Research On Application Technology Of Pre-treatment Jiugang Steel Slag In Road Base

Steel slag is one of the largest solid wastes.A large amount of waste steel slag piles up like mountains,which not only takes up the land resources,but also pollutes the environment.Therefore,the recycling of steel slag is one of the research hot spots in today's society.In the context of the vigorous development of highway engineering in China,the demand for natural stone materials continues to grow,and the acquisition of these materials will cause great damage to the environment.In order to achieve the dual benefits of economy and environmental protection,steel slag can be fully used to replace crushed stone for road base,which is expected to make steel slag be applied in a large number of reasonable ways.In order to promote the reuse of steel slag resources,this paper studies the properties of steel slag raw materials,the stability of steel slag volume and the properties of steel slag mixture.XRD,Scanning Electron Microscope,Electron Probe Microscope,Atomic Absorption Spectrometer and other precision instruments were used to explore the physical and chemical characteristics of the steel slag,and to verify the non-toxicity of the steel slag to the environment.Analysis of the feasibility of replacing steel slag with crushed stone,which shows that the performance of steel slag is better than that of stone,and the steel slag is an excellent substitute for natural stone.The biggest flaw in the promotion and application of steel slag is its potential volume expansion.When applied to road bases,local expansion hazards will occur.Therefore,in this paper,the index of water swell rate is used to characterize the potential expansion of this batch of steel slag,and the statistical theory is used for heterogeneous evaluation.The estimated range of volume expansion of this batch of steel slag is obtained under the 95%guarantee rate.The results show that the volume expansion of most steel slag meets the requirements,and only a small part cannot meet the requirements.Therefore,it is recommended that the steel slag can be used after pretreatment.In this study,pretreatment techniques such as water pretreatment at different temperatures,fly ash modification pretreatment,water and fly ash coupling pretreatment,and surface modification pretreatment were used.The results show that the rate of digestion of swelling components by water immersion pretreatment is proportional to the temperature,and the age required for the complete digestion of water immersion pretreatment at normal temperature is longer.The digestion efficiency at 60 ? water bath temperature is about twice that of normal temperature.90? water bath temperature digestion rate is the fastest rate;when mixed with fly ash,the expansion of steel slag gradually decreases with the increase of the amount of fly ash.When the dosage of fly ash is 12%,the purpose of reducing the potential expansion hazard can be achieved;the steel slag passes through water and fly ashcoupling pretreatment,the effect of reducing the swelling is more significant than when it is acting alone;the surface modification pretreatment can not only ensure the volume stability,but also improve its mechanical properties.By comparing the advantages and disadvantages of the four pretreatment techniques,the final selection of 12% fly ash dosage pretreatment steel slag.Different amounts of steel slag instead of crushed stone were used in cement stabilized steel slag crushed stone and cement fly ash stabilized steel slag crushed stone system,in order to study the influence of steel slag on the mechanical properties and durability of inorganic binder stabilized steel slag crushed stone aggregate.The results show that the performance change rules of the two binder systems are consistent,as the amount of steel slag increases,the unconfined compressive strength shows increases first and then decreases.The indirect tensile strength and compressive rebound mode is gradually increased,the ability to resist freezing damage is increased,the drying shrinkage performance is weakened,and the temperature shrinkage performance is showing an increasing trend.Considering all performance indexes comprehensively,the optimal content of steel slag should be 50%.Through paving test road,study construction process and quality control of cement fly ash stabilized steel slag crushed stone,through performance testing,during and after actual paving at various stages,verify the actual application effect of steel slag,and finally,The economic and social benefits of steel slag applied to road base are analyzed.