| Compared with the traditional concrete revetment,porous vegetation concrete has the characteristics of flood control,ecology and landscape,and is widely used in river treatment projects.The pore mesostructure of porous vegetation concrete is one of the main factors affecting plant growth.The traditional research methods of pore mesostructure are greatly affected by human intervention,and the acquisition of experimental data is limited.At the same time,the high alkaline environment in the hole of planting grass concrete is also one of the main factors affecting the growth of herbaceous plants,and the effective improvement of alkaline environment in the hole is particularly critical.Therefore,it is necessary to analyze the micro structure of porous vegetation concrete and improve the alkaline environment in the pore.In this paper,CT scanner is used to scan the porous vegetation concrete specimens with different mix proportions,reconstruct the three-dimensional model of porous vegetation concrete,explore the characterization parameter characteristics of its pore mesostructure,creatively enrich the means of obtaining the pore microstructure of porous vegetation concrete,and provide a new way for the study of porous vegetation concrete pore structure in meso scale Soil alkaline improvement test,comparative analysis of porous vegetation concrete hole alkaline environment improvement measures;carry out planting test,reveal the impact of grass concrete on the stems and leaves and roots of herbaceous plants.The specific conclusions are as follows:(1)The 3D visual simulation model is established by using CT scanning technology.The target porosity and actual effective porosity are taken as the main calibration indexes,which effectively improves the accuracy of 3D simulation model.The calculated results of porosity of 3D model are slightly less than that of test method,and the error is between 0.6% and 2.4%,and it is closer to the design value.(2)Based on the analysis of the micro structure parameters of porous vegetation concrete,the two-dimensional pore number,porosity,pore size distribution,threedimensional tortuosity and fractal dimension of the specimens were quantitatively obtained.The results show that the water cement ratio has a great influence on the total number of pores in concrete,and the larger the water cement ratio is,the smaller the number of pores is;the tortuosity in the pores of porous vegetation concrete is negatively correlated with the target porosity,and the fractal dimension of pore structure in concrete is positively correlated with the target porosity,that is,the larger the target porosity and the smaller the water cement ratio,the more favorable the micro structure of concrete pores is The roots of herbaceous plants grow.(3)The pH value of the sample decreased by 0.5 ～ 1.With the increase of mineral admixture,the pH value of the sample decreased,and the effect of silica fume was the best.The pH value of epoxy coating can be decreased by spraying epoxy resin with the pH value of 2.5.The results show that the order of alkaline environment improvement effect of porous vegetation concrete is: Superphosphate > boric acid > ammonium dihydrogen phosphate > potassium dihydrogen phosphate > ferrous sulfate > untreated.(4)By analyzing the growth of herbaceous plant stem and leaf,it was found that the thickness of test block had the greatest influence on the growth of herbaceous plant stem and leaf.Under the same growth condition,the growth height of herbaceous plant decreased with the increase of sample thickness.The root architecture parameters showed that the root system was greatly affected by the porosity.With the increase of porosity,the root growth was better,which verified the conclusion of pore microstructure analysis. |
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