Ioannis Karatasios

National Center for Scientific Research Demokritos | ncsr · Institute of Nanoscience and Nanotechnology

Although organic light-emitting diodes (OLEDs) are considered a mature technology, further enhancements in their efficiency are of paramount importance for advancing their incorporation in high-quality displays and flexible, wearable, electronic devices. In this regard, we propose an innovative approach, focusing on strategic modifications to the h...

Two gallium porphyrins, a tetraphenyl GaCl porphyrin, termed as (TPP)GaCl, and an octaethylporphyrin GaCl porphyrin, termed as (OEP)GaCl, were synthesized to use as an electron cascade in ternary organic bulk heterojunction films. A perfect matching of both gallium porphyrins’ energy levels with that of poly(3-hexylthiophene-2,5-diyl) (P3HT) or pol...

Citation: Markantonis, I.; Sfetsos, A.; Vlachogiannis, D.; Kioutsioukis, I.; Michalopoulou, A.; Kilikoglou, V.; Karatasios, I. Investigation of Climate Change Impacts on the Building Materials of Archeological Monuments. Environ. Sci. Proc. 2023, 26, 120. https://doi. Abstract: Weather conditions affect the microclimate of architectural monuments....

Two gallium porphyrins, a tetraphenyl GaCl porphyrin, termed as (TPP)GaCl, and an octaethylporphyrin GaCl porphyrin, termed as (OEP)GaCl were synthesized to use as electron cascade in ternary organic bulk heterojunction films. A perfect matching of both gallium porphyrins energy levels with that of poly(3-hexylthiophene-2,5-diyl) (P3HT) or poly[N-9...

Encapsulated healing agents is a promising solution for extending the service life of critical infrastructure, providing long-term healing efficiency. This research focuses on the shell properties of cement-based spherical macro-capsules, aiming to achieve increased survivability during mixing of mortar mixtures and efficient triggering upon crack...

Lime based restoration mortars reinforced with multi-walled carbon nanotubes (MWCNTs) exhibit advanced mechanical strength, piezo-resistive properties and probably their main advantage is that they can be used as self-sensors for on-site health monitoring purposes of the restoration areas of traditional / historic structures. The present study asse...

This work presents the methodological approach followed for the study of the interaction of natural stone monuments with the local microclimate (exposure to RH, temperature alterations, wind, marine aerosol). This was implemented with the documentation of the associated weathering phenomena and the study of historic climate data of the area. The pa...

This paper combines simulation and experimental studies on the healing efficiency of spherical macrocapsules incorporated in cement mortars. A Monte Carlo simulation was applied to investigate the potential of capsules to heal cracks of different widths, depending on their size and concentration. Spherical cement-based macrocapsules were integrated...

Earth-abundant transition metal oxides deposited at room temperature with low-cost methods suitable for large area manufacturing can offer advances in many fields of energy related devices. Here we report the room-temperature deposition of a fluorine-doped tantalum pentoxide using a home-made, low-cost hot-wire deposition system. This novel tantalu...

Several methods have been proposed in the last years to evaluate the self-healing properties of concrete, and despite intense efforts towards standardization in RILEM committees and several research projects, no standards have been released yet. In the framework of COST Action SARCOS, an Interlaboratory Test (ILT) was organized to advance this topi...

In the present study, graphene oxide (GO), reduced graphene oxide (rGO) and carboxylated graphene (GCOOH) have been incorporated in lime-pozzolan-cement pastes, aiming to develop self-sensing binders that would be used for restoration applications. Τhe mechanical and electrical properties of the newly-developed nano-composite pastes were examined a...

Encapsulated healing agents comprise an emerging technology that aim to extend the service life of critical infrastructure and reduce the environmental impact of the construction industry. This paper focuses on the development and characterization of cement-based macro-capsules, made by the pan-coating technique, consisted of a reactive OPC core an...

Lime-based binders have been extensively used for restoration interventions and have successfully addressed different performance and compatibility requirements. Lime (aerial or hydraulic) is commonly used in combination with pozzolanic admixtures or cement, to comply with both, chemical/mineralogical and mechanical compatibility criteria. The goal...

This work presents the results of the measurements carried out by the Laboratory of Archaeological and Building Materials of NCSR “Demokritos” in the framework of the Interlaboratory Test (ILT) organized by SARCOS COST action CA15202. The overall aim of ILT was to assess the self-healing properties of concrete with the addition of a self-healing ag...

