Preparation Of High - Strength Concrete With Micro - Silica Powder And Fly Ash And Its Acid Erosion Performance

With the growth of awareness of environmental protection, people have paid more and more attention to the utlization of industrial waste. Silica fume and fly ash are rich in resources, not only it is good for protecting environmental, but also it can produce good economic benefit. Mechanical properties of concrete dopped with fly ash and silica fume has been widely researched. However, the research of silica fume and fly ash used in concrete after acid leaching is limited. Based on silica fume and fly ash as the research object, the hydration and mechanical properties of cement paste was studied, at the same time, the acid resistance and mechanical properties of concrete with incorpation silica fume and fly ash is discussed. In test, dosage of silica fume is5%,10%,15%by weight of cementitious materials, dosage of fly ash is4%,12%,20%by weight of cementitious materials. In this paper, the main work and achievements are as follows:1. After adding silica fume and fly ash into cement paste, it has an effect on hydration performance. Silica fume can decrease the fluidity of cement paste; Fly ash can increase the fluidity of cement paste. In this paper, by analyzing slurry fluidity, combined with water, internal porosity, XRD spectrum, we find that silica fume and fly ash can improve secondary hydration and reduces the CH content and blocked pore formed CSH gel in the process of hydration, make the density of slurry, the strength is also improved.2. Using a42.5magnitude of cement and the right amount of water reducing agent under0.4water-binder ratio, single or double mixed with silica fume and fly ash can be prepared for high strength concrete. Only mixed micro silicon powder, the highest compressive strength of concrete is dosage of10%. Only mixing fly ash, it is not conducive to the early compressive strength increase, but will increase the later strength. Double mixing, the highest compressive strength of concrete is mixed with the amount of10%of silica fume and12%fly ash.3. Through analyzing quality loss and strength loss of concrete mixed with silica fume and fly ash immersing in5%H2SO4and5%CH3COOH solution for28d, we find that the calcium hydroxide amount of high strength concrete decreased because of adding the right amount of silica fume and fly ash, it can form CSH gel blocked pore and has good permeability resistance, leading to improve the resistance of concrete to5%H2SO4and5%CH3COOH erosion. Acetic acid resistance of concrete is worse than sulfuric acid resistance. Acetic acid and sulfuric acid resistance of concreteafter double mixing with10%silica fume and12%fly ash is better than single mixing10%silica fume or12%fly ash.