Rehabilitating heritage buildings, monuments and cultural architectures is quite challenging as any efforts must conform to their architectural and constructive features. Generally, rehabilitation projects require a detailed collection of the relevant information regarding the features and constructive techniques of the buildings. However, such information is lacking as reliable sources such as written documents were long lost. Today, testing is one commonly used method to obtain such information. Unlike destructive tests that involve removing samples for investigations, non-destructive tests (NDTs) respect the characteristics and integrity of the ancient buildings because they provide the overall image of the area under investigation instead of samples. Since NDTs are widely preferred over destructive tests, there is a need to obtain high-resolution images to ensure useful data.
Several NDTs have been proposed to investigate heritage and ancient buildings. Geophysical methods, for example, are high-resolution NDT use in various civil engineering projects, including those in limited or restricted areas. They include Seismic Tomography, Ground Penetrating Radar (GPR), and electrical resistivity tomography. GPR is the most widely used to investigate materials and construction characteristics of different structures due to its flexibility and ability to provide high-resolution images. However, considering the many challenges faced in the rehabilitation and maintenance of heritage facilities, there is a need to adopt multimethod approaches for obtaining accurate and reliable information regarding the facilities under investigation.
It is noteworthy that combining different geophysical methods is good for solving different problems because the methods tend to complement each other to provide full information about the problem under investigation. Herein, Professor Manuel Matias and Professor Fernando Almeida from University Aveiro, in collaboration with Professor Rui Moura from the University of Oporto and Engineer Nuno Barraca from GeoAviz investigated the constructive elements (specifically columns and walls) of a late fourteenth century UNESCO monument, Batalha Abbey, using a combination of GPR and Seismic Transmission Tomography. The original research article is currently published in the journal, Construction and Buildings Materials.
Briefly, the building was constructed in the late fourteenth century using local limestone, which has deteriorated both physically and chemically with time. Even though some historical sources provide information regarding the building techniques used in constructing the main structures of the monument, there are no proofs to support those claims. Therefore, this work focused on bridging the existing information gap by investigating the bedrocks and foundations, anthropic structures, and pathologies outside the building. They also characterized the inner structures of the columns and walls and materials used to construct Batalha Abbey.
The authors observed that the two methods complement each other, thus providing more information about the constructive elements of Abbey. For instance, GPR provided high-resolution images but sometimes poor images of the interior of the structural elements, while Seismic Tomography, on the other hand, provided quality images on the full interior areas. Additionally, GPR provided an accurate definition of the boundaries and interfaces of the seismic models, while Seismic Tomography provided information regarding the composition of the walls and columns. Even though the combination of Seismic Tomography and GPR is less common, the authors proved its suitability and complementary in investigating monuments and building structures in general.
In summary, a combination of Seismic Tomography and GPR was used to characterize the inner structures and materials of the walls and columns of Batalha Abbey, a late fourteenth-century building. For the first time, the study provided valuable information on the internal structures of the walls and columns of Abbey easily and most effectively with minimal disturbance to the building and visitors. The combined methods provided good images and a detailed understanding of the constructive elements and spatial distribution of the materials used to construct the monument. In a statement to Advances in Engineering, Professor Manuel Matias explained their study will pave the way for using different high resolution NDT methods for assessing various buildings as well as opening the path for 3D research and investigations.
Reference Matias, M., Almeida, F., Moura, R., & Barraca, N. (2021). High resolution NDT in the characterization of the inner structure and materials of heritage buildings walls and columns. Construction And Building Materials, 267, 121726. ern
Matias, M., Almeida, F., Moura, R., & Barraca, N. (2021). High resolution NDT in the characterization of the inner structure and materials of heritage buildings walls and columns. Construction And Building Materials, 267, 121726.