Waste Incineration Fly Ash-waste Glass Geopolymer Mortar Preparation And Performance Studies

The waste incineration fly ash contains heavy metals and toxic and harmful substances,relevant laws in my country stipulate that waste incineration fly ash needs to be harmlessly disposed of.A large amount of waste glass is produced every year,and it is an urgent problem to improve the recycling rate of waste glass.The waste incineration fly ash geopolymer prepared by alkali excitation technology has the characteristics of green environmental protection and good engineering performance.In building materials,glass particles have been proven to replace natural sand as a fine aggregate for mortar.Based on this,geopolymer mortar is prepared with waste incineration fly ash as cementing material and waste glass as fine aggregate;a new method is provided for the co-processing of waste incineration fly ash and waste glass.It has positive effect on waste treatment and environmental safety.In this paper,in order to realize the harmless and recycling of waste incineration fly ash,the recycling of waste glass.Using waste incineration fly ash,glass particles and fly ash as the main raw materials,the geopolymer masonry mortar was prepared by alkali excitation.Preliminary determination of the mixing ratio of geopolymer slurry was carried out by single factor experiment.On this basis,the mixing ratio of geopolymer masonry mortar was optimized by orthogonal design,and the basic properties of the mortar were analyzed and studied.Finally,the geopolymer masonry mortar was characterized and analyzed from the microscopic test(XRD,SEM),and the mechanism of the change of mortar strength and the solidification of heavy metals was revealed.(1)In the geopolymer pulp test,the effect of waste incineration fly ash content,liquidsolid ratio,Na OH concentration,and alkali-liquid ratio on the early compressive strength and coagulation time of the pulp was studied.The results show that the fly ash mixing content is30%,the liquid-solid ratio is 0.5,the concentration of Na OH is 12mol/L,and the alkali-liquid ratio is 3.0,the comprehensive performance of the prepared geopolymer is the best,and the 3d compressive strength can reach 4.9 MPa,the initial setting time is 70 min,and the final setting time is 112 min.The swelling phenomenon of waste incineration fly ash participating in geopolymerization can be eliminated by soaking in weak alkaline solution.Compared to raw ash,there is no obvious difference in the characteristics of the pretreated fly ash,and the pretreated fly ash significantly prolongs the initial setting of the slurry.time.The larger the amount of waste incineration fly ash and the larger the lye-to-liquid ratio,the shorter the setting time,the higher the liquid-solid ratio and the Na OH concentration,and the longer the geopolymer setting time.(2)In the orthogonal test of geopolymer masonry mortar,the effects of glass particle content,Na OH concentration,lye ratio,and liquid-solid ratio on the compressive strength,consistency and water retention of geopolymer masonry mortar were studied.Get the primary and secondary relationship affected by factors;at the same time,the expansion rate of mortar alkali silicic acid reaction is tested.The results show that: when glass particle content is 30%,the concentration of Na OH is 12mol/L,the ratio of alkali to liquid is 2.5,and the ratio of liquid to solid is 0.47,the comprehensive performance of geopolymer masonry mortar is the best,and the consistency and water retention meet the requirements of the specification.Age compressive strength can reach 24.3MPa.The glass particle content has a significant effect on the later strength of the masonry mortar,the liquid-solid ratio has a great effect on the consistency,and all factors have little impact on water retention.When the content of glass particles increases,the expansion rate of mortar increases,but all are lower than the specification limit of 0.1%,indicating that there is no expansion damage caused by alkali silicic acid reaction.(3)Heavy metal leaching in net slurry and mortar is less toxic,and the leaching concentration is far lower than the national standard limit;The waste incineration fly ash harmless,high environmental safety;Geopolymer net mortar and geopolymer masonry mortar have outstanding curing effect on Cd heavy metal,and their curing efficiency is over 99%.(4)The physical phase and microscopic morphology of geopolymer masonry mortar were analyzed by XRD test and SEM-EDS test to reveal the stabilization mechanism of mortar.The XRD test shows that: when the glass particles increase from 0% to 30%,no new phase is formed in the mortar,but the amount of CSH gel and NASH gel increases,and the generated geopolymer increases,which can adsorb more heavy metals;SEM-EDS test It shows that: after adding glass particles,the voids on the surface of the mortar are filled and become more flat and compact,and the encapsulation of heavy metals is better,favoring the enhancement of strength.