Research On Mechanical Properties And Anti-penetration Simulation Of Ceramic Ball Coarse Aggregated Ultra-high Performance Geopolymer Concrete

This study intended to study the effects of ceramic ball particle size(3 mm,6 mm,and10 mm),ceramic ball content(0,10 vol%,20 vol%,and 30 vol%),and steel fiber content(0,0.6 vol%,1.2 vol%,and 1.8 vol%)on the workability,deformation properties,uniaxial compressive and flexural properties of UHPGC by adding medium-aluminum ceramic balls as coarse aggregates on the basis of UHPGC.Then,combined with scanning electron microscopy(SEM)for microscopic morphology observation,the influence of the above parameters on the mechanical properties of UHPGC was discussed and analyzed.Finally,finite element(FE)and smooth particle hydrodynamics(SPH)methods were used to numerically study the dynamic response of UHPGC targets containing ceramic balls under projectile penetration,and the results were verified with experimental results.The main contents and conclusions of this study were summarized as follows:(1)The effects of ceramic balls and steel fibers on the spread of UHPGC were studied.The results showed that within the range of 0-1.8 vol% steel fiber content,the workability of UHPGC decreased with the increase of steel fiber content.When the steel fiber content was1.2 vol%,the workability of UHPGC decreased with the increase of ceramic ball size(3mm-10 mm);With the increase of the content of ceramic balls(0-30 vol%),the workability of UHPGC showed a decreasing trend.(2)The influence of ceramic balls and steel fibers on the uniaxial compressive performance of UHPGC was studied.The results showed that the compressive strength of UHPGC increased with the increase of steel fiber content in the sample without ceramic balls;In the sample containing 20 vol-% 6 mm ceramic balls,UHPGC mixed with 0.6 vol-% steel fibers was a maximum compressive strength of 176.8 MPa,and as the steel fiber content continued to increase,the compressive strength of UHPGC gradually decreased;In addition,the UHPGC containing 1.2 vol-% steel fiber has a high compressive strength when the size of ceramic ball was 3 mm-6 mm and the content of ceramic ball was 10 vol-%-20 vol-%,and the compressive strength will be limited to decrease with the increase of the size of ceramic ball or the content of steel fibers.(3)The influence of ceramic ball and steel fibers on the flexural performance of UHPGC was investigated.The results showed that in UHPGC without ceramic ball coarse aggregate,the matrix flexural strength increased with the increase of steel fiber content.In the UHPGC with 20 vol-% 6 mm ceramic balls,the UHPGC with the steel fiber content of 0.6vol-%-1.2 vol-% showed better bending resistance.When the steel fiber content was 1.2vol-% and the ceramic ball content is 20 vol-%,with the increase of ceramic ball size(3mm-10 mm),the UHPGC flexural strength first increases and then tends to be stable.In addition,the toughness of UHPGC was studied through the load-deflection curve,and it was found that the steel fiber can effectively enhance the toughness of the matrix,while the increase in the particle size or content of ceramic ball will effectively reduce the toughness.(4)The K&C concrete dynamic material constitutive model was used to simulate the dynamic response of the UHPGC target containing ceramic ball coarse aggregate under the penetration of the projectile at the macro level.By comparing the two numerical simulation methods of FE and SPH,it is found that the simulation results of the SPH method are closer to the experimental data.