石墨尾矿混凝土受力和导电性能研究

Tailings that are abandoned in the process of graphite mining are rarely used and occupy land which cause serious environment problem in these years. In order to alleviate the environment problem and utilize tailings the following research should be performed. Experiment methods including liquid limit plastic limit, maximum dry density, the optimum moisture and solidification are adopted to study the feasibility of applying graphite tailings as road base material. Graphite tailings can be used as concrete aggregate for construction, road and bridge engineering, in which cement water ratio, sand coarse aggregate ratio, active mineral material content and grain content in the tailings are the focus issues because they affect the characteristics of the concrete including pressive strength, tensile strength, workability and frost resistance. Graphite tailing can improve the electric conductivity and varistor characteristics of the asphalt concrete and it can be used as electrically conductive concrete or intellectual material for structure detection and control. The static and dynamic stability of the asphalt concrete is studied when the graphite tailings are used as aggregate, so the mixing proportion of the asphalt concrete can be determined. Mechanical and electrical properties of the graphite tailing are the important influence factors that it can be used in the construction, water conservancy, bridge and road engineering, so the mechanical and electrical properties of the graphite tailing should be studied. These studies will not only solve the land and environment problem but also bring remarkable social and economic benefits.

我国多年的石墨开采遗留大量的尾矿，这些尾矿侵占土地，污染环境，至今未得到有效地开发利用。本项目将石墨尾矿杂质去除方法与五氧化二钒和云母的提炼相结合，采用石墨尾矿部分替代细骨料，研究水灰比、石墨尾矿掺量、砂率对混凝土抗压强度、抗拉强度、和易性以及抗冻性的影响。研究石墨尾矿混凝土的破坏机理。将石墨尾矿加入到沥青混凝土中，研究其对沥青混凝土稳定度和动稳定度等指标的影响，确定合理配合比。研究石墨尾矿掺量对混凝土和沥青混凝土导电性能的影响，研究石墨尾矿混凝土的压敏特性，进行配合比的优化研究。研究通过在石墨尾矿混凝土中加入碳纤维和钢纤维来进一步提高导电性能。研究将石墨尾矿应用到导电混凝土，工程检测、控制等领域。对石墨尾矿混凝土的力学、电学特性进行系统研究对节约土地资源，保护生态环境具有十分重要的意义，石墨尾矿广泛应用于建筑、水利、桥梁和道路工程中还会创造巨大的经济效益和社会效益。

我国多年的石墨开采遗留大量的尾矿，这些尾矿侵占土地，污染环境，至今未得到有效地开发利用。本项目在对石墨尾矿理化性能进行充分分析的基础上，采用石墨尾矿部分替代细骨料，研究石墨尾矿混凝土的受力性能、抗渗性能、抗冻性能和导电性能。采用石墨尾矿替代沥青混凝土中细集料，研究沥青混凝土的最大承载力、水稳定性能及高温稳定性能。采用宏观试验与微观试验方法相结合，研究石墨尾矿混凝土内部成分的作用机理，进行配合比的优化研究确定最大容许掺量和最优掺量。研究结果表明石墨尾矿混凝土抗压强度先随着石墨尾矿掺量的提高而提高，然后随着石墨尾矿掺量的提高而下降。水灰比越大，石墨尾矿对混凝土力学性能和耐久性能提高的效果越好，石墨尾矿的最大容许掺量越高。适量石墨尾矿掺入到混凝土中，一方面改善了混凝土的级配，密实度提高，另一方面也影响矿物和复合晶体形态和组成。当石墨尾矿掺量过多时，由于石墨尾矿的高吸水性，造成内部水化不完全，降低混凝土力学性能和耐久性能。石墨尾矿的掺入能够降低混凝土的电阻率，且随着石墨尾矿掺量的提高，电阻率呈先下降后趋于平缓的趋势。在不同的测量电压下，混凝土的电阻率和养护龄期都呈现线性相关，采用12V电压和四极法测量电阻率的结果最为准确。对于基质沥青混合料，石墨尾矿可以实现对混合料中0.075mm-0.6mm粒径范围的细集料的100%替换，最大承载能力、水稳定性能及高温稳定性能等方面均有显著提升。对于SBS改性沥青混合料，当石墨尾矿对0.075mm-0.6mm粒径范围的细集料替代量为50%时，其路用性能效果较好。本项目研究为石墨尾矿广泛应用于建筑、水利、桥梁和道路工程创造了条件，可以变废为宝，有助于降低混凝土成本，对节约土地资源，保护生态环境也具有十分重要的意义。