Research On Methods To Suppress The Expansion Of Steel Slags And Road Performance Used As Roadbed Filling Material

As the pace of our Iron and Steel industry is speeding up, the emissions of the steel slagare increasing year by year.Study and application of steel slags as road materials shows thatexpansion of steel slags is the most important factor affecting steel slags to be used widely. Somaking a rearch on the method to suppress the expansion of steel slags meets the requirementsof the actual project and has significant meaning to the academia and project.The paper studys the effect of the three methods to suppress the expansion of steel slags,about immersin treattment of the steel slag at room temperature, single mixing with mineralmaterials and companding with mineral materials, besides the paper studys the mechanism ofsuppressing the expansion of the steel slags with mineral materials by X-ray diffraction andanalysying the content of free-CaO. Based on this we make a research on the basicroadperformance, such as CBR, modulus of resilience and the unconfined compressive strength.Conclusions based on this research can beshown as following:(1) The expansion of the steel slags can be suppressed when the steel slags can besubmerged at room temperature, which decreases the compression strength and integrity of thesteel-slag mixture specimens. However, we can suppress the expansion of the steel slags bymixing the steel-slag mixture with mineral materials that can increase the compression strengthand integrity of the steel-slag mixture specimens.(2) Immersion expansion ratios of the steel-slag mixture increase gradually when thedosage increases with mineral materials single-doped. As to the effect of suppressing theexpansion of the steel slags, Silica fume is better than GGBS(Ground Granulated Blast FurnaceSlag), and GGBS is better than the fly ash.The dosage of the mineral materials inflents thestability of steel slags more greatly with compound mineral materials than kinds and ratios.Ithas a better effect to suppress the expansion of the steel slags with compound admixtures whenthe dosage is10%,and the ratio is1:1:2,1:2:1and2:1:1.(3) The result of XRD and test to the content of free-CaO show that steel-slag mixturemixed with mineral materials not only can suppress the expansion of the steel slags but alsoproduce some silicates that can increase the compression strength of the steel-slag mixture.Peakof C3S, C2S become more and more, and peak of free-CaO become less and less until lostwhen the dosage increases,and at the same time some calcium magnesium spinel (such asC3MS2), calcium ferrite, calcium aluminum spinel(such as C2AS) appears.(4) CBR value, modulus of resilience and water stability of steel-slag mixture getincreased when steel-slag mixture mixed with mineral materials and degree of compaction getincreased, which enhance the resistance ability to deformation of steel-slag mixture. whencuring age is28days, all the modulus of resilience of the specimens are more than2000MPa，and increase greatly. (5) The unconfined compressive strength can be improved when steel-slag mixture mixedwith mineral materials. When the moisture content is the optimum water content and steel-slagmixture mixed with compound mineral materials(the ratio of GGBS, fly ash and silica fume is1:1:2,the dosage is10percentage), the unconfined compressive strength gets improved moregreatly.