Research Of Coal-Based Solid Waste Permeable Pavement Brick At Low Temperature

As a new green building material,the solid waste base permeable pavement brick is not only friendly to the environment,but also meets the needs of the construction and development of the"sponge city".It conforms to the national concept of sustainable development,because of its good environmental protection ability,excellent permeability and permeability,good sound absorption and noise reduction performance.The decorative effect is in line with popular aesthetics,and the rate of return on investment is high,so the future development prospect of solid waste water permeable pavement brick is very broad.The solid waste base sintered pavement brick is made of high temperature sintering with solid industrial waste,such as fly ash and coal gangue,and the recycling of industrial waste is realized.However,there are still many problems,such as high energy consumption,high cost,poor wear resistance,easy breaking and poor freezing and thawing performance.This is limited to a certain extent.The promotion and use of the surface brick with permeable road.Therefore,this paper studies the solid waste base permeable pavement brick from several aspects such as raw material formula,processing technology and sintering conditions,aiming to burn out the solid waste base permeable pavement brick with low energy consumption,excellent performance and good resistance to freezing and thawing in order to promote the popularization and application of the permeable pavement brick in the north area.This subject is based on R₂O-RO-Al₂O₃-SiO₂-B₂O₃ system of fritted glaze,developed the high strength low temperature glaze formula.Using the glazed pulp to cover the fly ash ceramsite as the base material,the waste refractory particles are coated with the glaze pulp as the surface material,and the solid core ceramic tile is prepared by filling the solid core ceramic brick frame with the layer of layer material.The melting temperature of different glaze formulations was tested,and the preparation of glaze formulations at low temperature was explained by"quasi non reactive"sintering mechanism.The effects of the particle size,sintering temperature,heat preservation time,molding pressure and the amount of glaze on the permeability and compressive properties of the solid waste base permeable brick are discussed.The optimum technological conditions for the preparation of the solid waste base permeable pavement brick are obtained by the orthogonal experiment.Moreover,the freeze-thaw properties of permeable bricks were explored,and the mechanism of freezing and thawing was analyzed.The conclusions are as follows:（1）Using kaolin,quartz,boric acid,borax,strontium carbonate,calcium carbonate,potassium carbonate,zinc oxide as the main raw material,kaolin/quartz,boric acid,calcium carbonate,potassium carbonate raw material as a benchmark,using L9（3⁴）4 factors 3 levels orthogonal experiments,through the comprehensive evaluation method on the comparison to glaze and ratings,choose the good wear-resisting performance,strong structural mechanics performance of glaze formula.Within the scope of this study,the research shows that influence the properties of glaze is primary and secondary order（main）kaolin/quartz>CaCO₃>boric acid>K₂CO₃（second）,the highest score is number 6 glaze formula,melting temperature is 865℃,at this time Al₂O₃ 7.94%,SiO₂54.08%,B₂O₃ 9.65%,Zn O 1.96%,CaO 10.46%,K₂O 6.05%,Na₂O1.61%,SrO 8.25%,the optimal formula of vickers hardness is 6815 MPa,the flexural strength of 71 MPa.（2）The melting temperature of the 9 glaze formulations is below900℃,which significantly reduces the sintering temperature of glazes,and meets the requirements of low temperature sintering.Mainly using"quasi non reactive"sintering mechanism to reduce the sintering temperature of the glaze,that is,the addition of low melting point material borax and other low temperature solvents in the glaze,the glaze will produce liquid phase in the melting range of low melting point material,which will help the solid phase participate in the sintering reaction and reduce the melting temperature of the glaze.（3）The waste refractory material is selected as the surface material,fix the preparation conditions of the base material,and put the base material and the surface material into the ceramic tile frame,with the decrease of the particle size of the abandoned refractory,the increase of the molding pressure and the increase of the glaze of the high temperature binder,the permeability of the surface brick sample will decrease,but the compressive strength will be improved to a certain extent.The higher the sintering temperature and the longer the holding time,the permeability coefficient of the permeable brick increases first and then decreases,while the compressive strength keeps increasing.The results show that:with the decrease of particle size,the increase of molding pressure,the increase of firing temperature and the increase of high-temperature binder glaze,the compressive strength of surface material is improved,but the permeability of water will decrease.The optimum processl conditions are as follows:The particle size is 0.45-1.25 mm,the molding pressure is 20 MPa,the firing temperature is 950℃,the amount of glaze is added 7.5%,at this time,the permeable property of the solid base permeable pavement brick is 4.92×10^-22 cm/s,that the compressive strength is 41.40 MPa.（4）Freeze-thaw damage mechanism of samples of solid waste permeable pavement bricks obtained from the Institute.That is,the water in the internal voids of the material will be affected so that the volume of ice builds up,so that the water that has not frozen will migrate into other pores,and in the process,it will encounter resistance and form hydrostatic pressure.When this pressure exceeds,the material will expand.At the critical pressure,the material is destroyed.（5）To investigate the effect of solid medium permeable pavers after freeze-thaw structure and performance change after the experiment.The research shows that after 50 freeze-thaw cycles,the strength of solid base permeable pavement brick is decreasing,but the strength loss rate is under10%.Some glazes on the surface of filled particles appear cracks,but most of them have intact glaze.Besides,the greater the porosity is,the higher the strength loss rate of the permeable pavement brick is.