Issue 50

I. Dakanali et alii, Frattura ed Integrità Strutturale, 50 (2019) 370-382; DOI: 10.3221/IGF-ESIS.50.31 370 Focused on the research activities of the Greek Society of Experimental Mechanics of Materials An experimental study on restoration technique for the Acropolis of Athens: developing the experimental set-up for pull-out testing of titanium bars embedded in marble blocks Ioanna Dakanali Laboratory of Testing and Materials, Department of Mechanics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Zografou Campus, 15773 Athens, Greece dakanalioanna@gmail.com Aikaterini Marinelli School of Engineering and the Built Environment, Edinburgh Napier University, Merchiston Campus, EH10 5DT Edinburgh, Scotland A.Marinelli@napier.ac.uk A BSTRACT . Τhis work aims at investigating the mechanisms activated during the ex- traction of titanium bars from a marble volume (pull-out phenomenon), used for re- joining fragmented marble structural members at the monuments of the Acropolis of Athens. The restoration protocol includes the insertion of threaded titanium bars into pre-drilled holes in the body of the structural members. The adhesion between marble and bars is achieved by an initially liquid cementitious material. There are two main aspects on which this project focuses. Firstly, the weak link of the marble-cement- titanium complex, the marble-cement interface, is inaccessible for traditional sensing techniques. In this context, the Acoustic Emission technique is employed in order to detect failure and damages at the interior of the complex. Secondly, the specimens and the experimental procedure should simulate the same stress conditions in which all three phases within the marble-cement-titanium complex are under, while the struc- tural member is in service. For this purpose, two modified tests are proposed aiming at efficiently simulating the bars’ behavior as they are sliding through a marble epistyle. These tests provide promising results with regards to keeping the examined surface between bars and marble free from parasitic stresses caused by the experimental set-up. K EYWORDS . Marble; Stone monuments; Pull-out; Restoration; Contact interfaces; Acoustic Emission. Citation: Dakanali, I., Marinelli, A., An experimental study on restoration technique for the Acropolis of Athens: developing the experimental set-up for pull-out testing of titanium bars embedded in marble blocks, Frattura ed Integrità Strutturale, 50 (2019) 370-382. Received: 18.02.2019 Accepted: 28.05.2019 Published: 01.10.2019 Copyright: © 2019 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION he main restorative intervention on the Athenian Acropolis monuments was directed by N. Balanos in 1885. The interventions were on a grand scale and their purpose was to restore the monuments to the form that they had in classical times. The basic principle was all the destroyed ancient fragments spread around the monument to be re- T