植物纤维在水泥石孔溶液碱性环境下的劣化机理研究

For the sustainable development of construction industry, it is of great importance to explore a kind of environmentally friendly, new fiber reinforced cement based materials. Here, we propose a new method, simplified modeling research combined with actual cement hydration environment, for systematically investigating the degradation mechanism and regulating technology of plant fibers in cement based materials. As research object of the project, the main component of the plant fibers is cellulose. Firstly, the effects Ca2+ ion, OH- ion and Ca(OH)2 crystal on the degradation of plant fibers will be investigated by using a lime solution as a simplied cement solution. And then, introducing the different metal cation to the same alkaline environment will be attempted to demonstrate the degradation mechanism of plant fibers in the alkaline environment, solution with the same pH value. Furthermore, the degradation mechanism and the regulating measure of plant fibers in cement based materials will be explored on the basis of the physical, chemical and mechanical properties of plant fibers in different curing ages. The research results are expected to provide valuable theory support for design, preparation, and improvement of properties and engineering application of plant fibers reinforced cement based composites.

发展环境友好、新型纤维增强水泥基材料对建筑工业的可持续性具有重大意义。本项目以纤维素为主要组分的植物纤维增强水泥基材料为研究对象，系统研究植物纤维在模拟水泥石孔溶液、硬化水泥浆碱性环境下的性能劣化机理。首先以Ca(OH)2溶液作为碱性环境，研究Ca2+、OH-及Ca(OH)2结晶体对植物纤维性能的影响；其次，探究相同pH值碱性溶液、不同碱（碱土）金属离子对植物纤维性能的影响规律；最后，制备植物纤维-水泥基复合材料，连续监测不同龄期下其力学性能变化，并对植物纤维的成分、结构、微观形貌进行全面表征，探究植物纤维在硬化水泥浆碱性环境下的劣化机理，在此基础上提出植物纤维-水泥基复合材料性能提升调控技术。本项目以期为植物纤维-水泥基复合材料的设计、制备、性能提升及工程应用奠定理论基础。

本项目采用简化水泥石孔溶液的模型化研究与实际硬化水泥浆碱性环境研究相结合的方式，研究了水泥水化产物 Ca(OH)2、硬化水泥孔隙溶液碱度以及碱性环境条件下Ca2+、K+、Na+离子三种金属阳离子对植物纤维的影响规律。在明确植物纤维劣化机理的基础上，有针对性地提出改善植物纤维在硬化水泥浆体中劣化的调控手段。该项目的研究将Ca(OH)2对植物纤维的物理、化学作用进行了区分，明确了导致植物纤维在水泥基体中劣化因素的主次关系，进一步揭示了导致植物纤维在硬化水泥基体中劣化的主要原因为Ca(OH)2对植物纤维的物理作用。此外，项目有针对性地提出了植物纤维在硬化水泥浆体中劣化的调控技术，为植物纤维/水泥基复合材料的制备和工程应用提供理论基础。