Study On Corrosion Resistance And Service Characteristics Of Eco-porous Fiber Wool For Sponge City Construction

Owing to the excellent water-permeable function,the eco-porous fiber wool has became a new type of water-permeable material for the construction of sponge cities.In this research,it is of great significance to explore the relationship between the apparent density and acidity coefficient of eco-porous fiber wool on macro-performance and micro-mechanism.Combining with numerical simulation,service characteristics and the service time of eco-porous fiber wool was analyzed and predicted on functionality,safety and durability.The main research contents and results are as follows:（1）Through the indoor simulated rainfall experiment,the performance of water direct contact of eco-porous fiber wool with apparent density of 75kg/m³and 120kg/m³and acidity coefficients of 2.2 and 2.4 was studied.The apparent density had a greater influence on the performance of water direct contact of eco-porous fiber wool.The high-density fiber wool had high porosity,poor water absorption and permeability,but slightly longer water retention time.The effect of acidity coefficient on water contact performance was almost negligible,but it may affect the water absorption and water retention properties of fiber itself.（2）Through the simulated rainfall experiment,the mechanical properties of eco-porous fiber wool with different apparent density and acidity coefficient was studied.The failure modes of eco-porous fiber wool were yield failure or instability failure whose deformation reaches 10%of the total thickness.Apparent density had a greater impact on the compression properties of eco-porous fiber wool.The high-density eco-porous fiber wool was superior to standard-density fiber wool in compression resistance.The advantage of acidity coefficient in the fiber had not yet been revealed.（3）The corrosion resistance of eco-porous fiber wool with different acidity coefficients was studied in acidic rainwater.As the erosion time increases,the surface of eco-porous fiber wool appeared deposits and etchings,and even linear micro-cracks;the diameter of the single fiber decreases,the maximum breaking force decreases,and the tensile strength decreases.The greater the acidity coefficient,the better the appearance and tensile strength of the single fiber,indicating that it was more resistant to acid corrosion.（4）Si⁴⁺、Al³⁺、Ca²⁺、Mg²⁺of eco-porous fiber wool rapidly dissolved within 18 days in the experiment in acid rainwater,and then the dissolution rate slowed down.Si⁴⁺and Al³⁺were difficult to dissolve,and the amount of dissolution was almost the same.Ca²⁺and Mg²⁺were more easily dissolved in acidic media.These ions exchanged with H⁺in the erosion solution,which damaged the network structure of fiber and eventually caused the fiber to fail.The fiber with large acidity coefficient had a more stable network structure.（5）Predicting the compression strength of eco-porous fiber wool with different apparent densities through numerical simulation.Geo Dict software was used to establish a random-growth three-dimensional（3D）model of eco-porous fiber wool,and the compression strength was calculated based on the fast Fourier transform method.The compression strength increased linearly with the increase of apparent density.When subjected to compression stress,the high-strain areas first appeared on the bearing surfaces of the two ends of the fiber model,and the high-stress distribution areas appeared in some fibers inside the porous fiber,which eventually leaded to fiber breakage and failure.（6）By establishing the relationship between eco-porous fiber wool and the performance of water direct contact,compression performance and erosion resistance in different erosion ages,service characteristics and the service time of eco-porous fiber wool was analyzed and predicted on functionality,safety and durability.From the perspective of long-term service,standard-density eco-porous fiber wool was superior to high-density fiber in functionality and high-density fiber wool was superior to standard-density fiber in safety.Eco-porous fiber wool with high acidity coefficient has better durability.Limiting the service life of standard-density eco-porous fiber is compressive strength,and restricting the service time of high-density fiber is water permeability It will provide a reference for the eco-porous fiber wool to serve in the construction of sponge cities.