| Eco concrete has been widely applied to slope protection engineering due to its functions of water permeability,vegetation growth and water purification.Its durability has been tested in the face of freeze-thaw damage and erosion.Supported by National Natural Science Fund Project“research on current scouring experiment and damage mechanism of porous ecological concrete under the erosion environment based on freeze-thaw cycles and sulfate attack(project number:51608235)",key development plan of Zhenjiang in 2015“design and application of intelligent system for rainwater reuse in artificial wetland(project number:SH2015004)”and project of autonomous science and technology of North control water affairs“Application of layered double hydroxides modified eco concrete in constructed wetland(project number:ZZLX-2017-12),based on existing theories and research foundations,the erosion tests of ecological concrete under the action of freezing thawing cycle,moving water scour and alternation of two factors are carried out in this paper.A life prediction model for freezing thawing damage is established and the reliability of the model is verified.It provides reference for the mix design and engineering application in the future.1.Introduce the composition of ecological concrete and the selection requirements of raw materials.Put forward the mix proportion design method and preparation process.Determine the mix proportion of different aggregate sizes of eco concrete.Test the cement paste fluidity,porosity and compressive strength.2.Carry out the freeze-thaw cycle test of three kinds of eco concrete blocks by quick freezing method.Explore the relationship between the macroscopic mechanical properties and the number of freezing and thawing cycles.Observe the failure phenomena of the specimen and investigate the mechanism of the freezing and thawing damage.The experimental results show that the quality,the relative dynamic elastic modulus and the compressive strength of the ecological concrete decrease with the increase of the freezing and thawing cycles.The speed of freezing thawing damage of ecological concrete is faster than that of ordinary concrete,mainly because the pore size of the inner connected pores is much larger than that of the fine pores in the cement stone,which bears greater expansion pressure and seepage pressure.The life prediction model of freeze-thaw damage is established.It is predicted that the final freezing and thawing cycle of the ecological concrete test block is 38 times,which is in agreement with the test value.3.Carried out the scouring test of three kinds of ecological concrete(3?7 mm,5?16.5 mm,16.5?31.5 mm)by underwater steel ball method.Explore the change of wear rate and scour strength with the flushing time and the effect of aggregate size.The anti scouring performance of ecological concrete is higher than that of ordinary concrete.The greater the size of the aggregate,the better the resistance to scour.The proper adjustment of the aggregate size can improve the strength of the abrasion resistance,but the content of the fine bone and cement should also be paid attention to.The erosion test on the alternating action of freezing thawing cycle and moving water scour on the ecological concrete is compared with the single factor test.It is found that the effect of alternating action on the ecological concrete is greater,mainly because the cement slurry between the aggregate under the action of freezing and thawing is damaged by the expansion stress and the seepage pressure.With the scouring of water,the cement slurry between the aggregate is more likely to fall off,and the coarse aggregate loses its cohesive force and the whole block falls off. |
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