This paper studies the effect of clinkering temperature and duration on the production, phase evolution and microstructure of low energy Belite Calcium-Sulpho-Aluminate (BCSA) clinkers. The mineralogy and microstructure of BCSA clinker, produced in the temperature range of 1270–1340 °C and clinkering duration periods of 20, 30 and 60 min, were stud...

During the last decade, the unchecked outflow of Green House Gas (GHG) emitted by a series of different sources have led the industries to consider the environmental impact as one of the most important factors during the development of new production processes and new materials. Production cost is also a factor that companies take into consideratio...

Self-healing cement composites are considered to be an effective solution towards the enhancement of sustainability and service-life of cement and concrete structures, as well as the reduction of repair and maintenance cost. Among the several self-healing technologies, encapsulated healing agents present benefits that include healing of larger crac...

Self-healing concrete has the potential to optimise traditional design approaches; however, commercial uptake requires the ability to harmonize against standardized frameworks. Within EU SARCOS COST Action, different interlaboratory tests were executed on different self-healing techniques. This paper reports on the evaluation of the effectiveness o...

The present article demonstrates a simple, eco-friendly route for the fabrication of carbon nanotubes (CNTs) with different morphologies, including the fascinating bamboo-like structures without complex catalyst/support preparation procedures. A thermal chemical vapor deposition (CVD) technique that utilized natural pozzolan supports and a solid ca...

Titanium dioxide (TiO2) is an excellent photocatalytic material that imparts biocidal, self-cleaning and smog-abating functionalities when added to cement-based materials. The presence of TiO2 influences the hydration process of cement and the development of its internal structure. In this article, the hydration process and development of a pore ne...

Clay-based building materials have been very popular in construction and common in cultural heritage sites around the Mediterranean. The excavation of the Late Bronze Age settlement of Thessaloniki Toumba (northern Greece), revealed an abundance of this type of material with apparent preservation problems mainly caused by swelling phenomena due to...

This paper studies the morphological characteristics of calcium hydroxide nanoparticles in water based dispersions, produced following the main bottom-up (CaCl2/NaOH replacement reaction) and top-down methodologies. The work focuses on the effect of three different surfactants (TritonX-100, n-octylamine and amylamine) on the morphological character...

Historic mortars have exhibited long term durability which has been largely attributed to their self-healing properties. The aim of this work is the study of the autogenic self-healing mechanism as observed in historic mortars as well as the simulation of the phenomenon in laboratory prepared lime-pozzolan and natural hydraulic lime mortars. One of...

This work studies the morphological characteristics of four different laboratories synthesized nanolime dispersions, focusing on the characteristics of the polar dispersion medium and the increase of the water content in the final dispersion. An innovation of this research is the incorporation of distilled water that is enriched with O 2 nanobubble...

In the present study, the strength recovery of ordinary Portland cement (OPC) mortars because of the autogenic self‐healing mechanism was examined following two experimental approaches: compression tests and ultrasonic pulse velocity (UPV) measurements. The focus was given on a quantitative approach for the evaluation of the inflicted damage degree...

The aim of the present work is to study a binary paste matrix applied for the development of Cultural Heritage restoration mortars, which incorporates modified carbon nanomaterials as reinforcement. In specific, a mixture of natural hydraulic lime and metakaolin was examined. The incorporation of two different, nanomaterials was studied, namely red...

Self-healing mortars can serve as a promising solution for enhancing the efficiency of conservation interventions, extending their service life and safeguarding built heritage. In this study, the autogenic self-healing capacity of natural hydraulic lime mortars is contrasted with the autonomic self-healing capacity of the same mixture with the addi...

In this work the development of novel conservation mortars, reinforced at the nano-scale by the incorporation of carbon nanostructures was investigated. The above technology was tested for the first time in lime-pozzolan-cement ternary conservation mixtures, by incorporating multiwall carbon nanotubes (MWCNTs) in three different amounts: 0.05, 0.1...

In the present study the strength recovery of nano-reinforced cement mortars due to self-healing mechanism was examined. Graphene oxide nanoplatelets (GOnPs) were added in Ordinary Portland Cement (OPC) mortar mixtures in order to increase their resistance to crack propagation and strengthen the mixtures at the nano-scale. In order to examine the e...

