反应烧结碳热还原含钛高炉渣及其在导电混凝土中的应用基础研究

As a solid waste, the Ti-bearing blast furnace slag is usually dumped in the slag yard, which puts pressure on society in terms of both environmental pollution and waste of titanium resources. Considering that there are a great deal of conductive TiC and residual carbon in the carbothermal reduction product of Ti-bearing blast furnace slag, the project provides an innovative idea of preparing conductive concrete using Ti-bearing blast furnace slag on the base of our previous researches on the conductive materials and concrete. The project will systemically investigate the evolution of phase composition and microstructure of the carbothermal reduction product of Ti-bearing blast furnace slag during the reactive pressure-less sintering. The mechanism on the formation, distribution and growth of TiC grains will be studied. The project will clarify the microscopic mechanism on the coupling of mechanical and conductive properties of the carbide slag. When the relationship between the properties of conductive aggregates and those of concrete is clear, and the formation mechanism on integrated structural and functional properties of conductive concrete is revealed, the project will improve both mechanical and conductive properties of the concrete with an effective balance by controlling the properties of aggregates and the microstructure of the concrete. The development of this project will comprehensively and systematically solve the basic scientific problems on the preparation of conductive concrete from Ti-bearing blast furnace slag. It provides scientific basis for the comprehensive mass utilization of Ti-bearing blast furnace slag with high additional values and the development of novel structure & function integrated conductive concrete.

含钛高炉渣作为固体废弃物，给社会带来了环境污染和钛资源浪费的双重压力。针对含钛高炉渣的碳热还原产物（碳化渣）中含有大量导电TiC和残留碳这一特性，结合申请者在导电材料和混凝土领域的研究基础，本项目提出以反应烧结所得含钛高炉渣的碳化渣为集料制备导电混凝土的创新思路。项目拟系统研究无压反应烧结过程中碳化渣的物相组成与显微结构的演变规律，探索其中TiC晶粒的形成、分布及生长机制，阐明碳化渣的力学性能和导电性能相互耦合的微观机理；在明确导电集料（破碎后的碳化渣）性能与混凝土性能间的关系，揭示导电混凝土的“结构-功能”一体化形成机制的基础上，通过调控集料的力-电综合性能和混凝土的显微结构，实现对混凝土力学和导电性能的有效兼顾。本项目的开展将全面系统解决以含钛高炉渣制备导电混凝土的相关基础科学问题，可为含钛高炉渣全组分、高附加值、大宗量资源化利用和开发新型“结构-功能”一体化导电混凝土奠定理论基础。

含钛高炉渣作为固体废弃物，堆弃于渣场，给社会带来环境污染和钛资源浪费的双重压力。含钛碳化渣是含钛高炉渣经过高温碳热还原后所得的产物，鉴于其中含有大量导电TiC和残留碳这一特性，项目以其为导电集料，探讨其对导电水泥砂浆力学和电学性能的影响。研究发现，当以含钛碳化渣取代标准砂为集料时，不仅可提高水泥砂浆的抗压强度，还能有效降低水泥砂浆的干燥电阻率，但电阻率仍然高达1.7×104 Ω.m。当添加石墨作为导电相时，用含钛碳化渣替代标准砂为集料可使导电石墨水泥砂浆的渗透阈值从15 wt%降低到10 wt%。当石墨含量为10 w%时，含钛碳化渣-石墨水泥砂浆具有优异的综合性能：28天抗压强度为34.0 MPa，电阻率在潮湿环境和干燥环境下分别为4.9 Ω m和 2.9 Ω m。当添加碳纤维作为导电相时，含钛碳化渣替代标准砂作为集料可将碳纤维水泥砂浆的渗流阈值由0.5 wt%降低至0.2 wt%。当碳纤维含量为2.0 wt%时，碳化渣作为集料制备的导电水泥砂浆表现出优异的性能，28 d抗压强度为39.9 MPa，电阻率在潮湿环境和干燥环境下分别为10.7 Ω m和10.9 Ω m。以上结果表明，含钛碳化渣适合作为石墨水泥砂浆或碳纤维水泥砂浆的导电集料。项目的开展为含钛高炉渣全组分、高附加值的大宗量综合利用和开发低成本 “结构-功能”一体化导电水泥基复合材料奠定了一定的理论基础。