Journal of Cultural Heritage xxx (2013) xxx.e1–xxx.e6
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ptimization of compatible restoration mortars for the earthquake protection ofagia Sophia
ntonia Moropoulou ∗, Asterios Bakolas , Petros Moundoulas , Eleni Aggelakopoulou ,ophia Anagnostopoulouational Technical University of Athens, Department of Chemical Engineering, Section of Materials Science and Engineering, 9, Iroon Polytechniou Street, 15773 Zografou, Athens,reece
a r t i c l e i n f o
rticle history:eceived 20 December 2012ccepted 16 January 2013vailable online xxx
eywords:estorationortars
a b s t r a c t
In the present work, optimization of restoration mortars was performed on the basis of reverse engi-neering approach. The examination and selection of raw materials and the production of a number ofmixtures with different ratios of binder/additives/aggregates and gradations were carried out. The selec-tion of these materials was based on the examination of the historic mortars of the monument. In orderto evaluate mortar mixes during setting and hardening, thermal analysis (DTA-TG), mercury porosimetryanalysis and mechanical tests (compressive, flexural) were performed. The results indicate that mortarswith hydraulic lime as binding material being admixed with crushed brick, present better behaviour
arthquakerotectiononument
than those with aerial lime, or lime-cement, or lime-pozzolanic additives. The results are in accordancewith the acceptability limits defined by the investigation of the historic ones. The results obtained fromtwo-phase production permitted the selection of proper mortar mixtures and their pilot application ona historic masonry of Hagia Sophia, which is going to be evaluated on time as far as compatibility andmortars good performance on the masonry are concerned. Moreover, concrete specimens were producedand examined for the earthquake protection of Haghia Sophia monument.
. Introduction
The present work focuses on the preparation and evaluationf optimized restoration mortar mixtures which will be able toespond to intensive environmental loads, to continuous mechani-al stresses and be compatible to the original structural units of theasonry. Structural studies to determine the earthquake worthi-
ess of Hagia Sophia have proved that the monument’s static andymamic behavior depends strongly on the properties of masonryaterials (stones, bricks, mortars, etc.). Previous works led to the
lassification of the characteristic crushed brick-lime mortars ofagia Sophia to the category of hydraulic composites, explain-
ng the good performance of structural units [1]. Investigations onrushed brick-lime mortars of Hagia Sophia led to the conclusionhat the examined mortars present various production technolo-ies with binder/aggregate ratios varying from ¼ to ½ per volume2]. Low ratios (¼) are probably attributed to the washing out of
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alcite due to weathering [3] and not to specific Byzantine processechnologies. Binder, that comprises the mortar matrix, presentsydraulic character partially attributed to the binding materials
and partially to the lime-crushed brick interactions at the inter-face [4]. Moreover, crushed brick grain size influences directly itshydraulic reactivity, as well as its physicomechanical properties[5]. In previous work, Transmission Electron Microscopy providedvaluable information concerning the development between thecrystalline phases of calcite and the dispersed ceramic fragments ofan amorphous sheet structure calcium alumino-silicate gel forma-tion. The presence of these amorphous phases comprises a matrixof hydraulic nature, which allows energy absorption [6]. The dura-bility of the examined historic composites and their compatibilityto the structural units are attributed to the quality of raw materials,their physicochemical and mechanical properties and the produc-tion technologies.
Consequently, a reverse engineering approach has to be adoptedfor the reproduction of historic mortars [7]. Moreover, an integratedinvestigation should be attempted [3], concerning structural andmaterials aspects, in order to develop and evaluate proper conser-vation materials.
2. Reverse engineering as a methodology for the
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production of compatible restoration mortars
The first step of the above methodology is the charac-terization of historic mortars, the selection of raw materials
nd finally the general mortar mixture directives. With theseirectives preparation of restoration mortars with differentinder/additives/aggregates ratios, are tested. The evaluation ofestoration mortars properties is required for the specification ofhe technical characteristics of the mortars pastes and during theetting and hardening. The following step is the optimization ofestoration mortar mixes based on the data provided as mentionedbove and selection of the proper production process. The finalut most important step is the pilot application for the evalua-ion of restoration mortars on masonry scale by non-destructiveechniques [8].
