Intelligent Design Of Ultra High Performance Cementitious Composites

With the high-speed social economic development, there is an urgent need to develop and use sustainable smart concretes which can alleviate and eliminate the serious obstacles and threats of ordinary concretes. Based on the preparation of ultra-high performance cementitious composites, the smart cementitious composites were prepared with the performance of self-healing and self-sensing by mixing with multi-scale fibers and changing material curing systems.Self-healing cementitious composites were prepared by mixing with different fibers. The influences of fiber types, repairing temperature, healing time, mineral admixture types and fine aggregates types were researched on the performance of self-healing. The damage of materials before and after self-healing was tested by the ultrasonic wave method. This nondestructive testing method can not only be used to measure materials self-healing performance, but also avoid introducing new materials damage and realize real-time detection.Carbon fibers were used to make cementitious composites have self-sensing performance. The effects of water binder ratio, carbon fiber content and alternating current frequency were researched on the self-sensing performance of cementitious composites.Based on the research of self-sensing and self-healing performance of the cementitious composites, electrochemical characteristics of the cementitious composites modified by carbon fibers and carbon nanotubes were also researched by AC impedance method. The AC impedance curves of the cementitious composites were tested and the material internal structures and performance were analyzed. The equivalent circuit model of electrochemical impedance spectrum was established to connect the materials performance with the component parameters in the model. The real-time nondestructive testing method of cementitious composites was realized by AC impedance.