Concrete bonding interface, which is easy to crack, has always been a weak part and become a worldwide technical problem. Through further study of the interface bonding mechanism, the "dual interface- multilayer zone" interface structural model and the "two- factor stress balance" interface close-fit mechanics model are innovatively introduced. And by combination of "stress- enhancement" and "stress-elimination", a new environmental friendly interface bonding material——new and old concrete interface bonding adhesive is developed. The cement-based cementitious material is used as the matrix. Various active powder materials are introduced to optimize the hydration reaction process, to improve the crystal structure and size of interfacial stone body, and to generate a denser and stronger mineral. And volume-swelling component and water-retaining component are added to reduce the volume shrinkage and dehydration shrinkage during the hardening process of adhesive, which ensures the volume stability during the hardening process. An appropriate amount of super retarding component is introduced to extend the setting time, which can use its plasticity to absorb most of the autogenous volume deformation and shrinkage deformation of the new concrete. Water-retaining materials and surfactants are added to improve the workability of bonding layer and the construction performance. These measures make the interface bonding layer have similar physical and mechanical properties with the old and new concrete, which not only improves the bonding strength of interface, but also effectively reduces the harmful interface constrainting stress, thereby making this combination stronger and more durable. The practical application to Danjiangkou dam heightening and other projects has proved that the concrete interface treated with the new and old concrete interface bonding adhesives has excellent bonding performance and significant adhesion effect.

concrete bonding interface, bonding strength, bonding adhesive, stone body, super retarding

混凝土结合界面一直以来都是易开裂的薄弱环节，界面黏结成为世界性技术难题。通过对界面黏结机理的深入研究，创新提出“双界面-多层区”界面结构模型与“双因素应力平衡”界面密合力学模型，采取“增强”与“消应”双管齐下的思路研制了一种新型的环保型界面黏结材料——新老混凝土结合界面密合剂。采用水泥基胶凝材料为基体，掺入多种活性粉体材料，优化了水化反应的进程，改善了界面结石体的晶体结构与尺寸，生成更致密、强度更高的矿物；掺加体积膨胀组分和保水组分，减小密合剂硬化过程中的体积收缩和失水干缩，保证了体积稳定性；加入适量的超缓凝组分延长密合剂凝结时间，利用其塑性吸收新混凝土的大部分自生体积变形和干缩变形；添加保水材料与表面活性剂，改善了黏结层的工作性，提高了施工性能。这些措施使界面黏结层与新老混凝土具有相似的物理力学性质，既提高了界面的黏结强度，又有效地削减了界面有害的约束应力，从而使这种结合更加牢固持久。经丹江口大坝加高等多个工程的实践应用证明，采用新老混凝土结合界面密合剂进行界面处理，黏结性能优异，密合效果显著。

混凝土结合界面, 黏结力, 密合剂, 结石体, 超缓凝