High-volume Refined Steel Slag Water-stabilized Road Base Performance Study

Since 1996,China’s annual steel output has been occupying the leading position in the world.As a by-product of steel production,steel slag has become a problem of environment and resource reuse that can not be ignored.Therefore,in order to realize the harmless and resource utilization of steel slag,this paper takes the refining steel slag of Chengde stainless steel plant in Beihai of Guangxi as the research object,carries out experimental analysis on its chemical composition,moisture content,physical properties and heavy metal precipitation of harmful substances.Aiming at the characteristics of its particle size,non activity,existence of heavy metal components such as hexavalent chromium and its easy cracking in highway application,a special road is developed The low shrinkage and anti cracking steel slag mixture was prepared with activator,and its mechanical properties and safety were verified,which provided reference for the popularization and application of refined steel slag in road engineering construction.The main research contents and achievements are as follows.（1）The physical and chemical properties of different groups of steel slag were analyzed after drying,and the corresponding micro properties of refining steel slag were analyzed by SEM and X-ray diffraction.The conclusion is that the refining steel slag obtained in this paper has high initial moisture content,its main chemical components are Cao,Si O₂,Mg O,Al₂O₃,P₂O₅,and the particle size is mainly distributed in the range of 0.075-2.36mm A certain degree of activity and gelation.At the same time,the content of f-Ca O and f-mgo in the steel slag is far lower than the limit value of the specification,so it belongs to weak expansibility and has good stability.（2）Through 7d unconfined compressive strength test,the influence of two kinds of activators with different contents on the compressive strength of pure cement stabilized steel slag mixture and cement crushed stone stabilized steel slag mixture was determined.The results show that the addition of activator can significantly improve the compressive strength of steel slag mixture.The pure cement stabilized steel slag test block with 8%cement content and 4.75%activator content has 7d unconfined compression strength The strength can reach 8.13mpa.（3）By comparing the compaction test and 7d,28d unconfined compressive strength test and other experimental results,the best mix proportion of the mixture is selected.The experimental results show that the compressive strength of the pure cement stabilized steel slag mixture with the same activator and cement content is better than that of the cement stabilized steel slag mixture,and the cement content is directly proportional to the compressive strength of the steel slag mixture,but the amount of cement is too high It is easy to cause the strength to exceed the standard,and finally the cement hydration causes the drying shrinkage cracking.Finally,8%cement and 3.75%activator are selected as the optimal mixture ratio,and the 7d and 28d compressive strength reaches 7.22mpa and 7.962mpa respectively,and the 90d splitting strength is 1.634mpa,and the 90d bending tensile strength is 2.416mpa.（4）The dry shrinkage property,frost resistance and heavy metal content of the selected mixture were tested.The conclusion was drawn that the addition of activator can effectively inhibit the shrinkage of the water stable material of refining steel slag.At the same time,the freeze-thaw damage of the mixture containing activator is smaller than that of the sample without activator.It can be seen that the activator can also improve the frost resistance of the mixture.Finally,the content of heavy metals in cement stabilized steel slag mixture with activator is only one tenth of the standard requirements,and is far lower than that of steel slag solid raw materials without activator.The activator also has a favorable effect on the release of heavy metals in the mixture.（5）In Tieshangang solid waste industrial park of Beihai City,the mixture ratio of steel slag:88.25%,cement:8%,activator:3.75%and water 20.3%was laid in the plant area of Tieshangang solid waste industrial park in Beihai city.It was found that the mixture ratio of steel slag was better as pavement base material;however,due to the hot weather in Beihai City,the water content was affected,which led to its easy water loss and dry shrinkage cracking Therefore,the water content should be controlled in engineering practice to avoid the same problem.