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Structural restoration of heritage masonry buildings is a serious challenge. Meeting the requirements of current building codes is not sufficient to preserve the historic character of heritage buildings. The selected technique must be consistent with aesthetics, function, and the requirements of strength, ductility, and stiffness. This paper provid...
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... new walls are self-bearing, even if they are structurally connected to existing masonry walls. Reinforced concrete overlays may be built only on the interior of the existing walls of heritage masonry as shown in Figure 3. Adequate aggregate size and additives are used to prevent creep and improve adhesion to masonry. ...
Citations
... To carry out restoration works on monuments, certain standards and procedures must be followed. These standards are defined by regulations such as The Venice Charter (1964) and ICOMOS (2003) (Korany 2011). Regarding the masonry line-segment Bembo-Saint Francis the following are proposed. ...
This paper focuses on the line-segment Bembo-Saint Francis of the masonry walls of Chandakas in the city of Heraklion, Greece. The construction of the wall was decided in 1462, but 100 years were needed until the design was finalized and construction began at the beginning of the 16th century. The line-segment was constructed as part of the fortification system but, from a geotechnical point of view, acts as a gravity retaining wall, due to the existence of backfilling material. It suffered severe damages during the long siege by the Ottomans (1648-1669). Furthermore, activities and loads implied and applied by the modern operation of the city caused it to deform and swell. A numerical investigation is performed using the Finite Element code Plaxis to analyze the stability of the wall-ground system. Emphasis is given on the ways of calculating the modulus of elasticity of the wall. Parametric analyses are performed and the results indicate that neither the methods used to calculate the modulus of elasticity of the wall nor the materials of which the wall is built affect the overall stability. Finally, various methods of restoration and support are recommended, significantly increasing the safety factor.
... Przywrócenie do stanu pierwotnego jest ostatecznym celem napraw i renowacji (8). W celu przywrócenia stanu pierwotnego należy ograniczyć te działania do minimum (9). Przywracanie do stanu pierwotnego oznacza odtworzenie starej konstrukcji poprzez usunięcie dodatkowych warstw lub ponowne jej odtworzenie z istniejących elementów, bez wprowadzania nowych materiałów. ...
... The objective of restoration should be with minimum intervention. (9). Restoration means bringing back the original condition of the structure by removal of any additional layers or by reassembling the same with existing components without introducing any new materials. ...
Streszczenie Renowacja i konserwacja obiektów dziedzictwa kulturowego w każdym kraju jest zadaniem trudnym i czasami wymaga dużej uwagi. Jest to równocześnie ważne dla podtrzymania kultury i dzie-dzictwa społeczeństw. Jednak często bardzo trudno jest znaleźć odpowiednie materiały stosowane w przeszłości i dlatego w wyniku zastępowania ich dostępnymi spoiwami cementowymi, może dojść do uszkodzenia starych materiałów. Z tego powodu trzeba zbadać te antyczne materiały i opracować podobne zastępcze, o zbliżonych właściwościach. Ten materiał zastępczy powinien mieć podobny skład mineralny i właściwości fi zyczne, a wówczas nie będzie stwarzał problemów w trakcie naprawy i po jej wykonaniu. W niniejszej pracy, przy użyciu nowoczesnych technik analitycz-nych, a przede wszystkim mikroskopii elektronowej, rentgenografi i i spektroskopii w podczerwieni, zbadano skład antycznej cegły pływającej, stosowanej w indyjskim obiekcie zabytkowym. Okre-ślono również właściwości fi zyczne, a mianowicie ciężar właściwy, gęstość nasypową, zawartość pustek i porowatość. Na podstawie przeprowadzonej analizy można stwierdzić, że cegły były lekkie, o czym decydowała duża porowatość, i mogły pływać w wodzie, gdyż były to pojedyncze pory zamknięte. Cegły wykonano z gliny prażonej w niskich temperaturach, co pozwoliło uzyskać dużą porowatość. Skład chemiczny cegieł, oznaczony pod mikroskopem elektronowym przy zastosowaniu mikroanalizy rentgenowskiej, składał się z kwarcu, tlenku glinu i hematytu. To niskotempera-turowe prażenie gliny zostało poparte analizą FTIR, wykazującą