.1. Experimental procedure for the evaluation of restorationortars mixtures during setting and hardening – First phase
roduction
In order to evaluate the various mortars mixtures dur-ng setting and hardening, the following measurements wereerformed: Differential Thermal and ThermoGravimetric Anal-sis (DTA - TG) (Netzsch, STA 409 EP) in order to estimatehe hardening rate and the development of chemical phases,
ercury Porosimetry (Posimeter 2000, Fisons Instruments) inrder to evaluate microstructural characteristics during harden-ng and Mechanical Strength Tests (DIN 18555 September 1982)n order to estimate mortars strength acquired during hardening9].
.1.1. Microstructural and mechanical evaluationMixtures with natural hydraulic lime and lime putty/pozzolanic
dditives presented high mechanical strengths either with sandggregate or mixed aggregates of sand and crushed brick at theime of 9 months of curing.
As far as microstructure is concerned, a correlation betweenicrostructural parameters and mechanical strength was detected.uring hardening there is an increase in specific surface area alongith a decrease to the average pore radius that leads to increasedechanical strength values. Total porosity ranges between 30–48%ith hydraulic lime mortars presenting the lower values, which
eads to more cohesive materials. Bulk density values are relativelyow, especially for mixtures with mixed aggregates due to the pres-nce of crushed brick [10].
.1.2. Thermal analysis evaluationMixtures with natural hydraulic lime as binder showed high
ate of chemical phases evolution, which is almost completedfter 3 months. Structurally bound water is detected even fromhe first 15 days of hardening. The development of hydraulichases contributes to the mechanical strengths that mortarscquire.
Lime mortars presented the slowest rate of chemical phasesvolution, which is not completed even after 9 months. The rate ofardening is very slow until the third month, and becomes fasterntil 9 months.
The examination of mortars with pozzolanic additives showedhat the evolution of chemical phases is slower than that ofydraulic lime mortars. The structurally bound water (∼1.00%)
ndicates the presence of ceramic powder and earth of Milos dueo the hydraulic phases.
Cement mortars of this category, due to the low content ofement, perform similar results as lime putty mortars. The signif-cant difference is that in the evaluation of lime putty – cement
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ortars structurally bound water is detected. Low percentage ofement leads to the separation of binders [11] while high cementontent has to be avoided given the incompatible microstructuref the material to the original units [12].
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2.2. Optimization – Second phase production
Based on the results obtained from the first phase production ofrestoration mortars, an optimization phase followed, concerninga thorough investigation of the parameters controlling mechanicalstrengths along with microstructural characteristics. At this point ofresearch different mortar mixtures were studied, according to thetypical mortar categories declosed from the investigation of historicones (typical lime, hydraulic lime, lime – pozzolana mortars).
2.2.1. Optimization of raw materialsA number of raw materials (lime putty, lime powder, NHL-2,
earth of Milos, brick powder, sand, crushed brick) were tested usingthe following techniques (DTA-TG, XRD, XRF, Mercury IntrusionPorosimetry, pozzolanicity test, active silica test, chemical analy-sis). The final selection of raw materials is based on the specificrequirements that the materials should fulfill [9].
The materials selected for the production of mortar mixturesat the second phase and their basic characteristics are presentedbelow:
Lime putty presented high percentage of Ca(OH)2 and its colloidnature considered being a desired characteristic. The free watercontent of lime putty and its bulk density were approximately 58%and 0.825 g/cm3, respectively.
Lime powder was also tested for reproducibility reasons. Limepowder presents a higher percentage of Ca(OH)2 (88%) than limeputty and low percentage of CaCO3 (∼5.5%).
For the production of hydraulic mortars, natural hydraulic lime(NHL-2 according to CEN-prEN 459-1) was used.
Earth of Milos was examined as a pozzolanic additive. The per-centage finer than 64 �m is about 88%. From the pozzolanicity test,compressive strength was about 6 N/mm2. The total percentage ofsilica is about 65%, and the relative percentage of active silica is 20%,while XRD analysis reveals the high content of amorphous glassyphases.
