树脂调控自养护路面混凝土水化行为及细微观结构演化机制研究

Exposed to the external environment, the serious problems of pavement concrete,such as crack initiation and insufficient hydration, will occur after the concrete forming mainly attributed to the moisture evaporation and hydration consumption.When the internal humidity of cement concrete drops, concrete can be cured by continuous moisture release of superabsorbent polymer.Then its microstructure will be filled efficiently during the hydration process and the original damages can be reduced.This project intends to be performed following the technical research routine of ‘Analysis of competitive aspiration and water redistribution behavior-Characterization of hydration behavior-Evolution and regulation of microstructure’. Based on osmotic pressure theory and gelling materials science, the competitive aspiration behavior between SAPs and cement particles will be explored, and thermal neutron imaging technology will be used to analyze the intervention effect of SAP on water movement distribution. The water conversions in various forms will be dynamically studied, and a thermo-electric model of hydration kinetics will be established to reveal the mechanism of hydration enhancement. Based on modern image reconstruction and tracking technology, the trade-off relationship between SAP self-supporting residual pores and hydration filling effect will be explored, and the microstructure evolution mechanism of pore and cement-aggregate interface zone will be revealed. Finally, the microstructure control strategy will be built, which uses the hydration reaction characteristic parameters as the quantitative reference system. The results of this research will provide theoretical basis and technical support for the effective regulation and optimization of microstructure of pavement concrete.

路面混凝土裸露于大气中，成型后因水分频繁蒸发及自身水化耗水造成的微裂缝萌生、水化不足问题显著。高吸水性树脂(SAP)能够在水泥混凝土内部湿度下降时持续释水进行自养护，实现高效水化填充，降低原始损伤程度。本项目拟以“竞争吸液及水分重分布行为解析-水化行为表征-细微观结构演化与调控”为研究主线，基于渗透压理论及胶凝材料学，探索SAP-水泥颗粒竞争吸液行为，运用热中子成像技术解析其对水分迁移分布的干预效应；动态研究各形式水分转化规律，建立水化动力学热-电模型，深入揭示水化增强机理；基于现代图像重构及追踪技术，探索SAP自养护残留孔与水化填充效应之间的权衡关系，揭示孔隙及水泥石-骨料界面区细微观结构演化机制，最终构建以水化反应特征参数为量化参考体系的细微观结构调控策略。本研究成果将为路面混凝土细微观结构的有效调控及优化提供理论依据和技术支撑。

路面混凝土裸露于大气中，成型后因水分频繁蒸发及自身水化耗水造成的微裂缝萌生、水化不足问题显著，进而增大路面服役期耐久性劣化风险。常规洒水、覆盖薄膜保湿、喷洒化学养护剂等方式难以保证水分充分养护路面混凝土内部结构，无法解决早期微裂纹的产生及水化不足的问题。高吸水性树脂自养护剂能够在水泥混凝土内部湿度下降时及时释水进行养护，实现高效、全方位的水化填充，降低水泥混凝土原始损伤程度。但是，对于自养护路面混凝土水分迁移规律、水化行为及细微观结构演化调控机制的研究尚少涉及。因此，本项目以“高吸水性树脂吸-释水及水分迁移规律解析-水化行为表征-细微观结构演化与调控”为研究主线，主要研究内容及成果如下：（1）探索了高吸水性树脂自养护剂物理特征及溶液环境对其吸液响应性的影响规律，分析了高吸水性树脂溶胀过程中新拌路面混凝土流变性能的时变规律；（2）确了自养护路面混凝土自养护水、毛细水、凝胶水、化学结合水等各形式水分之间的转化规律，揭示了高吸水性树脂“储液-释液”功效对路面混凝土化学结合水含量的作用效应；（3）研究了高吸水性树脂自养护路面混凝土水化初期宏观热学效应，以化学反应动力学角度分析了高吸水性树脂对水泥水化反应速率和水化半衰期的影响规律；（4）全面开展了自养护路面混凝土各阶段的水化反应动力学研究，并定量表征了高吸水性树脂-水泥体系的后续水化反应程度，揭示了水化增强机理；（5）研究了自养护路面混凝土孔结构参数演化特征，分析了自养护水化促进作用对水泥石-界面过渡薄弱区的离子传输特性的改善效果，阐明了其细微观结构演化调控机制。以上研究成果为高吸水性树脂自养护剂在公路工程领域的科学使用提供了理论指导和依据。