预处理改善钢渣体积安定性的研究现状

 钢渣的体积不安定性不良是约束其用于道路材料的的主要因素之一。钢渣的体积安定性预处理是钢渣有效资源化利用的关键,也是提高钢渣在道路材料方向利用率的必备条件。针对钢渣的体积不安定性问题,分别从钢渣集料的特性、引起钢渣体积不安定性的因素、引起钢渣体积不安定性因素的测定方法和改善钢渣体积安定性的预处理措施4个方面综述了国内外对钢渣体积安定性的研究进展和现状。结果表明,钢渣集料的性能较好,但矿物成分复杂,其中引起钢渣体积不安定性的主要因素是游离氧化钙和游离氧化镁,其在一定条件下能使钢渣膨胀开裂,约束了钢渣的应用;乙二醇-EDTA-TG差热分析法和EDTA滴定法是测定钢渣中游离氧化钙和游离氧化镁含量较准确、较普遍的测定方法;国内大部分的预处理改善措施是针对钢渣中的游离氧化钙,包括自然陈化、蒸汽养护、表面改性处理、化学处理和碳化处理等,表面改性和化学处理为近几年钢渣的预处理措施热点,碳化处理能将钢渣膨胀率降低70%～90%,与其他处理措施相比效果较好,但对设备要求较高,成本较高;而国外主要是采取自然陈化的方式改善钢渣的体积安定性。因此,钢渣的预处理需要具有社会、经济、环境等效益的同时才能大规模应用,这需要科研人员更加深入地研究和探讨,最后结合前人的研究对未来钢渣资源化利用于道路材料的发展提出建议和展望。

Research status of improving volume stability of steel slag by pretreatment

The volume restlessness of steel slag is one of the main factors restricted its application in road materials. The volume stability pretreatment of steel slag is the key to effective utilization of steel slag, and also is the necessary condition to improve the utilization rate of steel slag in the direction of road materials. In view of volume restfulness for steel slag, the research progress and present situation of volume restfulness of steel slag at home and abroad are summarized from four aspects, that are, physical property of steel slag, factors causing volume restfulness of steel slag, determination methods of volume restfulness for steel slag and pretreatment measures for improving volume restfulness of steel slag. The results show that performance of steel slag is good, but the mineral composition is complex. The main factors causing the volume restlessness of steel slag are free calcium oxide and free magnesium oxide, which can make steel slag expand and crack under certain conditions and restrict the application of steel slag. Ethylene glycol-EDTA-TG differential thermal analysis and EDTA titration are more accurate and common methods for the determination of free calcium oxide and free magnesium oxide in steel slag. Most of domestic pretreatment improvement measures are aimed at the free calcium oxide in steel slag, including natural aging, steam curing, the surface modification treatment, chemical treatment and carbonization processing. Among them, surface modification and chemical treatment for pretreatment of steel slag measures are hot spots in recent years, while carbonization can cut steel slag expansive rate around 70% to 90%, which has better effect compared with other pretreatment measures, but its equipment requirements and costs are higher. Foreign countries mainly adopt natural aging method to improve the volume stability of steel slag. Therefore, the application on a large scale for pretreatment of steel slag needs to have social, economic, environmental and other benefits at the same time, which requires researchers to carry more in-depth research and discussion. Finally, suggestions and prospects for the future development of steel slag resource utilization in road materials are put forward based on previous studies.