铁尾矿基复合掺合料的制备及其混凝土性能研究

发布时间：2018-06-20 13:57

  本文选题：铁尾矿 + 复合掺合料　； 参考：《武汉理工大学》2015年硕士论文

【摘要】：将铁尾矿磨细作为混凝土掺合料已经成为铁尾矿利用的一种新途径。本文针对铁尾矿粉活性低、对混凝土力学性能及耐久性能影响不明确等问题,开展了以铁尾矿为基料,以磷渣、石灰石为辅料制备铁尾矿基复合掺合料(TPCA)的技术研究,并研究了掺TPCA复合掺合料混凝土的性能。运用数学最小二乘法研究分析了不同粉磨时间下铁尾矿粉及其28d抗压活性指数之间的关系;引入有效粉磨时间Q(min),从细度组合、原料配比、粉磨工艺及助磨剂四个方面对TPCA的活性提高技术及粉磨能耗降低技术进行了研究,并利用激光粒度分析、RRB方程拟合等手段研究了梯级粉磨顺序、梯级粉磨时间对采用梯级粉磨工艺制备的TPCA的粒度分布特征及胶砂活性指数的影响。研究结果表明:铁尾矿的活性随着粉磨时间的增加,具有增长不明显的特性。梯级粉磨制得的TPCA体系的工作性能及力学性能均优于单独粉磨和混合粉磨;将易磨性较差而活性较好的磷渣预先粉磨有利于TPCA粉料中磷渣细颗粒含量的增加,提高其整体活性;合理的粉磨时间有助于提高TPCA粉料颗粒分布的均匀性,提高胶砂流动度;适量的助磨剂三乙醇胺有助于提高TPCA粉料的细度,降低粉磨能耗。在Q=42.5min,原料配比铁尾矿:磷渣:石灰石=6:3:1,三乙醇胺掺量为0.04%时,利用梯级粉磨工艺制得的TPCA流动度比为100%,28d抗压活性指数为82%。采用TPCA配制了强度等级为C20~C55的预拌混凝土,并对比研究了掺TPCA与Ⅱ级粉煤灰、S95级矿渣粉复合掺合料混凝土的强度与耐久性。结果表明:掺入30%的TPCA可配制出C20~C55强度等级的混凝土,TPCA对混凝土强度的影响与与Ⅱ级粉煤灰相当,但低于S95级矿渣粉;掺入20~40%的铁尾矿基复合掺合料的混凝土的抗碳化、抗氯离子渗透和抗冻等耐久性能,略低于Ⅱ级粉煤灰与S95级矿渣粉复合掺合料的的混凝土,但影响并不明显。通过复合胶凝材料水化热、浆体强度、X射线衍射测试(XRD)和扫描电镜测试(SEM),对比研究了铁尾矿粉和TPCA在复合胶凝材料水化硬化过程中的水化机理。研究表明:铁尾矿粉自身具有微弱的水化活性,而TPCA的水化活性相比铁尾矿粉则显著提高,且其水化活性的发挥主要体现在水化后期。
[Abstract]:Grinding iron tailings as concrete admixture has become a new way of iron tailings utilization. Aiming at the problems of low activity of iron tailings powder and unclear influence on mechanical properties and durability of concrete, the technical research on the preparation of TPCA-based compound admixture of iron tailings with iron tailings as base material, phosphorus slag and limestone as auxiliary material is carried out in this paper. The properties of TPCA-doped concrete are also studied. The relationship between iron tailings powder and its 28d compressive activity index under different grinding time was studied by using mathematical least square method. The improvement of TPCA activity and the reduction of grinding energy consumption were studied in four aspects of grinding process and grinding aids. The step grinding sequence was studied by means of laser particle size analysis and RRB equation fitting. The effect of step grinding time on the particle size distribution and sand activity index of TPCA prepared by step grinding process. The results show that the activity of iron tailings does not increase obviously with the increase of grinding time. The working properties and mechanical properties of the TPCA system prepared by step grinding are better than those of single grinding and mixing grinding, and the pre-grinding of phosphorus slag with poor grindability and good activity is beneficial to increase the content of fine particles of phosphorus slag in TPCA powder and improve its overall activity. Reasonable grinding time can improve the uniformity of particle distribution and increase the flowability of cemented sand, and the proper amount of triethanolamine can improve the fineness of TPCA powder and reduce the grinding energy consumption. When the ratio of iron tailings: phosphorus slag: limestone is 6: 3: 1 and triethanolamine is 0.04, the flowability ratio of TPCA prepared by step grinding process is 100 / 28d and the activity index of TPCA is 82 / 28d when the ratio of iron tailings to phosphorus slag: limestone is 6: 3: 1 and the amount of triethanolamine is 0.04. The premixed concrete with strength grade C20C55 was prepared by TPCA, and the strength and durability of the concrete mixed with TPCA and grade 鈪，

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