Experiment And Analysis On Static And Dynamic Mechanical Properties Of Lunar Soil Simulant Cured With Sodium Silicate

The construction of lunar base in the future needs a lot of building materials.Lunar soil is the largest resource on the moon.If it can be reasonably used,the production cost of lunar base construction will be effectively reduced.The lunar soil simulant geopolymer is a common method to strengthen the lunar soil simulant,and it has certain feasibility in lunar construction.In this paper,lunar soil simulant solidified with sodium silicate is proposed to study its mechanical properties,so as to provide a certain experimental basis for the development of lunar building materials.By carrying out unconfined compressive strength test,splitting test,direct shear test and SHPB test,the influence of sodium silicate content(1%,3%,5% and 7%),curing temperature(25℃,50℃,85℃ and 120℃)and curing age on the mechanical properties of lunar soil simulant was studied.Combined with SEM test and XRD test,the microstructure of sodium silicate simulated lunar soil was analyzed,and the following conclusions were drawn:(1)The unconfined compressive strength test reveals that there were substantial differences in the compressive strength of the lunar soil simulant depending on the sodium silicate concentration and curing temperature.When sodium silicate contents keep rising,lunar soil simulant’s strength increased initially,then declined.The compressive strength of lunar soil simulant cured for 28 days reached its maximum when the sodium silicate content was 5% and the curing temperature was 85°C.Additionally,the total energy and elastic energy in the lunar soil simulant system also reached their maximums at these conditions.(2)The splitting test of sodium silicate solidified lunar soil simulant was carried out,lunar soil simulant’s tensile strength increased with loading rate keeping increasing,especially when loading rate exceeded 2mm/min,the increase of tensile strength was larger.The addition of sodium silicate significantly improved lunar soil simulant’s tensile strength.When the sodium silicate content was 5%,lunar soil simulant’s tensile strength reached the maximum.There is a linear relationship between tensile deformation modulus and tensile stress of all lunar soil simulant samples.(3)Lunar soil simulant’s shear strength and shear characteristics are investigated using a direct shear test.The findings demonstrated that the lunar soil simulant’s shear stress-displacement curve primarily exhibited strain softening features and that the shear strength envelope was parallel to one another.Lunar soil simulant’s shear strength reached the peak at 5% sodium silicate content.The lunar soil simulant’s initial shear deformation modulus and peak shear deformation modulus both peaked at this point.(4)Through SHPB test,the influence of sodium silicate content and curing age on dynamic compressive properties of lunar soil simulant under different impact pressure was studied.The results showed that lunar soil simulant’s dynamic compressive strength increased with the impact pressure and curing age going up,and the degree of specimen breakage became more and more serious with the impact pressure increasing.Lunar soil simulant’s dynamic strength increased initially with an increase in sodium silicate content before decreasing and peaking at 5% sodium silicate,where the incident energy was the maximum,and the absorption energy was the minimum.With the increase of sodium silicate content,the change of dynamic compressive strength of lunar soil simulant samples was more affected by the average strain rate.With the increase of absorbed energy,the damage degree of lunar soil simulant samples became more serious.(5)By SEM test and XRD test,lunar soil simulant’s microstructure was obtained.The results show that the sodium silicate’s incorporation can effectively improve lunar soil simulant’s inner density.The development of AFt,N-A-S-H,hydrated calcium silicate,and other gel products in the system is stimulated by the alkaline environment that sodium silicate provides for the lunar soil simulant.Through adsorption,filling,and encapsulation,these compounds decrease the porosity between the particles of the lunar soil simulant,improving the material’s mechanical properties.Figure [58] Table [12] Reference [102]...