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SUMMARYThis paper presents the effect of elevated temperatures up to 700°C on compressive strength and water absorption of two alkali-activated aluminosilicate composites (one of them is river sand aggregate geopolymer concrete; the other one is crushed sand aggregate geopolymer concrete) and ordinary Portland cement based concretes. To obtain binding geopolymer material, Elazığ ferrochrome slag was ground as fine as cement, and then it was alkali activated with chemical (NaOH and Na 2 SiO 3 ). Geopolymer concrete samples were produced by mixing this binding geopolymer material with aggregates. At each target temperature, concrete samples were exposed to fire for the duration of 1 h. Fire resistance and water absorption of geopolymer and ordinary Portland cement concrete samples were determined experimentally. Experimental results indicated that compressive strength of geopolymer concrete samples increased at 100°C and 300°C temperatures when compared with unexposed samples. In geopolymer concrete samples, the highest compressive strength was obtained from river aggregates ones at 300°C with 37.06 MPa. Water absorption of geopolymer concrete samples increased at 700°C temperature when compared with unexposed samples. However, a slight decrease in water absorption of concrete samples was observed up to 300°C when compared with unexposed samples. SEM and X-ray diffraction tests were also carried out to investigate microstructure and mineralogical changes during thermal exposure.

Heritage masonry constructions constitute an important percentage of the structures in many countries. These structures are highly vulnerable to environmental changes (such as earthquakes), and significant losses in masonry historical constructions occur even in a moderate earthquake. For this reason, damage assessment studies of these structures before earthquakes are of great importance. After an earthquake, historical buildings in Turkey were examined and it was found that many buildings underwent damage. In these structures, damage occurs during the earthquake due to the use of low‐quality materials and a lack of sufficient connections between the layers. In these buildings, damage especially occurs in the parts that undergo restoration. Since low‐strength repair mortars are generally used in the restored sections, wide cracks have occurred in the building elements under the effect of earthquakes. This study aimed to produce alternative materials that could be used as geopolymer binders in restorated buildings. The mechanical, physical, and microstructural characteristics of the geopolymer samples were investigated in detail using laboratory tests. As a result, the strength of geopolymer repair materials with 8 M and 5% calcium hydroxide (Ca[OH]2) was very high when compared with other values. High‐strength compatible alternative geopolymer repair mortars that could be used for restoration were produced. For this reason, mortar is considered a significant application for repairing and strengthening buildings.

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Old stone buildings constitute a significant percentage of the residential buildings in many countries. These structures are highly vulnerable, and important losses in masonry structures occur even in moderate earthquakes. Therefore, safety evaluations of these structures have gained significant attention in recent years. In this study, the mechanical, physical and microstructural characteristics of tuff samples used in the old buildings were investigated in Battalgazi within the boundaries of Malatya Province during the Seljuk time. The characteristics of the building materials were examined in detail using in-situ and laboratory tests. Because adequate samples could not be obtained from the historical buildings, quarry areas with the same characteristics were identified. First, original building stone (OBS) used in construction was taken from fallen and unusable blocks. Then, the properties of the restoration building stones (RBS) brought from the quarries were investigated. The RBS samples were also examined using in the laboratory, and the mechanical and microstructural properties of the building components were determined. The dynamic and static moduli of elasticity were determined using ultrasonic pulse velocity and uniaxial compression test. The OBS and RBS samples yielded similar results after the microstructural analyses. Our results showed that the dynamic elastic modulus value was higher than the static elastic modulus value. The results revealed by both methods showed that the static and dynamic elastic moduli were closely linked. The OBS and RBS samples exhibited microlitic porphyritic and vesicular textures and nearly the same mineralogical and textural characteristics.

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Historical masonry structures that connecting the past to the present have great importance because they represent the experiences and characteristics of various cultures. Therefore, the protection of historical structures is important. In this study, the structural response of the historical masonry Mosque was evaluated through dynamic analyses. For this purpose, the Sütlü Minaret Mosque which is located in Malatya, Turkey, was investigated. The three-dimensional model of the historical mosque was generated with ANSYS software. The material properties of the mosque were obtained with experimental tests. The time history analyses were used to obtain the seismic behavior of masonry mosque. In the time history analyses, six different strong ground motion records, including the 2020 Elazığ earthquake, were used. After the analysis, displacement and stress values in the mosque were given. The absolute peak displacement value among these earthquake records was obtained from the 1999 Düzce earthquake and the highest principal compressive and tensile stress values were determined for the 2010 Darfield earthquake. Also, the crack regions which occurred in the mosque after the 2020 Elazığ earthquake were compared with the dynamic analysis result of the 2020 Elazığ earthquake. The crack regions formed after the Elazığ earthquake are similar to the possible crack regions formed after the dynamic analysis.