Self-sensing ultra-high performance concrete for in-situ monitoring

Abstract Owing to the excellent mechanical strength and durability, ultra-high performance concrete (UHPC) has been used for ultra-high, large-scale and military infrastructures. Endowing self-sensing properties to UHPC is conducive to realize in-situ monitoring and improve the safety of infrastructures. Therefore, the mechanical, electrical and self-sensing properties of UHPC with stainless steel fibers (SFs) and copper coated steel fibers (CCSFs) were studied in this paper. The results show that the addition of 1.2 vol% CCSFs can effectively improve the deformability of UHPC, as reflected by the improvement in peak compressive strain of 33.7%. UHPC with stainless SFs and CCSFs exhibits good synchronization and repeatability of self-sensing property under three different cyclic loading amplitudes within elastic regime. The highest strain sensitivity of UHPC with stainless SFs under 37.5 MPa of cyclic compressive loading is 26.6. Strain sensitivity of 28.2 is obtained for UHPC containing 1.2 vol% CCSFs under monotonic peak load, along with the monitoring compressive stress ranging from 0 to 125.7 MPa. The electrical resistivity of UHPC with stainless SFs and CCSFs can be used to in-situ monitor the stress, strain and damage development of structures.