冻融-干湿循环下碳化多源固废流态固化土耐久性及劣化机理OA

[Purposes]To promote the use of industrial solid wastes such as red mud and carbide slag in engineering materials,a multi-source solid waste flowable solidified soil is prepared by using red mud,carbide slag,metakaolin,and magnesium slag as main constituents.[Methods]Carbonat-ed and non-carbonated specimens were produced and subjected to freeze-thaw cycles and wet-dry cy-cles,separtately.Changes in macroscopic appearance,mass loss rate,linear shrinkage,unconfined compressive strength,pH value,and electrical resistivity were examined,and the associated structur-al evolutions were analyzed with SEM and FTIR.[Results]The results indicate that both freeze-thaw cycling and wet-dry cycling lead to deterioration of the flowable solidified soil.During freeze-thaw cycles,the strength decreases continuously,whereas during wet-dry cycles it increases first and then declines.Carbonation improves the initial structure of the specimens.At the early stage of freeze-thaw cycling,mass loss and shrinkage reduce while early strength increases;however,this beneficial effect becomes less evident with increasing cycle number.During wet-dry cycles,the carbonated spec-imens show comparatively larger mass loss and shrinkage at later stages.Among different mixtures,the specimen containing 30%magnesium slag shows better stability with both environmental condi-tions.In both cases,the pH value decreases overall,and electrical resistivity shows a positive correla-tion with unconfined compressive strength.Microscopic observations further show that gel products gradually decrease during cyclic exposures,while pores and microcracks continue to develop,leading to progressive degradation of cementitious structure.