Being an artificial pozzolana, brick powder was produced bycrushing and grinding compact bricks. Pozzolanicity test showedcompressive strength values up to 6.2 N/mm2, while it is finer thanearth of Milos (percentage finer than 64 �m is about 94%). The totalpercentage of silica is about 58%, and the relative percentage ofactive silica is 20%.
Washed river-sand, yellow-colored was used from the river Stri-monas. Chemical analysis reveals its silicate nature. It presents awide grain size distribution ranging between 0/1 mm.
The crushed brick comes from Thessaloniki-Macedonia. Itpresents a grain size distribution ranging from 1/6 mm. Themicrostructural characteristics of the brick were examined show-ing values of total porosity ∼28% and bulk density 1.89 g/cm3.
2.2.2. Optimization of mortar mixture directivesThe most important parameter is the content of the binder in
the mixture and the binder/pozzolanic additive ratio. Generallyan increase of 5–10% of the added binding material was followedaiming to augmented mechanical strengths and to the plastic-ity of mortar pastes. Furthermore, investigations on the optimumlime/pozzolanic additive ratio led to a proportion of 1:1 augment-ing at the same time the hydraulic nature of the mortar.
In all the mixtures studied at the optimization phase a standardmixture of aggregates (sand and crushed brick) was used, in orderto produce lightweight and elastic mortars simulating the historicones. The proportions of sand and crushed brick used in the mixturewere determined in a way that the obtained gradation curve would
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be wide and sigmoid with a percentage of voids relevant to thepercentage of the binding material added. The above-mentionedcriteria led to an aggregate mix of 65% sand (0/1 mm) and 35%crushed brick (1/6 mm).
Preparation of the pastes took place at the laboratory by these of a mixer. Binding material along with pozzolanic additiveaccording to the mixture prepared) are being admixed with theppropriate content of water, as it has been previously determinedy the testing of pastes (flow test). Aggregate materials (sand andrushed brick) are being premixed and then gradually added to theixture.The pastes are being moulded immediately after their prepa-
ation to appropriately prepared moulds according to the DIN164. Immediately after the preparation of the specimens, mouldsre covered with glass sheets and kept at 20 ◦C and 100% rela-ive humidity for one day. From the second day the specimensre stored under controlled conditions of 20 ◦C and 55% relativeumidity.
In order to evaluate the mortar synthesis, the experimental pro-edure of the first phase was followed.
.2.3. Results
.2.3.1. Evaluation of microstructural characteristics. Theicrostructural characteristics of all mortars tested are shown in
able 1. The microstructural investigation shows improvement inll parameters tested, and especially on the total porosity, wherehe results are in absolute agreement with the acceptability limitsefined by the investigation of the historic mortars [8], althoughhe microstructural distribution is controlled by the crushed brickaggregate). The values for density show lower values from thosef the first syntheses.
.2.3.2. Evaluation of mechanical characteristics. The results fromhe mechanical strength tests are shown in the Table 2.
The results indicate improvement in all mixtures tested inomparison to the mixtures of the first phase production. Mor-ars with lime powder as binder presented better behavior thanhose with lime putty. From mixtures with pozzolanic addi-
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ives those with ceramic powder showed better results. Hydraulicime mortars presented the best behavior among all. The resultseed to be confirmed by the tests of 6 and 9 months of cur-
Combined evaluation of the data obtained from the first andsecond phase production of restoration mortars ameliorates theproper optimized mortar mixtures.
Mortars with hydraulic lime and lime powder – ceramic addi-tive showed the best behavior among all mixtures tested as far asmicrostructural characteristics and mechanical strengths are con-cern.
The use of lime powder in mixtures provided better repro-ducibility. Furthermore, results after 3 months indicate thatmortars with lime powder exhibit better microstructural andmechanical characteristics than lime putty mortars.
Mixtures with natural hydraulic lime and lime powder alongwith ceramic powder as pozzolanic additive present the bestmechanical strength of all, as well as satisfactory workability andrates of setting.
