Question

Discuss the smart concrete materials by self-sensing materials as a breakthrough resulting form use of nanotechnology

Answer 1

Self-sensing composites are becoming highly attractive for civil engineering applications to improve the safety and performance of structures. These smart composites show a detectable change in their electrical resistivity with applied stress or strain and this unique characteristic make them useful for health monitoring of structures. Till date, different forms of carbon composites, i.e. short fibre, continuous fibre, particles, nano fibres, nanotubes, etc. have been utilized for this purpose.

Regardless of long service life of civil engineering infrastructures, they cannot be considered as

maintenance-free. These engineering structures are the most expensive investments and assets of any

nation. Worldwide incidents of tragic failures of civil infrastructures remind that suitable measures

are required to avoid sudden collapse of civil structures and associated loss of money and lives.

Concrete is the most extensively used material in civil engineering structures. Due to some inherent

drawbacks of concrete, these structures weaken with time. The weakening and failure of concrete

structures occur mainly due to ageing of materials, aggressive environmental conditions, prolonged

usage, overloading, difficulties involved in proper inspection methods, and lack of maintenance

Within the microstructure of concrete, it contains numerous cracks in nano-scale. These cracks are

formed during manufacturing or use. With time, nano-cracks join to form micro-cracks, which in

turn, leads to formation of macro-cracks and failure of structures Through early detection of

these inherent damages, sudden collapse and accidents can be avoided. Timely detection of damages

and proper maintenance can greatly enhance the service life of concrete structures.

The process of monitoring of deformation and damage that occur within civil engineering

structures is commonly known as Structural Health Monitoring (SHM) . SHM is highly

essential for important civil structures such as nuclear power plants, dams, bridges, high-rise

buildings, and power utilities. An active monitoring system can, in real time and online, recognize

different defects and monitor damage, strain, and temperatures so that the optimal maintenance of the

structures can be undertaken to provide enough safety and life span. In general, a typical SHM

system consists of three major components: a sensor system, a data processing system (containing

data procuring, storage and transmission systems), and an evaluation system (comprising information

management and diagnostic algorithms). The primary step to set-up an SHM system is to use stable

and reliable sensing tools or sensors). Different sensors such as fibre optic sensors,

piezoelectrics, magnetostrictive sensors, self-sensing composite materials, etc. possess capabilities of

sensing various physical and chemical parameters related to the health of civil structures.

SHM Systems for Civil Engineering Structures:

1.fibre optic sensors

2 piezoelectric sensors

3.self sensing sensors