Petros Moundoulas

THE ROLE OF RESTORATION MORTARS IN THE EARTHQUAKE PROTECTION OF KAISARIANI MONASTERY

Monuments and historical buildings are degraded as time passes due to natural ageing, environmental factors, as well as natural phenomena such as earthquakes. Their conservation and restoration thus becomes crucial in order to preserve our cultural heritage. Repointing of monuments and historical buildings is perhaps the most usual conservation action, as it restores and ensures masonry continuity in a reversible manner. However, this is accomplished only if the restoration mortar applied fulfills compatibility and serviceability criteria. In the current study, the characterization of the historical mortars of the Kaisariani monastery was undertaken and six restoration mortars were selected from literature and examined in order to assess their compatibility with the historical structure of the Kaisariani Monastery in Greece. The restoration mortars were assessed regarding their compatibility with the structural materials of the Kaisariani Monastery, as well as their impact on the earthquake resistance of the structure. A new stochastic computational framework for earthquake resistant design of masonry structural systems, based on fragility analysis and artificial neural networks was applied for the assessment of the seismic vulnerability of the Kaisariani Monastery, for three different repairing scenarios, utilizing the results of the examined restoration mortars. The results showed that a variety of restoration mortar characteristics can be achieved, an important feature, which coupled with the results of the fragility analysis for the repairing scenarios, can be utilized for the selection of the optimum restoration mortar in terms of compatibility and serviceability.

Five-Dimensional (5D) Modelling of the Holy Aedicule of the Church of the Holy Sepulchre Through an Innovative and Interdisciplinary Approach

The Church of the Holy Sepulchre (Church of the Resurrection) is one of the most important historical sites of Christianity. The current Aedicule structure is the result of various construction phases, damages and destructions, reconstructions, and protection interventions, and as such, it serves as an emblematic case study for five-dimensional (5D) modelling. The innovative and interdisciplinary approach adopted for the modelling of the Holy Aedicule of the Church of the Holy Sepulchre utilizes data from the following: (a) architectural documentation: Description of the current form and structure, as well as its evolution through the ages, based on historic documentation; (b) analysis of construction phases: The construction phases were revealed by a ground-penetrating radar (GPR) survey that was implemented within an integrated methodology, which enabled the technique to identify the various interfaces; (c) geometric documentation: Generation of a 3D high-resolution model, through an automated image-based method and through using terrestrial laser scanning; (d) materials documentation: A wide range of analytical and nondestructive techniques have been used in order to characterize the building materials and extract data for fusion in 5D modelling; and (e) 5D modelling: visualization of the historic construction phases of the Holy Aedicule of the Church of the Holy Sepulchre. The integrated modelling which, after the above analysis, includes enhanced information covering all aspects of the Aedicule structure, geometry, and materials and forms the basis for the creation of an innovative tool that induces mixed reality (MR) with the focus on the Aedicule’s structural evolution (time factor—4D) and on its materials (5D).

THE COMBINATION OF NDTS FOR THE DIAGNOSTIC STUDY OF HISTORICAL BUILDINGS: THE CASE OF KAISARIANI MONASTERY

Diagnosis is the first and most crucial step in the process of monument protection. Diagnosis demands a variety of information and can be a complicated procedure especially when dealing with historical buildings and the limitations that these induce; nevertheless when the correct methodology is followed, diagnosis can be carried out whilst minimizing the amount of samples needed, as important features are already revealed and representative samples can be located. This is achieved through a thorough and organized survey of the historical building and the implementation of various non-destructive techniques (NDTs). The in-situ optical inspection of a historical building can offer valuable information regarding the preservation state of the building as well as utility problems which might create problems for the masonry, such as humidity problems due to the movement of rainwater. Following the optical inspection, the researchers can apply NDTs on the structure as a whole, focusing however on problematic areas or areas of interest. In this study NDTs were employed in order to investigate the type of masonry structure followed by the original masonry workers, the original building materials, the different construction phases and materials, as well as non-documented conservation interventions. However, the use of one NDT alone cannot offer the required information; a combination of various NDTs is necessary in order to extract meaningful and useful results. In the case of Kaisariani monastery, presented here, after a thorough in-situ optical inspection, a variety of NDTs were applied: Ground-penetrating Radar (GRP), Infrared Thermography (IR), Fiber Optics Microscopy (FOM) and Schmidt rebound hammer. The results were analyzed and combined in order to extract results regarding the original building materials, the type of masonry construction, the preservation state of the building materials, as well as information regarding non-documented different construction phases and conservation interventions.

Design and evaluation of restoration mortars for historic masonry using traditional materials and production techniques

Cement based mortars used for historic restoration presented unsatisfactory results, due to their chemical and physico-mechanical incompatibility to original buildings. In the present research, several syntheses of restoration mortars are produced using traditional techniques and materials such as binders (aerial and natural hydraulic lime), pozzolanic additives (natural and artificial pozzolanas) and aggregates (sand and crushed brick). The technical characteristics of the mortars were determined using mechanical tests (compressive and flexural) and mercury intrusion porosimetry measurements at the time of 1, 3, 9, 15 months of curing. Water absorption measurements were performed at the time of 9 and 15 months and the total percentage of absorbed water. The aerial lime – artificial pozzolana mortar presented the best mechanical and microstructural performance. Hydraulic mortars acquired the maximum of the mechanical strength in 1 month, lime-pozzolana mortars in 3 months while aerial lime mortars continue to gain mechanical strength even in 15 months curing. Furthermore, the use of ceramic aggregates produces lightweight and elastic mortars, compatible to historic ones.

Use of thermography and fiber optics microscopy for the evaluation of railway structures in the Athens Metro in Greece

Rolling Contact Fatigue (RCF) is one of the main issues that concern, at least initially, the head of the railway; progressively they can be of very high importance as they can propagate inside the material with the risk of damaging the railway. In this work, two different non-destructive techniques, infrared thermography (IRT) and fibre optics microscopy (FOM), were used in the inspection of railways for the tracing of defects and deterioration signs. In the first instance, two different approaches (dynamic and pulsed thermography) were used, whilst in the case of FOM, microscopic characterisation of the railway heads and classification of the deterioration -- damage on the railways according to the UIC (International Union of Railways) code, took place. Results from both techniques are presented and discussed.