Fundamental Research On The High Performance Concrete Made By Iron Tailings And Iron Barren Rocks

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.