The presence of crushed brick to all mixtures led to the produc-tion of lightweight mortars simulated the historic ones.
Mortars with hydraulic lime mixed with crushed brick pre-sented the highest mechanical strengths than those with aerialbinder that presented the lowest values. Furthermore, comparisonsbetween first phase production restoration mortars and optimizedmixtures showed that the critical factor for the improvement ofmechanical strengths was the increase of the binder to the mix-tures, along with the gradation of the aggregates.
Experimental results at the time of 6 and 9 months need to bededuced for the thorough evaluation of the mixtures. Nevertheless,the 3 months results indicate that the optimization of mixtures issuccessful.
Combined evaluation of all results obtained from both phases ofproduction led to the selection of proper restoration mortars thatapplied on pilot scale at the Hagia Sophia monument.
3. Pilot application
3.1. Application area
According to the architectural imprint of the monument, asshown in Fig. 3, the application area is located on the perimet-ric arcade of the atrium, at the North/West section of the outernarthex of Hagia Sophia, which was built on the 6th century, accord-ing to the authorities of the monument. The main characteristicof the structure is the different conservation interventions thathave taken place through the coarse of time. Incompatible restora-tion materials (i.e. cement) have caused decay problems on the
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masonry, which were also detected (Figs. 1 and 2).The presence of rising dump was obvious from the macroscopic
observations on the masonry, along with the extended decay of oldmortars surface due to the polluted atmosphere.
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xxx.e4 A. Moropoulou et al. / Journal of Cultural Heritage xxx (2013) xxx.e1–xxx.e6
m
b
3
s
•
•
•
Bmd
w1i
Fig. 1. Aspect of the work field before the application.
An extended vertical crack was observed along bricks and jointortars, on the level of the application area.Joints were cleaned by mechanical means and washed out
efore the pilot application.
.2. Mortar mixtures and application technique
The mortar mixtures that were applied on the pilot masonryurface are given above:
hydrated lime powder mortar with ceramic powder as pozzolanicadditive and mixed aggregates of sand and crushed brick;hydraulic lime mortar with ceramic powder as pozzolanic addi-tive and mixed aggregates of sand and crushed brick;hydrated lime powder mortar with artificial pozzolanic additiveand mixed aggregates of sand and crushed brick.
Mortar components were mixed carefully at the University ofogazici. For the in situ application, the given surface of the pilotasonry was divided in three vertical zones, at each one of them a
ifferent mortar mixture was applied.The depth of the applied mortars was approximately 5 cm,
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hile the distance from the exterior surface of the bricks was–2 cm. Consequently, the thickness of the mortar was approx-
mately 3–4 cm and its height 5–6 cm. During the application,
Fig. 2. Extended vertical crack on the masonry (decayed joint mortars).
Fig. 3. Grain size distribution of aggregates compared to the Hagia Sofia HistoricConcrete.
restoration mortars were compacted in two layers and each of themwas allowed to harden for approximately half an hour before thenext layer was applied, so as to minimize the overall shrinkagecrack of the paste. Moreover, after the application the joint mor-tars were tooled to match, at some extent, to the texture of masonrytraditional mortars.
4. Concrete
Traditional types of materials were used for the concrete pro-duction in order to assure the physicochemical compatibility toauthentic materials. Lime powder (Ca(OH)2: 89%, CaCO3: 5%, CaOHellas) and natural hydraulic lime (NHL3.5-Z according to CEN EN459-1) were used as binding materials along with cement (I/45,TITAN Cement Industry) for comparative reasons.
The pozzolanic additions used were either earth of Milos (EM)or metakaolin, an artificial high reactive pozzolanic addition.
The aggregates used consist of a mixture of sand (calcitic andquartz origin) and ceramic fragments. The former has already beendetected in historic mortars samples resulted to the production oflightweight, low-modulus of elasticity materials, due to its lowerbulk density in respect to the sand aggregates.
