Application Of Steel Slag In Cement Stabilized Crushed Stone Base

Highway transportation has made great progress with the rapid development of our country’s economy.At present,China’s road development is facing some constraints: for instance,environmental protection prohibits mining of stone materials,leading to raw materials scarcity and rising prices,so that project costs increase;Common semi-rigid bases such as cement stabilized gravel used as the main bearing layer of the road surface,its crack resistance has been difficult to solve.Steel slag,as an industrial waste residue,has large emission,large accumulation,and causing serious environmental pollution in China.Some steel slags with good physical and mechanical properties,can be used as pavement materials,then its utilization rate will be greatly increased,reducing pollution to the environment.In this paper,steel slag produced by Rizhao Steel Plant is taken as the research object,and it is incorporated into cement stabilized crushed stone to replace some of the crushed stone,investigating the technical properties,raw materials,composition design of composite materials,road performance and construction technology to promote its application in the base.Initially,the feasibility analysis of using steel slag instead of crushed stone in the base layer was conducted by its physical and mechanical properties,chemical analysis,and water immersion rate tests.Afterwards,the mix proportion of cement stabilized crushed stone and steel slag base layer was designed.Three kinds of cement dosage and five types of steel slag were selected to form 15 mix proportions;the optimal cement dosage and steel slag content were selected based on the results of 7 d unconfined compressive strength test.Additionally,XRD and SEM microscopic tests were conducted to test the products produced by hydration reaction of steel slag and the microstructure changes after hydration of steel slag at different ages to analyze the formation mechanism of strength of cement stabilized macadam-steel slag.Secondly,unconfined compressive strength test,indirect tensile strength test,and compressive elastic modulus test were conducted on the optimal six types of cement stabilized crushed stone-steel slag mixtures,and the mechanical properties were studied with the steel slag addition and maintenance and the cement dose.In addition,dry shrinkage and temperature shrinkage tests were conducted on these six kinds of mixtures to study the effect of steel slag on the aging shrinkage of cement stabilized macadam and its effect on the temperature shrinkage.Finally,the construction process and quality control technology for the cement stabilized macadam-steel slag base layer were studied by paving the test road.The relevant tests were carried out during the paving process and after the completion of the paving to verify the steel slag in the actual project,and analyze economic and social benefits of its application in the base.