Self-sensing cement-based sensor with carbon nanotube: Fabrication and properties – A review

Abstract

Structural health monitoring is currently becoming more and more vital as it detects damage and warns users early. Since metallic sensors are less reliable and incompatible with concrete, their use in structural health monitoring is limited. This leads to the development of a nanomaterial embedded cement-based sensor. Cement composite is converted to a cement-based sensor due to its piezoresistive property. Thus, the paper examines the use of carbon nanotubes (CNT) in the development of cement-based sensors. The properties and optimum dosage of the CNT are also investigated to prepare the cement-based sensor. The manufacturing process determines the cement-based sensor properties, which is carefully examined and a manufacturing process is also proposed. The review explored that the sensor shows greater elongation capacity, compressive and flexural strength due to the CNT reinforcing capability, CNT properties, and stable interface connection with O–H bond formation. The cement-based conductive properties increase with an increase in CNT content due to contact conduction and tunnelling conduction. The analysis shows that the CNT disperses and distributes favourably in the composite through the acid treatment and sonication process, resulting in improved mechanical, conductive and piezoresistive properties. The cement composite exhibits stable piezoresistive properties with hybrid embedment due to pore filling capability, contact point increase, fiber spacing shortening and tunnelling effect. The reason for property enhancement was validated with the help of SEM investigations. This review gives a detailed insight into the material properties, sensor fabrication, mechanical, conductive and piezoresistive properties of the developed cement-based sensor.