Development of cement-based strain sensor for health monitoring of ultra high strength concrete

In this research a cement-based strain sensor (CBSS) with high strength and self-sensing ability is developed, and the use of the high strength CBSS for structural health monitoring of ultra high strength concrete (UHSC) columns is evaluated. Results show that the CBSS with 0.5% brass-coated steel fibers has high compressive strength of >120 MPa. Its piezoresistivity shows little noise, indicating the resistance of the CBSS varies smoothly with the strain. After oven-drying, the repeatability and sensitivity of the piezoresistivity has greatly improved. When the CBSS is embedded in a UHSC column, damage monitoring of the UHSC column can be performed by means of increasing irreversible change in the resistance of the embedded CBSS. The embedded CBSS can sense strain as well as stress of the UHSC column up to a stress of 154 MPa. The piezoresistive behavior of the embedded CBSS undergoes three phases during the monotonic loading, and they are high sensitive, linear phase; medium sensitive, nonlinear phase; low sensitive, linear phase with the increase in load.