Preparation And Properties Of Solid Waste Foundation Sintered Permeable Brick

With the acceleration of urbanization in China,the proportion of impervious areas on the surface of the city has greatly increased,which has brought a huge negative impact on the urban environment and people's lives.The construction of sponge cities is imminent.As a new type of green building materials,the“spongy”pavement permeable bricks can effectively absorb osmotic rainwater,supplement groundwater resources,and fully alleviate the phenomenon of“urban heat island effect”and“city-viewing sea”due to its excellent water-storage performance.This paper studies the preparation technology of permeable pavement brick that a kind of refractory waste as the surface material,the fly ash ceramsite as basic material,using self-made R₂O-RO-Al₂O₃-Si O₂-B₂O₃ is glaze of binder,by adopting hierarchical cloth,static pressure molding process,the particle stacking method of pore-forming sintering.Through melting temperature test,flexural strength test,hardness test and XRD and SEM analysis methods,optimized low-temperature high-strength binder formulations and studied the influence of process conditions on the main properties of the sintered brick,such as compressive strength,permeability,and frost resistance.In addition,this paper analyzed the mechanism of anti-freezing and thawing property of sintered permeable brick.Research indicates:?1?Kaolin,quartz,boric acid,borax,calcium carbonate,sodium carbonate,magnesium oxide,potassium carbonate as the main raw material,can produce excellent performance of R₂O-RO-Al₂O₃-SiO₂-B₂O₃series of low temperature high-strength binders:Kaolin 8.83%,Quartz40.38%,Borax 22.06%,Potassium carbonate 4.73%,Sodium carbonate2.13%,Calcium carbonate 18.66%,Magnesium oxide 3.22%for the formulation,the flexural strength can reach 76.03MPa and the melting temperature is 830?.Kaolin 13.46%,Quartz 34.96%,borax 22.42%,Potassium carbonate 3.60%,Sodium carbonate 4.96%,Calcium carbonate18.96%,Magnesium oxide 1.63%for the formula,Vickers hardness can reach 7208MPa,the melting temperature is 830?.?2?The effect of the main oxides of conventional glazes on the properties of binders was investigated.Among them,the significant relationship between the intensity effect was:B₂O₃>CaO>SiO₂>MgO>Al₂O₃>Na₂O>K₂O;The significant relationship between the hardness effect is:CaO>SiO₂>K₂O>Al₂O₃>Na₂O>MgO>B₂O₃.The content of CaO and Si O₂ has a significant influence on the bending strength and the surface Vickers hardness of the binder.Whether or not the crystal is produced is an important factor in the performance of the binder.The formation of CaSiO₃crystal is beneficial to the improvement of bond strength and hardness,and the glass phase and CaSiO₃ crystals wrapped and combined,CaSi O₃ plays the role of microcrystalline glass,have a positive impact on the performance of the binder.?3?In this paper,when the particle size of the abandoned refractories is large,reducing the particle size of the aggregate can significantly increase the strength of the surface layer material,and has little effect on the permeability of the surface layer;the increase in the amount of binder also played a role in strengthening the strength,but too much will block the pores and affect the permeability of the water;the forming pressure in the range of 15-30MPa,the compressive strength increases and the trend of the decline of the permeability coefficient is relatively flat;the firing temperature is largely affected by the initial melting temperature of the binder,and the firing temperature is too high.On the one hand,the molten glass phase is too much,and on the other hand,the binding fluidity is too strong,deposition to the bottom under the influence of gravity has a negative effect on the performance of the permeable brick.?4?When the waste refractory material is used as the surface layer material,the best process conditions for preparing the sintered brick are:particle size range 1.11-1.72mm,binder content 9%,molding pressure20MPa,sintering temperature 850°C,heat preservation time 1h.The compressive strength of the prepared permeable bricks is 42.5 MPa,and the water permeability coefficient is 2.32×10^-2cm/s.Its performance reaches the requirements of the national standard GB/T 25993-2010?Standards for Permeable Pavement Bricks and Pervious Pavement Panels?.?5?The preliminary analysis explored the freeze-thaw damage mechanism of sintered bricks.and the main factors affecting the resistance to freezing and thawing are water saturation,porosity and pore structure.The porosity is also an important factor affecting the strength and permeability of the sintered brick.After 25 cycles of freezing and thawing cycles,the permeable bricks prepared using the optimal conditions have a maximum strength loss rate of 8.94%and a minimum of 7.49%,which is lower than the required 20%of the national standard GB/T 25993-2010?Permeable Pavement Bricks and Pervious Pavement Panel Standards?.