Opal-A rich additives used in ancient lime mortars

Ancient stone and brick masonry mortars from three monuments in Konya, Central Anatolia dated to the Anatolian Selçuk Period (12th and 13th centuries AD) were examined for their raw material composition and durability characteristics to understand some characteristics of medieval mortar technology. Optical microscopy, XRD, SEM, EDX, FTIR and TGA analyses revealed that the mortars contained high percentage of lime binder totally carbonated into micritic calcite. Coarse and medium aggregates were mainly composed of sandstone and metamorphic rock fragments, quartz, feldspar and mica minerals. Opal-A was found in considerable amounts in the fine aggregates, likely not derived from the coarser ones but added separately. Pozzolanic activity of the fine aggregates was determined by conductometric measurements. Their ability to form C-S-H was observed by treating them with saturated Ca(OH)2 solution. Bulk density and total porosity measurements showed that the mortars were highly porous due to the use of high amount of lime. On the other hand, they possessed sufficient mechanical strength. Mechanical properties were determined by point load tests and ultrasonic pulse velocity measurements. They were expressed as uniaxial compressive strength (UCS) and modulus of elasticity (Emod) in MPa. The results were also discussed in terms of durability characteristics of the mortars. They were expressed with the use of uniaxial compressive strengths in dry and wet states, and total porosity values. The mortars were considered to have high durability to wetting and drying cycles but had poor durability to the crystallization of water-soluble salts

Antique stone quarries in Turkey: a case study on tuffs in the Temple of Apollon Smintheus

All types of stones have been used as building stones, depending on their durability, visual harmony with the intended construction and availability. In the Hellenistic period, as in other periods, tuff was preferred as a building stone due to its convenience – it was easy to extract, transport and use for building. In the present study, three ancient quarries that were the possible tuff sources for the Apollon Smintheus Temple in C¸ anakkale are investigated by comparing the durability properties of stones in the temple and in the quarries. These properties are determined using physical and physico-mechanical tests, comparing fresh and artificially weathered samples. Microstructural and elemental correlations were found using optical microscopy, stereomicroscopy, X-ray diffraction, scanning electron microscopy, methylene blue adsorption and X-ray fluorescence analyses. The results indicate that temple tuffs and two of three quarries have similar geological engineering and microstructural properties with the strong claim that those two quarries could have been the source of building stone for the temple.Peer reviewe

Tarihi mermerlerin korunmasında biyomineralleştirme ve nanotaneler teknolojilerini kullanarak yeni metotlar geliştirme

TÜBİTAK MAG Proje01.01.2007Anıtların ve arkeolojik alanların atmosferik koşullara açık olan taşları, çeşitli fiziksel, kimyasal ve biyolojik değişimlere uğramaktadırlar. Zaman içinde bu değişimler, taşın mikroyapısında yüzeyden içeriye doğru ilerleyen bozulmalara neden olmakta ve oluşan önemli değişiklikler, toplam gözenekliliğin artması, mekanik özelliklerin azalması, kimyasal bileşim değişimleri ve diğerleri olarak izlenmektedir. Tarihi taşlardaki bozulma değişimleri, görsel olarak da izlenmektedir. Bunlar, renk değişimleri, birikimler, pul ve kabuk oluşumu şeklinde ayrılmalar ve kayıplar, çatlaklar, toz, taneler, ve/veya parça şeklinde kopmalar gibi malzeme kayıpları olabilir. Korumanın uzun dönemde başarısını sağlamak için,tarihi taşların koruma müdahaleleri görmüş kısımlarının özgün taşla fiziksel, mekanik ve kimyasal uyumunun sağlanmasına çalışılmaktadır. Zayıflamış taşı sağlamlaştırma çalışmalarında uyumluluk, en iyi şekliyle, taşa benzer yapıyı tekrar oluşturarak sağlanabilir. Bu çalışmanın amacı, bozulmuş arkeolojik mermerleri nano taneli çözeltilerle benzer mikro yapı oluşturarak sağlamlaştırma yöntemleri geliştirmektir. Sağlamlaştırma işlemleri, çeşitli nano taneli kalsiyum hidroksit çözeltileri, çeşitli kolloidal silika çözeltileri kullanılarak ve biyomineralleştirme deneyleri ile çalışılmıştır. Sağlamlaştırma işlemi görmüş örnekler, kalın kesitlerin SEM-EDX analizleri, ince kesitlerin optik mikroskopanlizleri, ve toz örneklerin XRD ve FTIR analizleri ile incelenmiştir. Analiz sonuçları işlem görmemiş örneklerle karşılaştırılmıştır. Sonuçların başarılı olduğu görülmüştür. Bunlara ek olarak sağlamlaştırmanın uyumluluğunun ve dayanıklılığının uzun zaman için değerlendirilmesinde dilatasyon özelliklerinin taşıdığı önem, örneklerin ısıl ve bağıl nem değişmeleri sırasındaki dilatasyon özellikleri takip edilerek tartışılmıştır.An exposed stone either in an archaeological site or on a monument is subject to weathering by physical, chemical and biological processes. In time, those weathering processes cause considerable changes in microstructure of stone, such as increase in porosity, decrease in mechanical properties, quite a number of changes in chemical composition etc. starting from exterior surfaces towards interiors of the stone. Those changes are also visible by change in color, detachments as scales and flakes, crack formation, material loss as powdering, granular disintegration, outbursts etc. Physical, mechanical and chemical compatibility with the original stone is a requirement for the conservation treatments of historic stones. During the consolidation treatments of the weak stone, compatibility can best be achieved by producing a similar structure to the original stone. The aim of this study is to develop procedures for the consolidation of deteriorated marbles by forming similar microstructure network in them. Consolidation treatments with nanodispersive calcium hydroxide solutions, colloidal silica solutions and biomineralization have been studied. The treated samples were examined by SEMEDX analyses of cross sections, by the analyses of thin sections with optical microscopy and by the analyses of powdered samples with XRD and FTIR. The results were compared with the untreated marble samples. The treatments were found to be successful. Compatibility and durability assessment of the consolidation treatments were further discussed including the results of the preliminary studies on the kinetic follow up of the hygric and thermal dilatation properties