Twelve ‘Japanned’ metal trays from Greece and Turkey, dated in the 19th century, were subjected to macroscopic and microscopic examination (stereoscopy, metallography, scanning electron microscopy) as well as to XRF and SEM-EDX analysis. The trays represent two stylistic types made of wrought iron either tin-plated or protected with a primer. Two w...

This work presents the analytical results of the mortars and plasters characterization from Qasr Azraq, located in the city of Azraq (north-eastern Jordan). The castle has undergone several interventions and modifications during its service life; the archaeological surveys have shown that the actual building is a medieval reconstruction of a Roman...

Based on the case of ancient theatre of Zea, in Greece, this work aims to study the geological and microstructural parameters of marls used in stone monuments, which control their durability and variable weathering response against salt damage and swelling phenomena. The ancient theatre of Zea is located very close to the coast of Piraeus, in Athen...

Synthetic resins were introduced in paintings conservation during the 1930s, as an alternative to natural resins, due to their superior resistance to degradation. Their composition usually includes a small amount of additives, such as titanium dioxide. The objective of this work is to study the effect of TiO2 additive on the durability of Paraloid...

Performance characteristics of mortars are governed by the type of binder, type and grain size distribution of aggregates and their mix proportions. Aiming at parametric optimization of NHL restoration mortars, this study discusses the effect of physical and geometrical properties of aggregates on fresh and hardened mortars, tested after 28 days of...

This work studies the polymerization process of four different commercially available silicon-based polymers and their consequent effect on surface tension and water transport properties of natural stones used in architectural monuments, essential for modeling and predicting the durability of natural stones against weathering action of aqueous solu...

Increased proliferation of antimicrobial-resistant and new strains of bacterial pathogens severely impact current health, environmental, and technological developments demanding for design of novel, highly efficient antibacterial agents. Ag, Cu monometallic and Ag/Cu bimetallic nanoparticles (NPs) were in-situ grown on the surface of graphene, whic...

Mortars are known for their ability to heal their defects in an autogenic way. This phenomenon is expressed by the filling of microcracks by secondary products, restoring or enhancing the material’s performance. Parameterization of self-healing phenomenon could be a key factor for the enhanced sustainability of these materials in terms of reduced r...

The monitoring of performance characteristics of resins was always an issue for the conservation community, since the stability of the art objects depends on the service life of conservation materials used. Among the resins commonly applied in the field of paintings conservation, four of the most popular ones, Paraloid B72, Primal AC33 (acrylic pol...

A multilayered ceramic membrane bearing a zirconia separation layer having a nominal pore diameter of 3 nm was modified by chemically grafting a silylated ionic liquid (IL) on the porous zirconia surface and became catalytically active for oxidation of CO by effectively growing ultra-small gold nanoparticles (AuNPs) which served as the active phase...

A novel biomimetic nanocomposite was synthesized by the sol gel process in order to reduce the main drawbacks of tetraethoxysilane (TEOS)-based consolidants, such as crack formation upon the drying process and insufficient bonding to carbonaceous substrates. The reaction route involves the addition of a colloidal solution of synthesized nano-calciu...

A novel biomimetic nanocomposite, comprised of amorphous silica and calcium oxalate, has been efficiently synthesized by incorporating materials of low toxicity and cost, imitating a stable binary system occurring in well-preserved areas of monuments, plant biomineralization and the industrial processing of sugar. A simple two-step and cost-effecti...

This paper reports on the technological study of a unique group of ceramic beehives, discovered at the archaeological site of Kastraki on Agathonisi Island in Greece. This is an important Late Hellenistic site, situated just off the Ionian coast near Miletus. Beehive terracotta material exhibits a porous, rough structure, fired at low temperatures...

Aggregates are an important ingredient of mortars as they can be a decisive factor for their performance just as much as for their production cost. This study aims to discuss the use of sand from local deposits in the design of restoration mortars in terms of compatibility with original building materials, along with the optimization of mix proport...

This paper presents the results of a systematic investigation of the pozzolanic activity of different types of ceramic admixtures, as a function of their chemical composition (calcareous, non-calcareous) and vitrification state. The study was carried out on experimental ceramic-lime mixtures. The evaluation of the reactivity of the different cerami...

A novel biomimetic nanocomposite composed of amorphous silica and calcium oxalate has been efficiently synthesised by incorporating materials of low toxicity and cost, imitating a stable binary system occurring in well-preserved areas of monuments, plant biomineralisation and the industrial processing of sugar. A simple two-step and cost-effective...

