Mswifa-Fly Ash-Slag Ternary Geopolymer From Municipal Solid Waste Incineration Slag

A large amount of toxic and harmful incineration fly ash is produced after domestic waste incineration,and Geopolymer solidification method is considered to be an effective harmless disposal method of waste incineration fly ash.MSWIFA contains a certain amount of Si,Al and Ca elements,which can theoretically be used as Geopolymer Materials.However,the geopolymer prepared from waste incineration fly ash will cause problems such as expansion and insufficient compressive strength,resulting in poor utilization effect of Fly Ash Geopolymer.In this paper,fly ash,slag and waste incineration fly ash are used to prepare ternary geopolymer,which can be used as building materials to provide a way for the resource treatment of fly ash.In this paper,alkali melting pretreatment technology was used to improve the reactivity of MSWIFA and eliminate the swelling of geopolymer prepared from MSWIFA;The ternary geopolymer was prepared by alkali melting pretreatment of MSWIFA,fly ash and slag.The effects of MSWIFA content,alkali activator and curing system on the properties of the ternary geopolymer were studied.The phase composition of the geopolymer was analyzed by XRD and the morphology of the geopolymer was analyzed by SEM.The acetic acid buffer solution method was used to detect the leaching concentration of heavy metals in ternary geopolymer,analyze the solidification effect of ternary geopolymer on heavy metals in waste fly ash,and prepare ternary geopolymer mortar to analyze its application effect.The contents and conclusions of the study are as follows:1.the alkali melting pretreatment technology is adopted to improve the reactivity of MSWIFA and eliminate the polymer expansion phenomenon of MSWIFA preparation.The results show that the compressive strength of geopolymer increases with the increase of MSWIFA melting temperature.In high temperature environment,Al in MSWIFA reacts with Cao to form Ca（Al O₂）₂,which eliminates the elemental Al in MSWIFA and solves the swelling phenomenon of geopolymer.The compressive strength of geopolymer first increases and then decreases with the increase of Na OH addition ratio.Alkali melting pretreatment can improve the silicon aluminum solubility of fly ash and the reactivity of MSWIFA.2.on the basis of alkali melting pretreatment of MSWIFA the effects of MSWIFA content and alkali activator on the properties of ternary geopolymers were studied.The results show that the compressive strength of geopolymer decreases with the increase of MSWIFA content,and the setting time and consistency of geopolymer increase with the increase of MSWIFA content.SEM and XRD analysis show that with the increase of MSWIFA content,the content of Si and Al in geopolymer decreases,the C-S-H gel decreases,and the compressive strength of geopolymer decreases.The compressive strength and setting time of geopolymer first increased and then decreased with the increase of Na OH concentration,and the consistency of geopolymer decreased with the increase of Na OH concentration;The setting time,consistency and compressive strength of geopolymer first increased and then decreased with the increase of the ratio of Na₂Si O₃ to Na OH;The setting time and consistency of geopolymer increase with the increase of liquid-solid ratio,and the compressive strength of geopolymer decreases with the increase of liquid-solid ratio.3.based on the study of the preparation parameters of ternary geopolymer,the effects of curing time and curing temperature on the compressive strength of ternary geopolymer were studied.The results show that the compressive strength of geopolymer increases with the increase of curing time;The compressive strength of geopolymer increases with the increase of curing temperature,but the compressive strength of geopolymer decreases when the curing temperature exceeds 90℃.4.the acetic acid buffer solution method was used to detect the leaching concentration of CD,Cu,Pb and Zn in the ternary geopolymer,which showed that the geopolymer had a good curing effect on the heavy metals Cd,Cu,Pb and Zn in fly ash.The prepared geopolymer mortar has good performance and heavy metal curing effect.