Experimental Study And Microscopic Mechanism Analysis Of Steel Slag Mixed Soil

With the fast development of the national economy,the metallurgy industry is growing rapidly.According to the latest data,the China’s steel output has ranked first in the world,with the fast growing of steel production capacity,large amounts of metallurgy solid wastes-steel slags are also produced.In recent years,although the government has a great investment in the recycle of metallurgy wasted resources,the comprehensive utilization rate of the steel slags is only 29%,with the limitations of treatment techniques and costs,which has a large gap comparing with the developed countries.Large amounts of piled steel slags not only takes up land resources,but also seriously pollute the environment.The existing researches demonstrate that the steel slag has a potential gelling property with a high strength,but is water-swelling.Besides,the environmental protection policies are becoming much stricter,the exploit of sand and stone for road engineering is restricted,and price is rising sharply;during the process of road engineering,the earthwork becomes much more difficult and the cost is rising.Based on that,this article has relative trials on soil solidification,the decomposition and activation of steel slags,the mixture of steel slags and soils,study this new type of road base material,steel slag mixed soil,draws the conclusion of the following researching results:（1）Select three type of ionic soil stabilizers and the soils from Ma Anshan district,by changing the mixing volumes of stabilizers and cements,observe the 7 days’result of unconfined compression strength,after that the YFS type of ionic soil stabilizer is ascertained as the best stabilizer and the perfect mixing ratio was 0.02%of YFS type ionic soil stabilizer and 5%of water.Through the unconfined compression strength test of stabilized soils,it is found that the soils demonstrated a good water stability under different immerse time,the curve of stress-strain is adhered to the strain softening concepts of soil mechanics,the strength of stabilized soils:increase first and then decrease with the increasing amount of stabilizers,and reaches its climax in0.02%;increase with the adding of cement;increase with the growing age;increase first then decrease with the increasing of moisture content,and reaches its climax in optimum moisture content;increase with the growing of compactness;the the standard maintenance value is slightly larger than the indoor maintenance value.（2）Through the experimental analysis of soil micro structure,the ionic type stabilizer makes soil particles render hydrophobic,the contacts between particles are greatly improved,aggregate is the main form of the particles,with the growing volume of aggregates,porosity of particles is decreasing,the hydration materials of cements fills the gaps,making the overall structure more densely.（3）Through the deals of soil stabilization and steel slags’decomposition,experimental results of steel slag mixed soils show that the volume’s swelling rate increases with the amount of slag powders in the blast furnace,10 days’swelling rate gradually reduces and adheres to the national standards within 2%.Take the 7 days’unconfined compression strength as reference to have a slag and soil match experiment,it shows 50%of steel slags and 50%of soils is the optimum ratio.Though the experimental study on factors affecting unconfined compression strength of steel slag mixed soil with optimum mix ratio,it is found that the curve of stress-strain is a parabola,its strength:increase with the growing of compactness;The value of standard maintenance value is slightly larger than the indoor maintenance value.Under different immerse time,these samples demonstrate a good water stability.（4）Through the XRD,SEM tests of the steel slag mixed soils,the analysis on repression of swelling and strength mechanism demonstrated that:Si O₂of slag powders in blast furnace had digestion reaction with f-Ca O of the steel slags;meanwhile,the modified performance of soil particles promotes the enhancement of the steel slags and soils,the hydrophobic nature of soil particles blocks the sufficient contacts between outside free water and steel slags and represses the f-Ca O hydration reaction of the steel slags;Under alkaline conditions of the slag’s powders within a blast furnace,the potential gelling property is activated and generates the gelling material C-S-H,fills the gaps between soil particles,and has double-extrusion with each group’s mixtures,decreases the overall porosity of steel slag mixed soils,makes it more densely and increases its strength.（5）Use the steel slag mixed soils to build road base of a parking lot in BOC gases co,ltd in Ma Anshan,and put forward relative construction technologies and methods,have tests for the compaction,modulus of elasticity,swelling amount of the formed steel slag mixed soils,the results turn out to meet the national road base standards.