Nabi Yüzer

Hydraulic lime grouts are widely used for masonry consolidation, yet their environmental durability remains insufficiently understood. This study evaluated natural hydraulic lime (NHL) grouts incorporating Cappadocia Waste Earth (CWE) at CWE/NHL mass ratios of 0–0.50, while maintaining constant total binder mass and water-to-binder ratio, under freeze–thaw cycling, accelerated sodium sulphate exposure, and a comparative mortar-cup drying assessment. Newly generated mass-variation, ultrasonic pulse velocity (UPV), visual, and post-exposure scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS) data were interpreted together with previously published pre-exposure pore and moisture-transport characteristics. After 15 freeze–thaw cycles, all CWE-containing formulations showed significantly greater mass loss than REF, whereas CWE30, CWE40, and CWE50 did not differ significantly. UPV reduction correlated positively with mass loss (r = 0.781). Under accelerated sodium sulphate exposure, all CWE-containing formulations disintegrated by the twelfth cycle, although CWE30 deteriorated less severely than CWE40 and CWE50. Higher CWE/NHL ratios also produced more pronounced visible cracking during mortar-cup drying. SEM–EDS revealed Ca–Al–S-bearing needle-like products consistent with possible ettringite-like phases, without definitive phase identification. Overall, CWE30 showed the most favourable response among the CWE-containing formulations and is considered the most promising candidate for further conservation-oriented validation, but not an established optimum or recommended dosage.

1. Historic masonry structures constitute a significant component of the world’s cultural heritage, reflecting the social, architectural and technological characteristics of the societies that prod...

Masonry structures represent the architectural and cultural heritage of great historical importance. They have been used for public and residential buildings for several thousand years. Many well-preserved old masonry structures still exist, proving that this construction can overcome loads and environmental impact. These structures have been exposed to lateral and vertical loads and atmospheric influences throughout their lives. In masonry structures, undesirable damage, cracks, and voids may occur due to environmental factors or various natural disasters, such as earthquakes, which may cause the structure to collapse. Different conventional strengthening techniques are available depending on the purpose required for stone masonry walls. This study aims to evaluate the structural behavior of double-wythe travertine stone masonry walls strengthened by carbon fiber reinforced polymer (CFRP). For this purpose, two masonry stone walls, which are made of saw-cut travertine stones and constructed with English bond, a pattern formed by laying alternate courses of stretchers and headers, were constructed and tested under in-plane monotonic lateral load and constant axial load. Lateral load-displacement relations and failure mechanisms were discussed. In addition, triaxial compression tests of stone, mortar, grout, and stone-mortar composite materials were performed to determine constitutive relationships. Furthermore, three-dimensional (3D) nonlinear finite element analysis (NLFEA) of stone masonry walls using the Drucker-Prager (DP) yield criterion was performed for unstrengthened stone masonry walls and strengthened ones with grout injection and CFRP. The study findings revealed that the proposed numerical modeling approach can accurately predict the experimental lateral load-displacement behavior of both strengthened and unstrengthened specimens subjected to in-plane combined axial loading and shear. Additionally, the model demonstrated its capability to simulate the experimental load-displacement and cracking patterns effectively.

This research aims to study the bacterial healing process of cement mortar samples exposed to durability effects using bacteria characterized by their ability to precipitate calcium carbonate. Sporosarcina pasteurii is widely used for bacterial healing. This research investigates the performance of S. pasteurii with five types of bacteria isolated from caves (Viridibacillus arenosi, Streptomyces spororaveus, Bacillus zhangzhouensis, Stenotrophomonas rhizophila, and Serratia quinivorans). Cement mortar samples were exposed to high temperatures and freeze–thaw effects to create microcracks. Microcracks were also induced by applying flexural strength loads. Then, the formed microcracks were healed using spraying and injection of the bacterial solution for the first group for 90 days. The control and healed samples were assessed using flexural and compressive strength, water absorption, capillary water absorption, and ultrasonic pulse velocity (UPV) tests. Microstructural analysis was also conducted to evaluate the bacterial healing products. Subsequently, statistical analysis was performed using the results of these tests to compare the various bacterial efficiencies. As a result of the statistical analysis, the total efficiency scores obtained in the statistical analysis were 119 for Stenotrophomonas rhizophila, 112 for Viridibacillus arenosi, and 105 for S. pasteurii. Thus, Stenotrophomonas rhizophila and Viridibacillus arenosi showed the best healing performance compared to the other types of bacteria.

Cappadocia Region (World Heritage Site registered by UNESCO) carries thousands of rock-cut structures, masonries and fairy chimneys, which have been used in every aspect of daily life. Damages occurred during their working life, and restoration with inappropriate materials are threatened these structures. Moreover, an enormous amount of waste material is excavated throughout the carving process, passing approximately 10 million cubic meters per annum, creating pollution in the region, and not being used efficiently. This study aims to use Cappadocia waste earth (CWE) in the grout for consolidation and strengthening rock-cut structures, masonries and fairy chimneys located in Cappadocia region. The utilization of this waste earth in the grout prevents the destruction of these valuable structures and provides a solution to a critical environmental problem. The experiments were conducted employing by 30%, 40%, and 50 wt% of Cappadocia waste earth with natural hydraulic lime in the existence of chemical admixtures. The influence of ambient temperatures (5°C, 20°C, and 40°C) and time-dependent behavior on the rheological performance of grouts were investigated. The findings revealed that dosages of Cappadocia waste earth, different environmental temperatures, and constant shearing (time-dependent) have critical roles in determining the optimum requirements for injection. GHRAPHICAL ABSTRACT