wiązania Si-O, które nie są trwałe w wysokiej temperaturze. Słowa kluczowe: obiekty dziedzictwa kulturowego, lekka cegła, inżynieria odwrotna Summary Restoration and preservation of Heritage Structures in any country is a challenging task and sometimes requires urgent attention. Moreover , it is important for sustenance of culture and heritage of the society. But many times, it is very diffi cult to fi nd matching materials used in the past and hence due to use of available cementitious materials there can be degeneration of existing material. In view of this, there is a need to characterize these ancient materials and develop alternate materials with almost similar characteristics. With this knowledge, an alternate material similar in mineral composition and physical properties need to be developed, which will not have compatibility issues during and after repair. In the present study, the material characterization of an ancient fl oating brick at an Indian Heritage site was examined using modern analytical techniques like SEM-EDS, XRD and FTIR. In addition, the physical properties like specifi c gravity, bulk density, voids ratio and porosity were also determined. From the analysis, it could be confi rmed that the bricks were light in weight due to the pores content and could fl oat in water due to the non-interconnected porosity. Also, the presence of quartz, alumina and hematite from SEM-EDS analysis confi rmed that these bricks were made of fi ring the clay, at lower temperatures, to induce pores. This low temperature fi ring of clay was supported by FTIR analysis indicating the presence of Si-O bond that would have disappeared at higher temperature.
... The evaluation of existing reinforced concrete structures has become a necessary and important process for engineers on a large scale due to the aging of existing structures and buildings, as reinforced concrete has become a global construction material during the past decades to this day (Korany, 2011). There are a large number of existing facilities that need either rehabilitation or removal as a result of natural or man-made factors and causes such as, natural disasters, earthquakes, wars, conflicts, and other sudden causes that lead to various degrees of damage. ...
... The new mortar is put in layers and tooled when it is become hardly thumb printed. The new mortar should be similar as much as possible with the current disintegrated mortar in properties, texture and color (Korany, 2011). Repointing is required if: mortar is profoundly disintegrated (in excess of 13 mm) or has dropped out, hairline splits or bigger have shaped in the mortar, the concrete structure and mortar do not stick to, bringing about a break or a hole between the two, or the mortar is setting freely in the joint (Korany, 2011). ...
... The new mortar should be similar as much as possible with the current disintegrated mortar in properties, texture and color (Korany, 2011). Repointing is required if: mortar is profoundly disintegrated (in excess of 13 mm) or has dropped out, hairline splits or bigger have shaped in the mortar, the concrete structure and mortar do not stick to, bringing about a break or a hole between the two, or the mortar is setting freely in the joint (Korany, 2011). ...
Civil engineering not only deals with the construction of various structures but also works for their maintenance and rehabilitation. The current era requires efficient and sustainable methods for any job and given that concrete is a material that is heavily relied upon at the present time in construction, therefore its sustainability through the rehabilitation and restoration of buildings is a must and very important. There are many techniques that can be followed in the rehabilitation and restoration of damaged concrete sections, i.e. exposed to cracks, corrosion or disintegration, as each process has its advantages and limitations, which requires the engineer to know the type of damage, the main cause of it and the best way to repair it. Therefore, this paper uses the descriptive methodology to review the latest rehabilitation and restoration techniques used in the treatment of concrete structure including, repointing, grouting, reinforced injection, polymeric materials permitted by fibers and reinforcement of concrete structures, overlays, jacketing, base isolation and stitching. The researcher concluded that these techniques are effective, but each has its determinants of use that must be taken into account before applying them.
