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,Aikaterini Marinelli

doi:10.3221/igf-esis.50.31

Abstract

This work aims at investigating the mechanisms activated during the extraction of titanium bars from a marble volume (pull-out phenomenon), used for rejoining 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 structural 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.

Highlights

The main restorative intervention on the Athenian Acropolis monuments was directed by N
The aforementioned technique is based on some basic principles: i) Reversibility, ii) Minimization of the interventions to the extent that guarantees protection of the authentic material from further damage and iii) Compatibility between the materials used for the restoration and the authentic ones [3]
C urrent research in the field of restoration of the Acropolis monuments addresses the quality of adhesion between marble and reinforcing bars used to rejoin fragmented elements

Summary

Introduction

The main restorative intervention on the Athenian Acropolis monuments was directed by N. The aforementioned technique is based on some basic principles: i) Reversibility (if needed, the monument could be brought to its state prior to the intervention), ii) Minimization of the interventions to the extent that guarantees protection of the authentic material from further damage (for this reason the number of titanium bars required by the connection’s design, should be the smallest possible) and iii) Compatibility between the materials used for the restoration and the authentic ones [3]. The bar and the surrounding concrete are under tension (bending beam) while in pull-out tests, the bar is in tension and the concrete around it is in compression [4] For this reason, several alternative test designs were proposed (Fig.1(b, c))

Methods

Results

Conclusion