大混合材掺量超高强混凝土配制技术研究

发布时间：2018-06-05 15:26

本文选题：超高强混凝土 + 镍铁合金渣　；参考：《中国矿业大学》2014年硕士论文

【摘要】：超高强高性能混凝土自问世以来，凭借优异的力学性能、工作性能和耐久性能，在世界各地得到了广泛的重视和研究。但传统的超高强混凝土水泥用量较大，往往使用价格昂贵的原材料，且制备和施工工艺复杂，这都影响了其在工程上的推广应用。本文运用常规混凝土制备工艺，采用矿物掺合料（硅灰，矿粉，镍铁粉，粉煤灰等）复掺，配以形貌状态良好的粗细骨料，配制出了大混合材掺量（等量取代水泥50%以上）、高强度（120MPa以上）、高工作性（坍落度200mm以上）、低成本的超高强混凝土。通过复掺矿物掺合料的净浆和胶砂试验，研究了各因素下超高强胶凝材料的抗压强度和流动性能，并对相关机理进行了分析；在此基础上，研究了普通细集料混凝土和镍铁合金渣混凝土的抗压强度影响因素，对比了两者的工作性能，最后分析了超高强混凝土配制成功的原因。研究结果表明，大混合材复配的胶凝材料后期强度能超过纯水泥强度，可进行超高强混凝土的配制；镍铁合金渣混凝土比普通细集料混凝土具有流动性优势，在低水胶比下能密实成型，达到更高的强度。通过测定化学结合水量分析了超高强混凝土胶凝材料的水化程度，采用XRD衍射分析法和SEM扫描电镜法对超高强混凝土的微观性能进行了研究。研究结果表明，，在低水胶比下，大掺量矿物掺合料胶凝材料的水化程度不高。硅灰和矿粉早期活性较高，促进水化能力较强，粉煤灰后期有较大的促进水化作用，而镍铁粉活性则一直较弱，无明显的促进水化作用；镍铁合金渣主要矿物组成为辉石和铁镁橄榄石，不具备水化活性。镍铁合金渣超高强混凝土的骨料与浆体之间连接紧密，过渡区无明显的Ca(OH)2晶体，而是被C-S-H凝胶包裹，界面特性与普通混凝土相比有极大的改善。
[Abstract]:Ultra high strength and high performance concrete (UHHPC) has received extensive attention and research in the world because of its excellent mechanical properties, working properties and durability. However, the traditional ultra-high strength concrete cement often uses expensive raw materials, and the preparation and construction technology is complex, which affects its popularization and application in engineering. In this paper, using conventional concrete preparation technology, mineral admixtures (silica fume, ore powder, nickel iron powder, fly ash, etc.) are mixed with coarse aggregate with good morphology. The superhigh strength concrete with large mixing amount (equal amount replacing more than 50% cement), high strength (above 120MPa), high workability (slump above 200mm, low cost) was prepared. The compressive strength and fluidity of ultra-high strength cementitious materials under various factors were studied through the tests of cement paste and cement sand mixed with mineral admixtures, and the related mechanism was analyzed. The factors affecting the compressive strength of ordinary fine aggregate concrete and Ni-Fe alloy slag concrete are studied. The working performance of the two concrete is compared. Finally, the reasons for the success of superhigh strength concrete preparation are analyzed. The results show that the post-strength of the compound cementing material of large mixing material can exceed the strength of pure cement, and the superhigh strength concrete can be prepared, and the Ni-Fe alloy slag concrete has the advantage of fluidity over ordinary fine aggregate concrete. At low water binder ratio can be compacted to achieve higher strength. The hydration degree of super high strength concrete cementitious material was analyzed by measuring chemical binding water. The microcosmic properties of super high strength concrete were studied by XRD diffraction and SEM scanning electron microscopy. The results show that the hydration degree of the cementing material with large amount of mineral admixture is not high at low water / binder ratio. The activity of silica fume and mineral powder in the early stage is higher and the hydration ability is stronger than that in the later stage of fly ash, while the activity of Ni-Fe powder is always weak and has no obvious effect on hydration. The main mineral composition of Ni-Fe alloy slag is pyroxene and ferric forsterite, which have no hydration activity. The superhigh strength concrete of Ni-Fe alloy slag has a close connection between the aggregate and the paste, and there is no obvious Ca(OH)2 crystal in the transition zone. Instead, it is wrapped in C-S-H gel, and the interfacial characteristic is greatly improved compared with the ordinary concrete.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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