矿物掺合料-超高韧性水泥基复合材料自愈合优化设计与行为及机制研究

Cracking of hardened cementitious materials is the main cause upon its mechanics and durability degradation, and it is very difficult for traditional concrete with above millimeter crack width to realize self-healing. It is the urgent requirement of social sustainability development to explore a new cementitious material with minimum crack width which is beneficial to self-healing. This research aims to determine the key technical parameters by scientific selection mineral admixture, and to study the healing behavior under cyclic tensile damage and water, gas permeability test, then mineral admixture-engineered cementitious composites capable of robust self-healing functionality will be optimally designed. Using its unique tighter microcrack property combined with low water-binder ratio and pozzolanic effect of mineral admixture to realize effective self-healing potential are put forward. Using advanced testing techniques, in-situ continuous imaging of self-healing processes, and evolvement law of healing products and internal structure in multi-scale, especially accurate quantitative the intrinsic mechanical properties for each phase in micro/nano scale will be investigated. The purpose of the research is to reveal the effect of unhydrated cement and mineral admixture on self-healing, then the self-healing mechanisms in microscopic and submicroscopic levels will be clarified. This study opens a new technological approach for crack control and durability of cementitious materials.

硬化体开裂是导致水泥基材料力学及耐久性能劣化的主要原因，传统混凝土毫米级以上宽度的裂缝难于实现自身愈合。研究既能最大程度地降低裂缝宽度，又有助于自身愈合的新型水泥基材料是社会可持续发展的迫切需求。本课题拟通过科学选择利用矿物掺合料，确定关键技术参数，深入研究往复拉伸荷载及水、气等介质渗透作用下的自愈合行为，优化设计具有自愈合特性的矿物掺合料-超高韧性水泥基复合材料，提出利用矿物掺合料的二次水化效应及低水胶比和其所独具的更加紧密细小的多裂缝以实现水泥基材料良好自愈合特性的研究；联合采用现代先进测试技术，原位连续成像表征裂缝的自愈合过程，多尺度研究裂缝自愈合产物的演变规律及内部结构，尤其是从微纳米尺度上准确定量体系中各物相的本征力学性能，旨在阐明未水化水泥及矿物掺合料颗粒在自愈合过程中的影响作用，从微观、亚微观层次系统揭示自愈合行为及机制，为水泥基材料的裂缝控制和耐久性改善开辟新的技术途径。

水泥基材料的开裂一直是建筑工程界和学术界关注的焦点问题，传统混凝土毫米级以上宽度的裂缝难于实现自身愈合。矿物掺合料-ECC（MA-ECC）紧密细小的多裂缝特性不仅有助于裂缝自愈合的发生，有效地提高材料的使用性能和耐久性，而且为固体废弃物的资源化利用及水泥工业的可持续发展开辟了新的途径。本项目利用当地矿物掺合料原料，成功制备出了裂缝宽度更加微小、更有利于裂缝自身愈合的MA-ECC体系，完成了相关的设计理论，得到了关键技术参数。研究了国产PVA纤维对ECC性能的影响，进一步降低了成本及实现原材料的本土化，所制备的MA-ECC体系可实现裂缝宽度进一步降低、力学性能良好、结构更加致密。探究了粉煤灰细度及化学成分对ECC性能的影响，研究了带缝ECC在不同环境下的自愈合性能，为其耐久性提供理论依据。利用先进的测试技术，实现了对MA-ECC体系中裂缝自愈合过程的原位连续成像表征，阐明了自愈合产物的物相演变规律及体系的微纳结构，从微观、亚微观层次系统揭示了裂缝自愈合的行为及机制，对实现MA-ECC在实际工程中安全有效的应用目标具有重要的理论意义。