... Restoration is the ultimate aim of Repair and Rehabilitation [9]. The restoration should be done with minimum intervention to the heritage structures [10]. Restoration means, bringing back the original condition of the structure by removal of any additional layers or by reassembling the same with existing components without introducing any new materials. ...
The paper discusses about the characterization of ancient mortar of an 800 year old heritage site in Southern India. The repair of heritage structures is largely neglected and even if attended, incompatible materials were used in the previous repairs. Hence, characterization of ancient mortar of heritage structure is an essential step before preparation of repair mortar. In the current study, characterization using acid-dissolution test, SEM-EDS, XRD, FTIR and TGA-DTA were conducted. Acid-dissolution analysis of ancient mortar confirmed the binder to aggregate ratios in the range of 1:5 to 1:7, while, analytical techniques viz; SEM-EDS and XRD confirmed presence of calcite and quartz crystals. The elemental and mineral composition of these mortars were analyzed using EDS and XRD respectively. The results were further reinforced with thermo-gravimetric analysis, in which, calcite decomposition was observed at around 700–800 °C. Also, organic content in the form of carbohydrates was detected based on FTIR analysis on heritage mortars.
Cultural heritage is a characteristic feature of every country that tells about the past. A country seeking to preserve its history must respect, protect and restore cultural heritage objects: buildings, monuments, historical places and all things that are historically valuable. When it comes to buildings as cultural heritage objects, a problem is usually relevant: how to restore them without losing their authenticity. In order for valuable building structures not to lose value during their restoration, materiality, condition and rehabilitation technique are determined before work is carried out. This article deals with the problems of the reconstruction of brick structures of cultural heritage buildings. The authors analyze the technologies for strengthening and restoring brick walls. A decision support system (DSS) for evaluating alternative reconstruction technologies for damaged building structures is being established. The indicators for multi-criteria assessment of reconstruction technologies are determined, their importance calculated and the multi-criteria TOPSIS method selected and described. Damages to brick walls in a particular building are described and three alternative technologies are determined for their restoration. The assessment by the decision-support system shows that in a particular case the most rational technology is the “bricking up of missing wall fragments”. Developed DSS is a unique and useful tool that can be used by professionals selecting rehabilitation techniques for vulnerable building structures.
Cracks are one of the most common expressions of damage in masonry structures. Aside from aesthetic issues, they can compromise the overall behaviour of the structure; therefore, they are undesirable and need to be repaired. The repointing technique is traditionally implemented in this context, especially in historical masonry. Nevertheless, future damage is not prevented and may arise again, thus requiring renewed repointing interventions.The paper describes a preliminary study conducted at Delft University of Technology to investigate the applicability of the innovative self-healing technology to enable an automatic repair of masonry cracks. A bacteria-based self-healing mortar, developed to repair existing concrete structures, was implemented to explore the capacity of couplets to recover their original strength and aesthetic aspect after multiple damaging events. Specimens built with calcium-silicate and clay bricks were subjected to subsequent cracking cycles using a crack-mouth-opening-displacement controlled bond-wrench test.Experimental results showed that self-repair, in terms of strength restoration and aesthetic filling of cracks, occurs even after multiple cracking cycles when the self-healing mortar is used with both types of bricks, optimizing the autogenous healing of cement-based mortars. In this context, the healing effectiveness tended to decrease as the crack width and the number of cycles increased. The effectiveness varied also according to the types of brick and healing environment used, e.g. under humid conditions (RH ~ 95%), 50% vs 80% of the original capacity was regained in fully separated couplets made respectively with clay and calcium-silicate bricks. This outcome provides the ground to delineate the remaining testing campaign.KeywordsMasonryHeritageRepairCracksSelf-healing
