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Non-destructive testing

Concrete is the most extensively used construction material in the world, twice as much concrete is used in construction around the world than the total of all other building materials, including wood, steel, plastic and aluminium. Concrete is used as building material for architectural structures, pavements, roads, bridges and more. About seven cubic kilometers of concrete is made each year, more than one cubic meter per every person on Earth. Currently the lifetime of much of the concrete structures such as bridges is expiring, but there are few non-destructive methods available for determining when the structures need to be renewed.


A bridge that has collapsed due to fatigue rather than an earthquake.

KimmoViikkipieni2.jpg Electrical imaging of concrete

We develop non-destructive methods for the assessment of the condition of concrete and other solid structures, using diffuse tomographic methods such as electrical impedance tomography and thermal diffusion tomography. The new imaging modalities are expected to provide information on the degree of cracking, moisture distribution, condition of the reinforcement bars and microproperties of concrete. In addition to concrete, we are also interested in the determination of the thermal properties of solids, such as manmade composites and rock.

All the developed methods yield estimation problems that are severely ill-posed inverse problems. Due to the practical measurement setting, there are several uncertainties, which implies the adoption of the Bayesian framework for inverse problems


Tomographic methods can reveal cracks that are not visible on the surface.


Past and present collaborators

  • Professor Paulo Monteiro, University of California Berkeley, Department of Civil and Environmental Engineering.

  • Professor Mohammad Pour-Ghaz, North Carolina State University, Department of Civil, Construction, and Environmental Engineering.

Recent publications

Sensing skins


A. Seppänen, M. Hallaji, M. Pour-Ghaz
A functionally layered sensing skin for the detection of corrosive elements and cracking
Structural Health Monitoring, 2017 (Published online)


M. Hallaji, A. Seppänen, M. Pour-Ghaz
Electrical impedance tomography-based sensing skin for quantitative imaging of damage in concrete
Smart Materials and Structures, 23: 085001, 2014.

Monitoring of moisture transport in concrete


D. Smyl, R. Rashetnia, A. Seppänen, M. Pour-Ghaz
Can electrical Impedance Tomography be used for imaging unsaturated moisture flow in cement-based materials with discrete cracks?
Cement and Concrete Research, 91: 61-72, 2017.


D. Smyl, M. Hallaji, A. Seppänen and M. Pour-Ghaz
Three-dimensional electrical impedance tomography to monitor unsaturated moisture ingress in cement-based materials
Transport in Porous Media, 115: 101–124, 2016.


D. Smyl, M. Hallaji, A. Seppänen and M. Pour-Ghaz
Quantitative electrical imaging of three-dimensional moisture flow in cement-based materials
International Journal of Heat and Mass Transfer, 103: 1348–1358, 2016.


M. Hallaji, A. Seppänen and M. Pour-Ghaz
Electrical Resistance Tomography to Monitor Unsaturated Moisture Flow in Cementitious Materials
Cement and Concrete Research, 69: 10-18, 2015.



K. Karhunen, A. Seppänen, J.P. Kaipio
Adaptive meshing approach to localization of cracks with Electrical impedance tomography
Inverse Problems and Imaging, 8: 127 – 148, 2014.


K. Karhunen, A. Seppänen, A. Lehikoinen, P.J.M. Monteiro, J.P. Kaipio.
Electrical resistance tomography imaging of concrete
Cement and Concrete Research 40: 137-145, 2010.


K. Karhunen, A. Seppanen, A. Lehikoinen, J. Blunt, J. P. Kaipio, and P. J. M. Monteiro.
Electrical Resistance Tomography for Assessment of Cracks in Concrete
ACI Materials Journal 107(5):523-531, 2010.

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