In order to achieve an analogous grain size distribution to HagiaSophia historic one 4 types of aggregates were mixed:
• sand of quartz origin with the following fractions of grain size(0.063–0.5 mm, 0.5–1 mm, 1–2 mm, 3–6 mm);
• sand of calcitic origin with a grain size fraction of 2–4 mm;• coarse calcitic gravel with a grain size fraction of 2–16 mm;• ceramic Fragments disposed in two grain size fractions (0–8,
2–16 mm).
Fig. 3 presents the grain size distribution of aggregates mixescompared to the Hagia Sofia historic concrete.
Table 3 states the materials mixing proportions as percentageper weight (%, p.w.) for the concrete preparation. The amount ofwater that was added in the syntheses was determined throughthe criteria of slump cone test. The acceptable value of slump wasdetermined as lower than 40 mm, according to EN 12350-2 (TestingFresh Mortar – Part 2: Slump Test). In that way, the amount of waterwas the minimum that could be added and the syntheses presentedalmost the same consistency.
Once the concrete was prepared, it was molded in moulds of10 × 10 × 50 cm, using a vibrator table with the intention of accom-
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plishing a sufficient compaction. Then, they were stored in a moistcuring chamber of relative humidity RH > 95% and temperatureT = 20 ± 2 ◦C for 7 days in the case of concrete 3–9 and 14 days in thecase of concrete 1–2. Afterwards, they were demoulded and stored
n a chamber of standard conditions (RH = 50 ± 1%, T = 20 ± 2 ◦C) tillhe testing day.
. Results
In general, all the concrete syntheses present a uniform distri-ution of the aggregates in the whole concrete mass and a goodomogeneity in binder matrix. Furthermore, it could be noticedhat a better adhesion of the binder matrix to the aggregates isccurred in the case of ceramic aggregates than to the gravels/sandggregates.
Table 4 presents the apparent density values for the concrete in2 months of curing time. The minimum value is reported for con-rete synthesis 5 (∼1.56 g/cm3) where only ceramic fragments aresed. On the other hand the maximum value is stated for concreteyntheses 1 (∼1.95 g/cm3) where the aggregates of sand and gravelre used as aggregates. Furthermore, concrete syntheses 9 exhibitsow value of apparent density (∼1.63 g/cm3), fact that could bettributed to the use of a high percentage of hydrated lime and
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he use of ceramic fragments up to 50% in the total fraction ofggregates.
Figs. 4 and 5 report the flexural and compressive strength dataor concrete at the time of 1, 3, 6 and 12 months of curing. Regarding
ig. 4. Compressive strength for concrete at the time of 1, 3, 6 and 12 months ofuring.
Fig. 5. Flexural strength for concrete at the time of 1, 3, 6 and 12 months of curing.
the effect of binder nature to concrete mechanical strength it couldbe noticed that in the case of using EM as a pozzolanic addition,the concrete presents low values of compressive strength (6.2 &5.8 MPa for the syntheses 1 & 2, respectively at 12 months of cur-ing time) and flexural strength (0.44–0.54 MPa). This fact could beattributed to the low reactivity of this pozzolanic addition regardingthe Ca(OH)2 consumption. Moreover, in the case of EM concrete themaximum value of compressive strength is gained by the time of6 months whereas the flexural strength increases till 12 months ofcuring time.
On the other hand, MK concrete exhibit a wide range of compres-sive strength (8.4–26.5 MPa) and flexural strength (1.42–2.82 MPa)values at 12 months of curing time, fact that could become a valu-able tool for the design of restoration concrete, taking into accounteach time the historic structure’ s specific characteristics.
MK concrete syntheses (3–6) present high values of mechani-cal strength. By the time of 3–6 months, MK concrete presents themaximum value of mechanical strength while beyond this periodit is decreased.
By the time of 1 month, these mortars gain the 90–100% of thefinal compressive strength and the 79–100% of the final flexuralstrength and, therefore, it could be used as a pozzolanic additionfor restoration mortars/concrete production in order to amelioratethe early strength of hydrated lime mortars.
Comparing the concrete syntheses 3, 6 and 9 as far as the 3, 4and 5, it could be figured that by increasing the lime percentageand the ceramic fragments percentage, the mechanical strength isreduced.
