节点文献
利用密云尾矿废石制备高性能混凝土的基础研究
Fundamental Research on the High Performance Concrete Made by Iron Tailings and Iron Barren Rocks
【作者】 刘佳;
【导师】 倪文;
【作者基本信息】 北京科技大学 , 矿业工程, 2015, 博士
【摘要】 为了开发大宗工业固体废弃物资源化利用的新途径,满足社会对绿色、高性能、高耐久性建筑材料的需求以及推动混凝土行业的可持续发展,本文以精细化综合利用为目标,采用铁尾矿和废石为主要原料依次研发出三种新型绿色高性能混凝土:铁尾矿细骨料混凝土、全尾矿废石骨料高性能混凝土和极细铁尾矿粉混凝土。全部利用铁尾矿砂作为骨料制备出标准养护条件下28d抗压强度达到100MPa的铁尾矿细骨料混凝土,固废总利用率达到89.2%。铁尾矿细骨料混凝土最优配合比为:铁尾矿比例占60%,粉煤灰比例占12%,矿渣比例占14%,水泥熟料比例占10.8%,脱硫石膏比例占3.2%,PC高效减水剂用量为胶凝材料的0.23%,水胶比0.22。在铁尾矿细骨料混凝土基础上加入废石作为粗骨料,制备出塌落度为136mmm,标准养护条件下28d抗压强度达98.54MPa的全尾矿废石骨料混凝土,其尾矿废石掺量达到72%,水泥熟料掺量仅为7.56%,固废总利用率达到92.44%,并且其在抗冻融和抗硫酸盐侵蚀等耐久性方面具有优异的性能。通过XRD、XPS、IR、SEM, TG-DSC、水化放热规律和孔结构测试等分析手段可知,水化各龄期C-S-H凝胶和钙矾石是强度的主要来源。在全尾矿废石骨料混凝土的基础上,采用目前难以利用的极细铁尾矿粉作为矿物掺合料,制备出在标准养护条件下28d抗压强度为88.99MPa的极细铁尾矿粉混凝土,尾矿废石利用率达77.6%。并对极细铁尾矿中所含有的石英、钠长石、拉长石、绿泥石和黑云母五种主要矿物成分进行水化反应活性的研究,结果表明标准养护条件下石英、绿泥石和黑云母反应活性较低,而钠长石和拉长石反应活性较高,其水化产物主要为钙矾石类矿物,对水化硬化浆体的强度有所贡献。将铁尾矿和废石等工业固体废弃物应用于高性能混凝土的研发中,不仅可以降低尾矿废石等固废对环境造成的负面影响,还能减少高性能混凝土原材料的碳足迹,并且提高产品附加值,从而有利于整个行业的可持续发展。
【Abstract】 In order to develop the new way of recycling the huge amount of industrial solid wastes, meet the social requirements of green high performance and high durability concrete, and promote the sustainable development of the concrete industry, in this paper, taking the solid wastes comprehensive utilization as target, developed three following kinds of new type green high performance concrete with iron tailings and barren rocks as part of the raw materials:concrete with iron tailings as fine aggregates, high performance concrete with whole tailings and barren rocks as aggregates, concrete with ultra-fine iron tailings powder as admixture.Concrete with iron tailings as the whole fine aggregates were developed, and the compressive strength of this fine concrete at28curving days was100.1MPa under standard curing condition, meanwhile the ratio of solid wastes used as raw materials in this concrete came to89%.The proportioning of optimized concrete is consist of iron tailings60%, fly ash12%, ground blast furnace slag14%, cement10.8%, and the desulfurization gypsum3.2%by mass fraction, PC plasticizer0.23%of the gelled material by mass fraction, the water-binder ratio is0.22.Barren rocks were used as aggregates on the basis of fine concrete mentioned above to develop high-performance concrete which had the slump of136mm, compressive strength of98.54MPa under standard curing conditions at28days, the ratio of cement is7.56%in this concrete, meanwhile the ratio of iron tailings and barren rocks is72%, as result the ratio of total industrial solid wastes in this high performance concrete is up to92%by mass fraction of the raw materials. In addition this concrete also had excellent performance in the durability test such as frost resistance and sulfate corrosion resistance and so on. Hydration mechanism analysis by XRD, XPS, IR, SEM, TG-DSC, exothermic analysis of hydration shows that C-S-H and ettringite is the main source of the mechanical strength at various curing ages.On the basis of high-performance concrete mentioned above, using ultra fine iron tailings powder as mineral admixture, developed the ultra fine iron tailings concrete which had the compressive strength of88.99MPa under standard curing condition at28days, meanwhile the ratio of iron tailings and barren rocks is77.6%. In order to study the hydration activities of ultra fine iron tailings powder as admixture in standard curing condition, the hydration processes and strength properties of quartz, albite, labradorite, chlorite and biotite which were the five mainly components in the iron tailings were studied, the results showed that quartz, chlorite and biotite had very low hydration activities, while the albite and labradorite had high hydration activities relatively, the hydration products of albite and labradorite were mainly including ettringite which contribute to the increasing strength of the hydration cure paste.The utilization of industrial solid wastes such as iron tailings and barren rocks in the development of high performance concrete, can not only reduce the carbon footprint of the raw materials in concrete industry, but also reduce the negative effects on the environment, and even improve the additional value of the concrete, then is beneficial to sustainable development of the whole industry.
【Key words】 Iron tailings; Iron barren; High-performance concrete; Flyash; Monomineral;