Atmospheric Weathering of Historic Monuments and Their Related Conservation Issues

Atmospheric environment affects the materials of historic monuments and their structure starting from the time of their construction. Daily and seasonal changes in temperature and humidity, wind, snow and rainfall, soluble salts carried by water, biological agents, pollutant gases and particulate matter are some of the agents in atmospheric environment that introduce weathering by physical, chemical and biological processes in the materials of the monuments such as natural building stones, bricks, mortars and plasters, mud brick etc. The weathering processes need to be well diagnosed by identification of main mechanisms of decay and major responsible agents, degree and depth of deterioration expressed with measurable parameters of physical, physicomechanical properties, and micro structural changes together with their distribution on the monument. Success of conservation treatments strongly depend on those diagnostic studies and compatibility of the treatments with the deteriorated and relatively sound parts of the historic materials. Current approach to materials conservation is to be able to make minimum intervention to historic material by targeting the conservation treatment to the deteriorated area for the purpose of controlling the deterioration factors and achieving compatible and durable conservation of historical material. In this presentation, two examples of diagnostic research and conservation treatments based on and guided by the diagnostic results are summarized concerning historic stone monuments exposed to atmospheric environment since more than two thousand years. The first example is on the marble walls of Temple of Augustus in Ankara exposed to polluted urban atmosphere. The second example is on the limestone statues of Nemrut Mount Monument in Adıyaman-Turkey, exposed to rural atmosphere with harsh climatic conditions. Finally, a brief discussion on current research issues related to historic materials conservation in atmospheric environment is made

Preparation of pozzolanic lime mortars for repairing limestone of Nemrut Dag Monument

The aim of this study is to prepare pozzolanic lime mortars to be used for stone repairs such as sticking large detached scales, filling gaps and large cracks in the deteriorated limestone objects of Nemrut Dağ Monument in Adıyaman Turkey. Mortar samples from rubble stone masonry of Kahta Castle, a medieval structure, in close vicinity of the Nemrut Dağ Monument, were investigated to set an example for the preparation of repair mortars. Repair mortar mixtures were prepared by using laboratory grade Ca(OH)2, local river sand and two types of pozzolans; metakaolin and natural trass. Basic physico-mechanical properties of historic mortars and repair mortar cubes after 60 day curing period were determined. Both historic and repair mortars were investigated by optical microscopy and SEM-EDX, XRD, FTIR. Pozzolanic activity of the pozzolans used in this study, fine aggregates of historic mortars and fine aggregates of local river sand were investigated. CSAH and CSH were detected by XRD and SEM-EDX in the repair mortars prepared with added metakolin. After 60 days, the bulk density and effective porosity values of prepared repair mortar cubes were observed to be slightly lower than that of historic mortars. The compressive strength of prepared mortars with added metakaolin were quite near to the compressive strength historic mortars, however their carbonation were not yet completed. The results were further evaluated in comparison with historic mortars and for the preparation of compatible and durable repair mortars

Effect of some surfactants on SO2-marble reaction

In the polluted atmosphere, sulphur dioxide (SO2) reacts with calcite (CaCO3) in marble producing calcium sulphite hemihydrate (CaSO3·0.5 H2O) and gypsum (CaSO4·2H2O). Gypsum develops crust at rain-sheltered surfaces and then, being more soluble, accelerates erosion at areas exposed to rain. Eventually, all these lead to significant deformations in the appearance and structure of marble surfaces. Clearly, some precautions must be taken to stop or at least to slow down this deterioration process which destroys our cultural heritage. In this study, we have investigated the possibilities of preventing the SO2-marble reaction by using water-soluble surfactants: Abil Quat 3270 and Tween 20. Experiments for measuring their effects have been carried out at conditions simulating the dry deposition of SO2. Infrared spectrometry and scanning electron microscopy were used to analyze the mineralogical composition and morphology of the reaction products. The extent of sulphation reaction was calculated by determining calcium sulphite hemihydrate and gypsum quantitatively by an IR approach and also by weight increases observed during the progress of SO2-marble reaction. A 10% decrease is observed in the total sulphation with both surfactant applications. The results have been discussed in relation to the possible stages of sulphation reaction and surface reactions of calcite