Almost all MK concrete syntheses (concrete 3, 4, 5, 6) presenttoo high values of compressive strength compared to the one oftraditional handmade bricks of brickwork masonry. Regarding themechanical compatibility, only concrete 9 presents a sufficientvalue of compressive and flexural strength at 12 months of curing.
Concrete produced by mixing hydrated lime and cement (con-crete 7) exhibit an increase in compressive strength values tillthe time of 12 months whereas a decrease in flexural strength isobserved from 6 to 12 months. Regarding the mechanical behav-ior of hydraulic lime concrete, it is observed that the strength isincreased till the 12 months of curing time. Though, both synthe-ses present too high values of mechanical strength regarding thestrength of traditional structural materials.
Fig. 6 presents the data of static and dynamic (estimated byultrasonic method) modulus of elasticity for concrete. In general,it could be said that the modulus of elasticity values are in accor-dance with the mechanical strength ones, meaning that concrete
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with high mechanical strength present, also, high values of modulusof elasticity.
Regarding the static modulus of elasticity, it could be observedthat concrete produced by earth of Milos present low values of static
Fig. 6. Dynamic modulus of elasticity versus static modulus of elasticity.
odulus of elasticity (Est.: 337–570 MPa) while the metakaolinoncrete exhibit much higher values (1950–5650 MPa).
Furthermore, by using hydrated lime in a higher proportion inoncrete the static modulus of elasticity is decreased. Synthesis 4xhibits value of static modulus of elasticity up to 4190 MPa whileyntheses 6 equals to 2419 MPa. Finally, concrete prepared by natu-al hydraulic lime or by mixing hydrated lime with a low percentagef metakaolin presents the lowest value of static modulus of elas-icity (Est. ∼824 MPa).
Regarding the dynamic modulus of elasticity, the maximumalue is reported for natural hydraulic lime concrete while highalues are reported for syntheses 3 and 7. On the contrary, the low-st values are reported for concrete of earth of Milos and concreteyntheses 9 (7539 MPa).
Comparing, the data of static modulus of elasticity with theynamic one, it could be observed that the data differ very much,hough, they present similar trend. The ratio of Ed/Est. varies inhe range 3–16, while these data seem to be close as the ultra-onic propagation velocity increases. Fig. 6 presents the correlationetween the static and dynamic modulus of elasticity.
. Conclusions
From the obtained results the following conclusive remarks cane point out:
the natural pozzolanic addition-earth of Milos presents low reac-tivity regarding the Ca(OH)2 consumption resulted to low valuesof final mechanical strength and mechanical strength acquisition;the artificial pozzolanic addition-metakaolin presents highreactivity regarding the Ca(OH)2 consumption due to its physico-chemical and mineralogical characteristics. Therefore, it could beused as a pozzolanic addition (in small percentages) in hydratedlime restoration mortars in order to ameliorate the early strengthof lime mortars;concrete prepared by mixing lime/metakaolin/ceramic frag-ment/sand:27.5/2.5/35/35 (p.w., %), present sufficient mechan-
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ical strength (Fc: 8.4 MPa, Ff: 1.50 MPa and Est.: 824 MPa), in12 months of curing time, assuring in that way the mechanicalcompatibility with the traditional structural materials of Byzan-tine structures;
[
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• concrete produced by natural hydraulic lime or lime/cement inmixing ratio (p.w.):1/1 or by mixing lime and metakaolin in ratio1/1 or 2/1 (p.w.) present too high values of mechanical strength,fact that could provoke a mechanical incompatibility problem inhistoric brickwork masonries;
• by increasing the hydrated lime percentage in the mixture andthe percentage of ceramic fragments in the total fraction of aggre-gates, a decrease in compressive and flexural strength, dynamicand static modulus of elasticity and apparent density occurs;
• the ratio of Ed/Est varies in the range 3–16, while these data seemto be close as the compressive strength increases.
Acknowledgements
To the “Thalis” Program “Seismo” who is supported financiallyby the Greek Ministry of Education and the European Union, whoexamines the earthquake protection of monuments in seismicareas.
