滨海混凝土渗透智能抑制方法与作用机理研究

Regarding to the durability problem of concrete structures caused by seawater exposure, the protective technology by mixing water repellent agents directly in concrete shows excellent permeation-resistance for uncracked concrete, however it hardly works for cracked ones. In this proposal, an intelligent strategy to endow concrete self-resistant ability toward water penetration will be developed based on designing of intelligent microcapsules constructed by supramolecular materials. By investigating on the behavior of water penetration in unsaturated concrete before/after cracking, critical parameters affecting water penetration will be acquired, which will be used to guide the designing of microcapsules and intelligent water-resistance concrete. By taken chloride ions, the most contained ions in seawater as the stimuli, the microcapsules sensitive to concentration of chloride ions will be developed to achieve the control release of water-repellent agent as the seawater transportation, thereby building up concrete capable of self-resistance to water penetration. Via analyzing the relationship between the critical parameters of water-penetration and the process of controlled releasing, together with the change of parameters of water-penetration in concrete before/after cracking, the self-resistance mechanism and impact factors will be established. Through comprehensive analysis on the relationship of structures and activities, an evaluation system on self-resistance ability against water penetration will be created. The ultimate goal is to build up a general scheme of water-penetration self-resistance of unsaturated concrete, thereby providing a novel solution for prolonging the durability and safety of concrete structures in the wetting-drying zone.

针对海水侵蚀造成混凝土耐久性下降的问题，内掺防水剂的方法对新建混凝土效果显著，但难以避免开裂引起的抗渗性下降。本课题基于超分子材料体系，从设计智能微胶囊出发，发展混凝土水分渗透智能抑制新方法。通过对非饱和混凝土开裂前后水分渗透行为的深入研究，获得水分渗透关键参数，用于指导微胶囊及智能防水混凝土的设计；采用海水中含量最多的氯离子为触发因子，设计和制备氯离子浓度敏感的微胶囊，实现海水渗透过程中微胶囊对防水芯材的可控释放，达到混凝土智能防水的目的；研究水分渗透关键参数与微胶囊触发释放行为的关系，开裂前后混凝土水分渗透行为的变化，阐述智能抑制水分渗透的作用机制和影响因素；综合分析智能混凝土的构效关系，建立对水分渗透智能抑制方法抑制效果的评价机制。最终目标是建立滨海非饱和混凝土水分渗透智能抑制的整体方案，为滨海干湿交替环境下混凝土耐久性问题提供新的解决思路。

针对海水侵蚀造成混凝土耐久性下降的问题，内掺防水剂的方法对新建混凝土效果显著，但难以避免开裂引起的抗渗性下降。本课题从设计智能响应材料出发，发展混凝土水分渗透智能抑制新方法；阐述智能抑制水分渗透的作用机制；综合分析智能抗渗混凝土的构效关系; 建立对水分渗透智能抑制方法抑制效果的评价。取得的研究成果主要体现在两个方面：首先，以海水中含量最多的氯离子为触发因子，分别基于电荷屏蔽效应和共沉淀原理设计了两种氯离子触发微胶囊，实现海水渗透过程中微胶囊对防水芯材的可控释放，不仅实现了混凝土裂缝造成的抗渗性下降的自修复，更通过自主识别混凝土自身的联通孔隙，实现混凝土抗渗性提升高达72%；并且克服微胶囊一次性释放的局限，实现多次干湿循环作用下混凝土抗渗性的持续修复和提升；进一步，在总结微胶囊负载量及释放周期有限等自修复经验的基础上，发展混凝土循环仿生自修复系统，实现抗渗剂的持续补充与大体积裂缝修复，实现裂缝体积修复率高达75%，该方案有利于提升混凝土在高水压作用下的抗渗性，但尚处于研究的初步阶段，将在其他项目的资助下继续深入研究。本项目发展的材料及智能抗渗方法为混凝土提供了渗透性自适应调节方法，对提升混凝土的耐久性具有重要意义。