Research And Preparation Of Permeable Pavement Brick Based On Microbial Mineralization Of Steel Slag

The recycling rate of steel slag and carbon dioxide resources in China is low,and the continuous decline of groundwater level has caused the problem of urban drainage to become increasingly prominent.In this essay,steel slag micropowder and coarse aggregate,preferred ratio and molding process,pretreatment measures,abandoning traditional cement,accelerating carbonization under microbial enzymatic reaction to achieve cementation,and preparing permeable paving brick with good engineering performance,stability Good sex and significant environmental benefits.In this essay,the method of calcium source supply is firstly distinguished.The three carbonization systems of pure steel slag,calcium hydroxide-steel slag and dilute acetic acid-steel slag are compared.The orthogonal design is used to evaluate the splitting tensile strength,water permeability and measured porosity.The parameters optimally determined the optimal mixture ratio of the three systems,and further explored the carbonization mechanism under different calcium source systems.It was found that the effective porosity of the calcium hydroxide-steel slag system was significantly reduced,and the same ratio of hydrogenation was carried out.The higher the calcium content,the less the steel slag pulp,and the path for carbon dioxide transport is further reduced,and the carbonization depth is much lower than the carbonization depth of the dilute acetic acid system.The interface between the carbonized steel slag bricks under different calcium source systems shows that the elastic modulus and hardness of the dilute acetic acid-steel slag system are 207%and 298%higher than the elastic modulus and hardness of the calcium hydroxide-steel slag system,respectively.The depth decreases as the amount of microorganisms first increases and then decreases.Therefore,it is recommended to use a dilute acetic acid-steel slag system.The concentration of dilute acetic acid is 0.5 mol/L,the microbial content is 1%,and the stirring method is a gelling material.Secondly,the paper explores the effect of moisture content on the carbonization effect of steel slag pavement.It is found that when the residual water-cement ratio is 0.15,the voids and capillary pores of the brick body are gradually connected to the waterless state,which is conducive to the diffusion and transmission of CO₂.On the other hand,leaving part of the water is beneficial to the microbial acceleration of CO₂ hydration.It is also beneficial to the carbonization reaction of the dissolution of calcium and magnesium ions.At this time,when the two reach equilibrium,the carbonization reaction proceeds rapidly,and a large amount of calcium carbonate is compacted to make the brick body obtain higher strength.The essay also studied the effect of carbonization pressure on the carbonization effect of steel slag pavement bricks.It was found that the strength increased rapidly with the increase of pressure under the negative pressure state,while the strength growth slowed down under the positive pressure state and hardly changed.When the carbonization pressure is 0 MPa,the strength reaches 3.81 MPa,which is 4%lower than the carbonization pressure of 0.3 MPa,and the curing cost is reduced by 70%,which has significant economic benefits.Finally,the microbial mineralized steel slag permeable paving brick was successfully prepared under the optimal system,mix ratio and process parameters,and its basic mechanical properties,durability and water permeability were tested.The compressive strength was 22.48MPa,and the flexural strength was obtained.6.48MPa,splitting tensile strength 3.98MPa,water permeability coefficient 0.206cm/s,reaching the"GB/T 25993-2010 permeable paver and permeable pavement panel"in fts3.5,Rf4.5 A class of permeable paving slabs.