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Materials characterization

Keywords: NDT, monitoring, effective stress, effective strain, Poisson ratio
Fig. 1. View of the LISG laboratory (Colla).
Materials characterization - Fig. 2
Fig. 2. Monitoring of physical-mechanical tests using acoustic emission sensors or DIC (Colla).
Fig. 3. Compressive test on straw bale (Molari).
Materials characterization - Fig. 4
Fig. 4. On-site mechanical characterization of historic mortars by micro-destructive testing (Colla).

The research in this area can be divided into two main blocks:

- the mechanical characterization with convectional procedures of non-convectional materials. In particular, non-convectional building material like straw bale….. are tested to understand the mechanical properties under static and dynamic loads.

- the development of innovative and unconventional procedures and testing techniques to be performed in the laboratory and on site for studying building materials, e.g. mortars, bricks, wood, … with the aim of determining their mechanical and physical properties, such as compression, shear or tensile strength, the elastic modulus, the capillary rise velocity, etc

In particular special procedures for testing single materials samples which may have irregular shapes or portions of structural elements taken on-site, also on historic and/or earthquakes damaged structures. A further innovative development in the procedures for the mechanical characterization of materials and assessment of the structure - environment interaction, is represented by the coupling of mechanical tests with non-destructive diagnostic techniques (sonic tests, IR thermography, digital correlation of images, acoustic emission ...) or monitoring systems, also wireless (e.g. potential embedded sensors for salt content monitoring in masonry materials).

On-site, minimally invasive testing equipment (e.g. penetrometers for mortars and wood, hammers …) and combined procedures are used to characterize the materials and assess the health-state of the structures.

Main publications

Testoni, N., De Marchi, L., Marzani, A. (2016) Detection and characterization of delaminations in composite plates via air-coupled probes and warped-domain filtering, Composite Structures, 153, 773-781.

Maraldi M., Molari L., Regazzi N., Molari G. (2016) Experimental Characterization of Straw Bales Mechanical Behaviour, submitted to Biosystem Engineering.

Marzani, A., De Marchi, L. (2013) Characterization of the elastic moduli in composite plates via dispersive guided waves data and genetic algorithms, Journal of Intelligent Material Systems and Structures, 24 (17), 2135-2147.

Gentilini C., Franzoni E., Bandini S., Nobile L. (2012) Effect of salt crystallisation on the shear behaviour of masonry walls: An experimental study, Construction and Building Materials, 37, 181-189.

Ferretti E. and Bignozzi M.C. (2012). Stress and Strain Profiles along the Cross-Section of Waste Tire Rubberized Concrete Plates for Airport Pavements, Computers, Materials, & Continua (CMC) 27(3), 231-274.

Ferretti E. (2012). Shape-effect in the effective laws of Plain and Rubberized Concrete. Computers, Materials, & Continua (CMC), 30(3), 237- 284.

Ferretti E. (2012). Waste Tire Rubberized Concrete Plates for Airport Pavements: Stress and Strain Profiles in Time and Space Domains. Computers, Materials, & Continua (CMC) 31(2), 87-112.

Colla C., Gabrielli E., Krueger M. and Lehmann, F., (2012). Experience of acoustic emissions of masonry. Proc. of EWCHP 2012, Cultural Heritage Preservation, Kjeller, Norway, September 24th -26th, ed. E. Dahlin, NILU –Norwegian Institute for Air Research, ISBN 978-82-425-2525- 3, 207 - 215.

Gabrielli E., Marani F. and Colla C. (2012). Ir thermography to compare the evaporation fluxes in brick masonry. Proc. of EWCHP 2012, Cultural Heritage Preservation, Kjeller, Norway, September 24th -26th, ed. E. Dahlin, NILU – Norwegian Institute for Air Research, ISBN 978- 82-425-2525-3, 216 - 223.

Rajcic V. and Colla C. (2011). Correlations between destructive and four NDT techniques tests on historic timber elements. Proc. of EWCHP 2011, Cultural Heritage Preservation, Berlin, Germany, September 26-28, ed. M. Krüger, Fraunhofer IRB Verlag, ISBN 978-3-8167-8560, 148 - 155.

Colla C. and Pascale G. (2010). Prove non distruttive e semidistruttive per la caratterizzazione delle murature della torre Ghirlandina di Modena. In La torre Ghirlandina – storia e restauro, R. Cadignani (a cura di), Roma, 218-227.

Ferretti E. and Di Leo A. (2008). Cracking and Creep Role in Displacements at Constant Load: Concrete Solids in Compression. Computers, Materials & Continua. vol. 7, pp. 59 - 80 ISSN: 1546-2218.

Research projects

SMooHS – Smart Monitoring of Historical Structures, Unità di Bologna, European Research project ENV.2007.