13 Heritage structures are susceptible to deterioration as they age naturally and are exposed to 14 severe environmental conditions. One way to prolong the lifespan of these structures and reduce 15 the rate of deterioration is through the application of consolidative treatments. This treatment 16 acts by penetrating the permeable surface of the substrate and attempt to increase cohesion 17 among the grains and reduce the impact of adverse environmental conditions. However, ensuring 18 compatibility between the consolidant and the substrate is complex, which depends on the 19 substrates' material characteristic and its exposure conditions. If the wrong consolidant is 20 chosen, it can accelerate deterioration instead of restoring the structure. This study aims to 21 evaluate the effectiveness and compatibility of two types of commonly used consolidants, 22 namely acrylic-polymer and silane-based consolidants, on samples of stone and fired clay bricks 23 of varying qualities and characteristics commonly found in heritage masonry structures. The 24 performance of the consolidants is assessed by comparing the initial physical, mechanical and 25 microstructural properties of the substrate samples obtained through various testing methods, 26 with the properties of treated and untreated samples after being subjected to accelerated 27 weathering in order to analyze the weathering resistance. After which, a secondary comparison is 28 made by treating the weathered untreated samples in order to assess the extent of restoration that 29 happened when the consolidants are applied to the damaged samples. The results obtained from 30 this study will guide decision makers who wish to use silane or polymer based consolidative 31 treatments on heritage structures so that they can understand what kind of results to expect with 32 J o u r n a l P r e-p r o o f 2 respect to the substrate and the properties it possesses. From this they can make informed 1 decisions to choose the treatment best for them in order to address their respective needs. 2
Material science is one of the interesting areas of specialization in research and development in all fields of engineering, especially all major civil engineering developments can be related to advancement in materials. This also has a significant influence on our ecosystem. In the present study, the principles of green engineering have been demonstrated using the example of heritage buildings that have survived more than 500–700 years with minimal damage. Even though depreciation of material takes place over a period of time, there is a gulf of difference between materials used in present construction and the past mortars and binders used in ancient construction. Most of the heritage monuments require retrofitting, and there is a need to observe the concept and interphase keenly. Present work focuses on the study of heritage materials as microanalysis to get a precise inference about the mortars and binders used in these structures centuries ago. As part of this case study, one sample has been extracted from the ancient structures and were analysed for chemical analysis by Energy dispersive X-ray spectrometry (EDS) to find-out the exact mix proportion of elements in specific volume. Magnesium, silica, and calcium were found to be higher in the samples.
In the contemporary research work, the Response Surface Methodology (RSM) is used to simultaneously maximize compressive strength and minimize the absorption of water in the cement mortar (nano materials blended). Three important process parameters including nano silica (0–3wt%), w/c ratio (0.48–0.52wt%), and Plasticizers (0–1wt%) were augmented to acquire the best values of response using the numerical box-behnken design with desirability analysis. The nano silica was replaced by cement in 0%, 1%, 2%, and 3% and water–cement ratios of 0.48, 0.50, and 0.52 with the addition of 1% of polycarboxylate admixture in the cement mortar separately. The research work aims to increase the mechanical properties of cement mortar using nano silica and mineral admixtures. The compression test was carried out using ASTM standard mortar cube to investigate their mechanical properties. The optimal results showed that the nano mortar with 2% nano silica, 0.5 water cement ratio (w/c), and 1% plasticizers, attaining high compressive strength and effectively increasing the mechanical properties of cement mortar.
Wire arc additive manufacturing (WAAM) is one of the metal additive manufacturing methods in which rapid fabrication is possible for components of big size. A significant amount of heat energy is transferred to the workpiece during this process, with a defined idle period so that the workpiece cools down between each layer of deposition. This variable cooling rate technique keeps the workpiece from collapsing and crack growth by maintaining a proper inter-pass temperature. The main challenge is to choose an inter-pass ambient cooling time to mitigate the residual stresses and distortions induced in the workpiece. A numerical model is developed to study the variation of residual stress with respect to change in the cooling time of WAAM process. The material’s thermal and mechanical behaviour was instigated using finite element analysis, by introducing DFLUX SUBROUTINE within ABAQUS 6.20 SOFTWARE. The simulation results were analyzed and the optimum inter-pass cooling time obtained was 800 sec.
