Experiment And Analysis On Dynamic And Static Mechanical Properties Of Lunar Soil Simulants And Its Geopolymer

The moon is rich in mineral resources.Establishing a stable and safe lunar base to mine resources has become the next aggressive scientific research goal of mankind.Using lunar in-situ resources for the production of base building materials can effectively save costs and reduce risks.At the same time,Chang’e-4 obtained the day and night temperature of the shallow lunar soil on the back of the moon for the first time.Therefore,a dynamic lunar soil simulant test to simulate the lunar soil was carried out on the earth,and the lunar soil simulant was provided as the test conditions,and the building characteristics of the lunar soil in the future were tested.In this paper,the Nanjing hexahedron basalt with similar composition of lunar soil was used as the experimental material.The dynamic and static mechanical properties of the lunar soil simulant under different negative temperatures and different initial moisture contents and the lunar soil simulant geopolymer under different curing ages and different lime contents were tested.Combined with XRD test and SEM test,the related research on the lunar soil simulant and its geopolymer was carried out from the macro and micro aspects.The main research achievements are as follows:(1)The unconfined compressive strength test of lunar soil simulant under negative temperature(-5°C,-10°C,-15°C and-20°C)and different initial moisture content(5%,8% and 10%)was carried out.The results show that: within the range of the test temperature and initial water content,the unconfined compressive strength of the lunar soil simulant increases with the decrease of temperature under the same initial water content,and the increase decreases gradually;the elastic modulus decreases with the decrease of temperature When the temperature is-10℃,it reaches a peak value and then decreases,and the failure strain shows a trend of "first decrease and then increase" with the decrease of temperature,and the turning point is at-10℃.(2)The unconfined compressive strength tests of lunar soil simulant geopolymer with different curing ages(3d,7d and 28d)and different content of lime(0.5%,2.0%,4.0% and 6.0%)were carried out.The results show that the stress-strain curves of the lunar soil simulant geopolymers are all strain softening in the test,and the compression process is divided into compaction stage,elastic deformation stage,plastic deformation stage,and failure stage.With the increase of curing age,the unconfined compressive strength of lunar soil simulant geopolymer also increases.When slaked lime is not added,the failure types of the samples are mainly conical failure and lateral bulging plastic failure;after adding slaked lime,the failure types of the samples are mainly brittle failure.(3)The SHPB tests of lunar soil simulant and its geopolymer under different impact pressures(0.2 MPa,0.3 MPa and 0.35 MPa)were carried out.According to the test results,the dynamic stress-strain characteristics,failure mode and energy consumption characteristics of lunar soil simulant were analyzed.The results show that within the strain range of strain softening stage,the dynamic compressive strength is positively correlated with the strain rate;The failure strain is greatly affected by the initial moisture content.The failure strain is positively correlated with the initial moisture content when the moisture content is low,and negatively correlated when the moisture content is high;failure types are mainly conical shear failure and granular crushing failure.The SHPB test under impact pressure(0.25MPa)was carried out on the lunar soil simulant polymer with curing age of 28 days.The results show that when the content of lime is less than4%,the sample is broken,and the proportion of small particle size fragments of 0.3mm–0.6mm is high.(4)The energy dissipation law of lunar soil simulants and lunar soil simulant geopolymer under high strain rate is analyzed.At the same temperature and the same initial water content,the fitting curve of the lunar soil simulants absorbed energy and the strain rate showed a linear fitting relationship,that is,with the increase of the strain rate,the lunar soil simulants absorbed energy showed a positive correlation growth.(5)According to the dynamic and static mechanical test results,the representative lunar soil simulant and the lunar soil simulant polymer under different curing ages were selected for XRD test and SEM test.The results show that the addition of lime can effectively improve the internal microstructure,and the hydration products are mainly C-(A)-S-H gel,and the hydration products are dense.The addition of lime improves the compressive properties of polymer in lunar soil simulant.Figure [42] Table [17] Reference [99]...