the effects of graphene sulfonate nanosheets (GSNSs) on sacrificial cement paste and mortar (the tested materials) and other siliceous sacrificial materials, especially their ablation behaviors and mechanical properties. Decomposition temperatures and differential scanning calorimetry were used to examine how different contents of GSNSs determines the corresponding decomposition enthalpy of the tested materials and their ablation behaviors. Molecular dynamics was also used to clarify the mechanism how the GSNSs work in the CSH (calcium silicate hydrated)/GSNSs composite to increase the resistance to high temperature. The experimental results show that: (1) the contents of GSNSs at 0.03 wt.%, 0.1 wt.%, and 0.3 wt.% brought an increase of 10.97%, 22.21%, and 17.56%, respectively, in the flexural strength of siliceous sacrificial mortar, and an increase of 1.92%, 9.16%, and 6.70% in its compressive strength; (2) the porosity of siliceous sacrificial mortar was decreased by 5.04%, 9.91%, and 7.13%, respectively, and the threshold pore diameter of siliceous sacrificial mortar was decreased by 13.06%, 35.39%, and 24.02%, when the contents of GSNSs were 0.03 wt.%, 0.1 wt.%, and 0.3 wt.%, respectively; (3) a decline of 11.16%, 28.50%, and 61.01% was found in the ablation velocity of siliceous sacrificial mortar, when the contents of GSNSs were 0.03 wt.%, 0.1 wt.%, and 0.3 wt.%, respectively; (4) when considering the ablation velocities and mechanical properties of siliceous sacrificial materials, 0.1 wt.% GSNSs was considered to be the optimal amount; (5) the GSNSs contribute to the reinforced effect of GSNSs on CSH gel through the grab of dissociated calcium and water molecules, and the chemical reaction with silicate tetrahedron to produce S–O–Si bonds. These results are expected to promoting the development of new kinds of siliceous sacrificial materials that contain GSNSs.
Highlights
Siliceous sacrificial materials, due to its encasing function, are widely used to prevent radioactive materials from leaking in serious nuclear accidents
Molecular dynamics was carried out to clarify the mechanism how the graphene sulfonate nanosheets (GSNSs) work in the CSH/GSNSs composite to increase the resistance to high temperature
Molecular dynamics was performed to probe the mechanism how the GSNSs works in the CSH/ GSNSs composite to increase the resistance to high temperature
Summary
Due to its encasing function, are widely used to prevent radioactive materials from leaking in serious nuclear accidents. In the European Pressurized Water Reactor, sacrificial material is an important part of core catcher. Materials 2020, 13, 4824 non-volatile fission products, partially or totally oxidized cladding and fuel material). Radioactive fission products can be enwrapped by the matrix formed by molten SiO2 and Zr in the corium can be oxidized by the SiO2 from sacrificial concrete [1]. Thermal properties of siliceous sacrificial materials, especially their ablation behavior, contribute greatly to the mitigation of serious nuclear accidents. Since siliceous materials are increasingly applied in nuclear power plants worldwide, it is significant to investigate siliceous sacrificial materials and their ablation behavior
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