Natural hydraulic limes are used as an alternative to cement-based binders in mortars and renders for the repair and maintenance of historic structures as well as in new building. This paper discusses the role of the binder type, the grain size and the packing density of aggregates on the physico-chemical and mechanical characteristics of hydraulic...

A substantial number of glass artifacts, mainly beads, have been found among the rich burial offerings of the Mycenaean cemeteries in the municipalities of Ialysos, Kamiros, and Southern Rhodes. A chunk of raw glass and a stone mold for manufacturing jewelry, uncovered at the settlement of Trianda, near Ialysos, offer strong evidence for a secondar...

In the present study fragments of pyrotechnical ceramics used in Bronze Age metallurgy were tested for their heat transfer properties. For the estimation of their thermal conductivity a simple stationary method was used, based on the Lee's disc method. The results were assessed in relation to microstructure and porosity of the ceramic matrix. Furth...

The influence of environmental conditions, in particular temperature, on the performance of adhesives joining different archaeological ceramic fabrics is assessed in laboratory conditions. Different types of model ceramic fabrics were manufactured and joined with commercially available adhesives, which are commonly employed in the conservation of a...

This work reports on the technological study of a unique group of ceramic beehives, discovered at the archaeological site of Kastraki, Agathonisi island (Tragaia) in South-east Aegean. Kastraki is an important late Hellenistic site, situated just off the Ionian coast, near Miletus. The island has a rich history in craft production as witnessed from...

The micro-structural evolution of a lime-pozzolan system, during hydration, was studied by 1 H Nuclear Magnetic Resonance (NMR). The hydration process was monitored for a period of 1 year by 1 H NMR spin-lattice relaxation measurements, performed in a portable magnet. The development of the hydration was also examined by scanning electron microscop...

The development of strength in conservation mortars is of particular significance for new synthesized lime-based mixtures in terms of practical application, performance requirements and renovation cost of built monuments. In this work, the effect of relative humidity (RH%) on the strength characteristics of lime-natural pozzolan mortars was studied...

1H nuclear magnetic resonance (NMR) relaxation is applied to lime–pozzolan mixtures to monitor in real-time the hydration and porosity evolution during setting. The hydrated products formed during the setting of these mixtures are similar to those formed in hydraulic binders (e.g. cement and natural hydraulic limes). In this work, we demonstrate th...

The natural pozzolans studied are commercial products and come from the volcanic islands of Milos and Kimolos as well as North Greece mainland. The materials were characterised mineralogically and chemically by XRD and SEM/EDX respectively, while their reactivity with calcium hydroxide was studied through a pozzolanic activity test. In addition, fi...

In this work, titanium dioxide (TiO2) has been used as an additive in lime binder (Ca(OH)2), in order to benefit from its photocatalytic properties and study both the photocatalytic properties of the produced mixtures and the effect of photocatalytically produced carbon dioxide on the carbonation process of lime. TiO2 was added in three different p...

This paper deals with the evaluation of different consolidation treatments of the excavated foundation of the Poseidon Temple in Poros island, Greece, made by a friable, low strength type of local limestone. Four types of commercial products have been studied in the laboratory, grouped in three categories: inorganic consolidants, acrylic emulsions...

The present case study concerns the technology of Byzantine wall paintings from the Mani Peninsula, Greece. An assemblage of 12 Byzantine churches, constructed in the tenth to fifteenth century, was included in an initial analytical survey. Two random samples of wall paintings were taken in each monument in order to study their micro stratigraphy a...

This work studies the effect of barium hydroxide on the sulphate-resistance of lime-based mortars when used as an additive material to the lime binder. The overall aim of the work is to study the potential of barium hydroxide in producing a mixed binder with lime, which is able to fix the sulphate ions, block the diffusion of sulphate solutions and...

This paper presents the effect of barium hydroxide on the setting mechanism of lime-based conservation mortars, when used as an additive material. The study focuses on the monitoring of the setting process and the identification of the mineral phases formed, which are essential for furthering the study of the durability of barium mixtures against c...

This study presents the results of the physico-chemical characterization of original mortars and plasters and the evaluation of the repair ones prepared with natural hydraulic lime (NHL) as binding material and siliceous sand and crushed brick as aggregates. The repair mortars were applied in restoration works of a historic masonry in Crete, Greece...