Experimental Study On Durability And Plant Growth Performance Of Macroporous Pervious Concrete

Due to the impermeability of traditional slope protection materials,the original vegetation layer is damaged,and the slope is lack of vitality,which is not conducive to ecological construction.As a slope protection material,macroporous pervious concrete has good permeability and permeability.Plants can be planted by using the internal high porosity,which has the function of soil consolidation and ecological protection.In this paper,geogrid is added into the permeable concrete with large pore.The purpose is to use geogrid as reinforcement material to ensure the integrity of concrete,make the concrete broken and not broken,and extend the life of the project.The volume method is used to design the concrete mix proportion.Through orthogonal test,the influence of coarse aggregate,water cement ratio and water consumption on the compressive strength,permeability coefficient,connected porosity and grouting area ratio of large porous permeable concrete is discussed.The best mix proportion design scheme is selected,and the grass planting test is carried out on the formed concrete plate.Based on the analysis of the test results,the following conclusions are drawn:（1）The orthogonal test results show that the strength of macroporous pervious concrete increases slightly and the connected porosity decreases by 3%after adding geogrid;Aggregate gradation and water consumption are the main factors affecting the connectivity porosity and permeability coefficient of macroporous pervious concrete;Regression analysis shows that the compressive strength has a negative linear relationship with the connected porosity,and the linear regression formula is y=55.359-4.272x,R²=0.96;When coarse aggregate is crushed stone with gradation of 10-20 mm,water consumption is 60 kg/m³,water cement ratio is 0.35 and geogrid is plastic grid,the connected porosity can reach 33%,permeability coefficient is 19.69mm/s,grouting area ratio is 0（no grouting）and compressive strength is 6.0 MPa.These performance indicators can fully meet the needs of vegetation growth.（2）The slow freeze-thaw cycle test results show that the macroporous permeable concrete can withstand about 40 freeze-thaw cycles before failure.The smaller the water cement ratio is,the smaller the connected porosity is,the better the frost resistance is.The addition of geogrid has little effect on the frost resistance,but the geogrid plays a role of"disconnection"after the freeze-thaw fracture of the specimen,which makes the macroporous permeable concrete block maintain integrity.（3）The results of alkali reducing test show that the PH value in concrete pores can be reduced from 11.82 to 8.5 by replacing 4%of water consumption with Fe SO₄.The maximum adaptive PH value of alkali resistant plants selected in this paper is 9,and the alkali reducing measures can meet the growth needs of plants.（4）The macroporous permeable concrete plate specimens with the length of30cm,the width of 20cm and the height of 7cm were made for the plant growth test,three kinds of plants,tall fescue,ryegrass and Setaria,were selected for planting.The results showed that the plants could grow normally on the concrete,and the average growth height of the plants was 18 cm in 30 days.After 60 days,the roots of the three plants can take root in the concrete,and the rhizome of ryegrass can penetrate the concrete and take root in the subsoil.In conclusion,macroporous pervious concrete has good plant growth performance.The addition of geogrid not only ensures the original strength and connected porosity,but also increases the integrity of macroporous pervious concrete,which can be considered to be applied in slope and bank protection engineering and soil erosion control engineering.