Study On Iron Tailings Macroporous Permeable Concrete Performance

With the accelerating process of urbanization,more and more pavement is hardened by concrete,cement asphalt and other water blocking materials,forming the ecological "artificial desert".These convenient roads in the human society to bring convenience at the same time,but also because of the water impermeability of these water-blocking materials,to the urban environment caused serious pressure,more and more places frequent urban waterlogging phenomenon.So porous pervious concrete will become a development trend.In this study,the experimental study was conducted to analyze the grain size of the coarse aggregate particles of the ZhaShui tailings,the influence of the mixing ratio of different grain sizes on the porosity,the design of the slurry coating thickness,the properties of permeable concrete with coating thickness.The main research contents and achievements are as follows:(1)Respectively to 9.6 ~ 16.0 mm,16.0 ~ 19.0 mm,19.0 ~ 26.5 mm three fraction of coarse aggregate particles in grain shape research and the mix proportion of different graded aggregate analysis of the influence of the void fraction.The results show that the coarse aggregate particles have a high spherical shape,a higher shape index and a more rounded grain shape.The void ratio calculated by the cube model with equal particle size is 47.6%,that is,the maximum void fraction in the ideal arrangement.The porosity calculated by the particle size cube model is 27.1% and the porosity is reduced by 20.5%.On the basis of the formation of the skeleton with large particle size aggregate particles,the filling is gradually densified with the increase of the number of aggregates,the porosity gradually decreases,and when the mixing ratio of different grain size exceeds 1: 1,the particle interference effect is generated between the aggregates,and the particle interference effect is enhanced and then weakened.(2)Based on parcel layer thickness of porous permeable concrete mixture ratio design as well as to the water cement ratio on the influence of the cement paste wrapped layer thickness is analyzed.The test data show that with the increasing of water cement ratio,cement paste viscosity value decreases continuously,cement paste with the increase of viscosity,fluidity and decreases;Under the condition of the aggregate particle size must be,as the water slurry viscosity increases gradually,the aggregate surface water slurry showed a trend of gradual thickening of the parcel layer thickness,layer thickness and when design package,water slurry viscosity is constant,the aggregate particle size,the greater the aggregate surface actual package the thicker the thickness of cement paste.(3)Based on the model of particle size spheroidal accumulation,a single particle size of 9.5 ~ 16.0mm was selected to establish the porous water permeable concrete model,to verify the reliability of the model and the influence of different coating thickness on the coagulation performance.The data show that The porosity calculated by the model is close to the porosity measured by the test.With the increasing thickness of the coating layer,the plane porosity and the permeability coefficient tend to decrease,and with the increase of the thickness of the coating layer.The compressive strength and the flexural strength of 7d and 28 d were increased first and then decreased.The plane porosity,volume porosity and water permeability coefficient of single grain grade increased with the increase of aggregate size.When mixed with different mixing ratios,it is expressed as a base that forms a skeleton with large particle size aggregate particles.On the basis of the increase in the number of particles with small particles,the porosity,volume porosity,permeability coefficient and tortuosity are gradually reduced.The compressive strength of the single-stage permeable concrete decreases with the increase of the particle size,and the strength of the permeated concrete during mixing is between the maximum and the minimum of the permeable concrete strength.Basalt fiber and stone powder on the permeable concrete has a significant enhancement.(4)Using CT images and then three-dimensional reconstruction analysis of flow curves of water molecules,using the Mimics17.0 software test showed that: with the gradual increase of the proportion of the aggregate particle size,water molecules via the path is tortuous,namely Le1< Le2< Le3< Le4,Calculation of tortuosity value is increasing gradually,namely 1< 2< 3< 4.(5)Before will be enhanced and enhance antifreeze experiment was carried out respectively,and the block as a contrast test results show that the method of the permeable concrete bibulous rate is low,and after 15?30?50 times of freeze-thaw cycle of quality and strength loss in the range of specification;After 14 d and 28 d days to simulate the rains washed out after test and different PH value oxalic acid erosion test after the quality and strength loss also meet specification requirements.