| The lightweighting of concrete is an inevitable requirement for building development.At the same time,green building materials are of great significance for energy saving and environmental protection.Replacing the natural river sand stones in concrete aggregates with lightweight high-strength aggregates is an inevitable trend in the development of green lightweight concrete..The existing lightweight concrete has the problems of low strength,excessive water absorption and insufficient fluidity.In this paper,based on cement mortar with water-cement ratio of 0.45 and sand rate of 50%,the volume of fly ash float beads recovered by power plants is replaced with 10%,20%,30%,and 40%sand to make float bead cement mortar(CsXX)Cube-shaped compression test piece,rectangular parallelepiped bending test piece and small cylindrical impact test piece,after curing and curing,use a digital pressure testing machine to perform a 3 day、7 day、28 day compression and bending test on the test piece,and measure For the physical properties of the 28-day test piece,three sets of dynamic shock compression tests with different strain rates were performed on the test piece using Hopkinson pressure rod equipment.The test results were processed by the "two-wave method" to obtain the stress-strain relationship curve and energy absorption during the test.The curve and analysis of the test data show the effect of the amount of floating beads on the physical properties,static mechanics and dynamic mechanics of the cement mortar specimen.The test results show that:(1)The floating beads greatly reduce the structural weight of the cement mortar specimens.The average apparent density of the Cs40 group specimens is reduced by 15.4%compared with the control group Cs0,and the average water absorption rate is increased by 25.45%.(2)The static mechanical strength of the bleaching bead cement mortar specimens at various ages showed a downward trend with the increase of the bleaching bead content.The 28-day average compressive strength and average flexural strength of the test group Cs40 specimens were 40.39MPa,2.19MPa Cs0 decreased 16.3%and 14.6%compared with the control group.(3)With the increase of the amount of bleaching beads,the dynamic peak stress of the bleaching bead cement mortar specimen decreases and the peak strain increases.When the strain rates were 74.2s-1,84.9 s-1 and 95.1 s-1,the peak stress of the Cs40 group specimens was reduced by 9%,6.8%and 6.9%compared to the Cs0 group specimens,respectively.When the strain rates were 84.9 s-1 and 95.1 s-1,the peak strain of the Cs40 group increased by nearly 100%compared with the CsO group.When the amount of floating beads is constant,with the increase of the strain rate,the peak stress of the test pieces of each test group increases,the peak strain decreases,and the material shows a strong sensitivity to strain rate.In general,the DIF and energy dissipation density SEA of the floating bead cement mortar specimens showed an increasing trend with the increase of the floating bead content and strain rate.(4)The results of the numerical simulation are highly consistent with the experimental results,demonstrating the feasibility and accuracy of the numerical simulation used to describe the dynamic response of the lightweight floating bead cement mortar.At the same time,the numerical simulation reproduces the dynamic fracture process of cement mortar under high strain rate,showing typical brittle splitting and shear failure.The research on the performance of lightweight concrete cannot only be in the field of static mechanics,but also on the research of dynamic mechanical properties.This article provides a new idea for the research of light aggregates by replacing the sand with bleaching beads as the structural lightweight aggregate.Simultaneous static and dynamic mechanical tests are carried out on the bleaching bead cement mortar to study its comprehensive mechanical properties in depth,which is The research work provides a theoretical basis.Figure [31] Table[ 13] References[ 93]... |
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