Preparation, mechanics and self-sensing performance of sprayed reactive powder concrete

The emergence of shotcrete provides a new idea for construction methods, but with the development of society, the traditional shotcrete has been unable to meet the needs of structure. Therefore, concrete with better material properties is needed to replace traditional shotcrete. Reactive powder concrete (RPC) is a well-known ultrahigh strength concrete and widely used. Its material properties are better than shotcrete. However, the sprayable performance of RPC and the properties of this sprayed materials have not been reported. Therefore, to make up for the deficiency of ordinary shotcrete, the material properties of sprayed RPC were studied in depth. Response surface method was used to study the effects of different silica fume content, fly ash content and steel fiber volume content on workability, mechanical properties and crack sensitivity. The sprayed reactive powder concrete (sprayed RPC) was proposed for the first time. All models were reliable through variance analysis. The performance of sprayed RPC was better when the workability was between 140 and 160 mm. When the silica fume/binder ratio was 15%, the fly ash/binder ratio was 13.203%, and the volume content of steel fibers was 2%, the mechanical properties and crack sensitivity of sprayed RPC can reach a satisfactory degree. By studying the workability, mechanical properties and crack sensitivity of sprayed RPC, the optimum mix ratio of sprayed RPC was obtained. Steel fiber sprayed RPC can detect structural damage. Results lay the foundation for popularization and application to practical engineering.