为解决传统水泥基注浆材料成本高、能耗和污染大等问题,基于固废材料协同效应,以CFB粉煤灰(CFBFA)、钢渣微粉(SS)、高炉矿渣(BFS)和脱硫石膏(FGD)为原材料制备新型绿色环保的公路路基及桥隧下伏采空区全固废注浆材料.通过系列室内试验,研究了不同CFBFA掺量(80％、60％、50％、40％、20％)、水固比(1∶1.3、1∶1.4、1∶1.5、1∶1.6)及 SS 与 BFS质量比(8∶2、6∶4)等因素对浆料的密度、流动度、析水率、结石率以及结石体单轴抗压强度(UCS)的影响,并结合XRD、TG、SEM等微观试验,分析了水化作用机理.研究结果表明:水固比相同时,随CFBFA掺量的增加,浆料流动度、结石率增大,而密度、析水率和UCS减小;原材料配比相同时,随水固比增大,浆料析水率增加,流动度、密度、结石率及UCS减小;水固比与CFBFA掺量相同时,随SS与BFS比值增大,浆料密度与析水率增大,流动度、结石率与UCS减小;CFBFA掺量、水固比对浆料工作性能的影响均显著,且CFBFA、BFS掺量对UCS影响大;结石体28 d UCS试件中仅有A1组的小于0.6 MPa,且最大值达16.71 MPa.综合考虑浆料工作、力学性能,同时结合经济性,提出了公路路基、桥隧下伏采空区注浆材料的施工建议配合比.浆料水化产物主要为C—S—(A)—H、AFt及Ca(OH)2,减小水固比、增加SS与BFS掺量、提高试件养护龄期均可使水化产物(C—S—(A)—H、AFt)数量增多,试件更密实,UCS更高,且BFS掺量增加有助于Ca(OH)2二次水化和AFt等水化产物的生成.实际应用中,通过调整CFBFA、SS、BFS与FGD全固废注浆材料配合比,其工作性能及UCS均能满足相关规范的要求,用于采空区注浆是切实可行的.
Research on Characteristics of Solid Waste Grouting Material of CFB Ash-steel Slag Powder-blast Furnace Slag for Goaf Underlying Highway
To solve the problems of high cost,energy consumption,and pollution associated with traditional cement-based grouting materials,a new type of green and environmentally friendly solid-waste grouting material for highways and underground goafs under bridges and tunnels was prepared using CFB fly ash(CFBFA),steel slag micropowder(SS),blast furnace slag(BFS),and desulfurization gypsum(FGD)as raw materials.Through a series of tests,the effects of different CFBFA dosages(80％,60％,50％,40％,and 20％),water-solid ratios(1∶1.3,1∶1.4,1∶1.5,and 1∶1.6),and SS-to-BFS mass ratios(8∶2 or 6∶4)on the density,fluidity,water evolution rate,stone formation rate,and uniaxial compressive strength(UCS)of the slurry were studied.The hydration mechanism was analyzed through microscopic experiments such as XRD,TG,and SEM.The research results show that for a constant water-solid ratio,but with an increase in the CFBFA content,the fluidity and stone content of the slurry increase,while the density,water precipitation rate,and UCS decrease.For a constant raw material ratio with an increasing water-solid ratio,the water precipitation rate of the slurry increases,while the fluidity,density,stone content,and UCS decrease.When the water-solid ratio and the CFBFA dosage remain constant while the SS to BFS ratio increases,the slurry density and water release rate increase,while the fluidity,stone content,and UCS decrease.The workability of the slurry is significantly affected by the content of CFBFA and the water-solid ratio,while the influence of the SS:BFS ratio is relatively small.For 28 d UCS,only that of group A1 is less than 0.6 MPa,of which the maximum value is 16.71 MPa.Considering the workability and mechanical properties of the slurry,as well considering the economic perspective,a recommended mix ratio for the construction of highway embankments,bridges,and tunnels in the goaf was proposed.The main hydration products of the slurry are C—S—(A)—H,AFt,and the intermediate hydration product is Ca(OH)2.Reducing the water-solid ratio,increasing the contents of SS and BFS,and increasing the curing age of the specimens can increase the number of hydration products(C—S—(A)—H,AFt),density of the specimens,and UCS.Moreover,increasing the BFS content generated secondary hydration products such as Ca(OH)2 and AFt.In practical applications,the workability and UCS of a slurry can meet the requirements of relevant specifications by adjustments to the mix ratio of the CFBFA,SS,BFS,and FGD solid waste grouting materials.Therefore,it is feasible to use these materials for goaf grouting.
subgrade engineeringCFB ash-steel slag powder-blast furnace slaghydration reac-tion mechanismgrouting material
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