Title: Toward Structural Health Monitoring of Civil Structures Based on Self‑Sensing Concrete Nanocomposites: A Validation in a Reinforced‑Concrete Beam
Author(s): Diego L. Castañeda-Saldarriaga, Joham Alvarez-Montoya, Vladimir Martínez-Tejada & Julián Sierra-Pérez
Appears on pages(s):
Keywords: smart materials, structural health monitoring, self‑sensing, carbon nanotubes, cementitious composites, nanocomposites, civil structures
Self‑sensing concrete materials, also known as smart concretes, are emerging as a promising technological develop‑ ment for the construction industry, where novel materials with the capability of providing information about the structural integrity while operating as a structural material are required. Despite progress in the field, there are issues related to the integration of these composites in full‑scale structural members that need to be addressed before broad practical implementations. This article reports the manufacturing and multipurpose experimental characteri‑ zation of a cement‑based matrix (CBM) composite with carbon nanotube (CNT) inclusions and its integration inside a representative structural member. Methodologies based on current–voltage (I–V) curves, direct current (DC), and biphasic direct current (BDC) were used to study and characterize the electric resistance of the CNT/CBM compos‑ ite. Their self‑sensing behavior was studied using a compression test, while electric resistance measures were taken. To evaluate the damage detection capability, a CNT/CBM parallelepiped was embedded into a reinforced‑concrete beam (RC beam) and tested under three‑point bending. Principal finding includes the validation of the material’s piezoresistivity behavior and its suitability to be used as strain sensor. Also, test results showed that manufactured composites exhibit an Ohmic response. The embedded CNT/CBM material exhibited a dominant linear proportional‑ ity between electrical resistance values, load magnitude, and strain changes into the RC beam. Finally, a change in the global stiffness (associated with a damage occurrence on the beam) was successfully self‑sensed using the manu‑ factured sensor by means of the variation in the electrical resistance. These results demonstrate the potential of CNT/CBM composites to be used in real‑world structural health monitoring (SHM) applications for damage detection by identifying changes in stiffness of the monitored structural member.