References
[1] A.S. Cakmak, A. Moropoulou, C.A. Mullen, Interdisciplinary study of dynamicbehaviour and earthquake response of Hagia Sophia, Soil Dynamics and Earth-quake Engineering 14 (1995) 125–133.
[2] A. Moropoulou, A.S. Cakmak, G. Biscontin, Crushed brick lime mortars of Jus-tinian’s Hagia Sophia, in: J.R. Druzik, P.B. Vandiver (Eds.), Materials issues inart and archaeology V, Materials Research Society, New York, USA, 1996, pp.317–322.
[3] A.S. Cakmak, A. Moropoulou, M. Erdik, Interdisciplinary research proposal forthe earthquake protection of Hagia Sophia, 1995, submitted to Council ofEurope.
[4] A. Moropoulou, G. Biscontin, K. Bisbikou, A. Bakolas, P. Theoulakis, A. Theodor-aki, T. Tsiourva, Physico-chemical study of adhesion mechanisms amongbinding material and brick fragments in ‘Coccio pesto’, in: G. Biscontin (Ed.),Scienza e Beni Culturali IX, Bressanone, Italy, 1993, pp. 415–429.
[5] A. Bakolas, R. Bertoncello, G. Biscontin, A. Glisenti, A. Moropoulou, E. Tondello,E. Zendri, Chemico-physical interactions among the constituents of historicalwalls in Venice, in: J.R. Druzic, P.B. Vandiver (Eds.), Materials issues in art andarchaeology IV, Materials Research Society, New York, USA, 1995, pp. 771–777.
[6] A.S. Cakmak, M. Erdik, A. Moropoulou, A joint program for the protection ofthe Justinian Hagia Sophia, 4th International Symposium on the Conserva-tion of Monuments in the Mediterranean Basin, Conference Proccedings, in: A.Moropoulou, F. Zezza, E. Kollias, I. Papachristodoulou (Eds.), Technical Chamberof Greece, Rhodes, Vol. 4, 1997, pp. 153–171.
[7] A. Moropoulou, A. Theodoraki, K. Bisbikou, P. Michailidis, Restoration MortarsSynthesis of dushed brick imitating Byzantine lime and material technologies inCrete, in: J.R. Druzic, P.B. Vandiver (Eds.), Proc. of the Materials Research SocietySymposium, Materials Issues in Art and Archaeology IV, Materials ResearchSociety, New York, USA, 1995, pp. 759–769.
[8] A. Moropoulou, Reverse engineering to reveal traditional technologies: a properapproach for compatible restoration mortar, PACT, Journal of the EuropeanStudy group on Physical, Chemical Biological and Mathematical TechniquesApplied to Archaeology 58 (2000) 81–108.
[9] A. Moropoulou, A. Bakolas, P. Moundoulas, A.S. Cakmak, Compatible restorationmortars, preparation and evaluation for Hagia Sophia earthquake protection,PACT, Revue du Groupe Européen d’Études pour les Techniques Physiques,Chimiques, Biologiques et Mathématiques Appliquées à l’Archéologie 56 (1998)79–118.
10] A. Moropoulou, A. Bakolas, P. Moundoulas, A.S. Cakmak, Compatible restora-tion mortars for Hagia Sophia earthquake protection, in: G. Oliveto, C.A. Brebbia(Eds.), Advances in Earthquake Engineering 4, Earthquake Resistant Engineer-ing Structures, Publ. Wessex Institute of Technology, UK, 1999, pp. 521–531.
11] G. O’Hare, Lime mortars and renders: the relative merits of adding cement,The Smeaton Project, J.M. Tutonico, I. McCaig, C. Burns, J. Ashurst, AC1: FACE1
of compatible restoration mortars for the earthquake protection10.1016/j.culher.2013.01.008
Report, English Heritage, 1994.12] A. Moropoulou, A. Bakolas, A. Moundoulas, Thermal analysis in the evaluation
of compatible restoration mortars during setting and hardening, in: G.C. Papa-nicolaou, G. Parisakis (Eds.), Proc. Int. Conf. on 4th Mediterranean Conferenceon Calorimetry and Thermal Analysis, Patras, 1999, pp. 179–186.
