Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2026The effect of mine waste ratio and curing duration on the mechanical properties of ground granulated blast furnace slag-based geopolymer mortars
Aksüt, Yavuz Selim; Nas, Evin; Sünnetçi, Kadir; Kaya, Yusuf
This study investigates the mechanical and microstructural behavior of ground granulated blast furnace slag (GGBFS)-based geopolymer mortars in which mining waste (MW) was used as a partial binder replacement (0–30%) under ambient water curing for 7–90 days. Increasing MW content reduced workability and slightly prolonged setting due to its coarser and less reactive characteristics. Mechanical performance improved with curing time and mixtures with moderate MW levels achieved the best strength and microstructural densification. Water absorption and porosity decreased with age, reflecting progressive gel formation. Scanning electron microscope–X-ray diffraction (SEM-XRD) analyses verified matrix densification and enhanced gel development at intermediate MW ratios. Overall, the findings show that controlled MW incorporation can optimize the balance between strength, pore structure and sustainability, enabling ambient cured GGBFS-based geopolymers without thermal curing. The study provides new insights by using MW as a binder phase replacement while preserving precursor chemistry, a rarely explored approach.
- MakaleYalnız künye2026Analysis of microstructural properties and durability characteristics of geopolymer mortars with mining waste
Aksüt, Yavuz Selim; Kaya, Yusuf; Sünnetçi, Kadir
The growing environmental concerns over resource depletion and carbon emissions from cement production have accelerated the search for sustainable alternatives to conventional concrete. In this context, geopolymers have emerged as promising binders, particularly through the utilization of aluminosilicate-rich industrial wastes to reduce environmental impact and support waste recycling. This study examines the mechanical and durability properties of geopolymer mortars produced by partially replacing ground granulated blast furnace slag (GGBFS) with mining waste (MW) at ratios of 0%, 10%, 20%, and 30%. The mixtures were activated using 10 M sodium hydroxide and sodium silicate under standard water curing conditions. Mechanical strength, ultrasonic pulse velocity (UPV), freeze–thaw resistance, and sulfate durability were evaluated. The optimum performance was obtained with 20% MW, which achieved a 30.4% increase in flexural strength and 18% in compressive strength at 7 days. This mixture also showed the lowest mass (10.69%) and strength loss (18.36%) after 50 freeze–thaw cycles. Scanning electron microscopy analysis confirmed enhanced gel formation and microstructural densification. The findings demonstrate that controlled use of MW not only improves durability but also promotes sustainable binder development in geopolymer technology.
- MakaleAçık Erişim2026Detrital zircon ages, Lu-Hf isotopes of zircon grains, Sr-Nd isotopes on whole rock and geochemistry of Campanian turbidites in the Eastern Pontides (NE Türkiye): A provenance assessment and Gondwana records
Eker, Çiğdem Saydam; Yücel, Cem; Kaygusuz, Abdullah; Aydınçakır, Emre; Jeong, Youn-Joong; Yılmazer, Sinan; Sünnetçi, Kadir
Detrital zircons are crucial stand-ins for the history of continental crust growth and disintegration, as well as the dispersal and assembly of supercontinents. Detrital zircons are effectively used to assess crustal history because sediments transport zircons from source rocks that are no longer at the surface. This study presents detailed Lu-Hf isotopic, U-Pb geochronological analyses of zircon, Sr-Nd isotopic analyses and whole-rock geochemical results from sandstone, volcanically derived sandstone and tuff samples of the Campanian-aged Bozbent Member in the Eastern Pontide Orogen belt of the Sakarya Zone. Sedimentological analyses show that the Bozbent Member was transported and deposited by turbidite currents, while petrographic and geochemical analyses show that the sandstones range from greywacke to litharenite. In this study, U-Pb ages of detrital zircon obtained from Campanian sandstones are presented, along with in situ εHf data. A magmatic origin is indicated by the majority of zircons' oscillatory zoning and by Th/U ratios ranging from 0.2 to 1.5. The ages of detrital zircons range from 2819 to 78 Ma, with most of these zircons being Proterozoic (552–994 Ma). Proterozoic zircons are detrital zircons associated with the Gondwana and the African Craton. The whole-rock geochemical data and Sr-Nd isotope compositions of the sandstones are consistent with local Carboniferous felsic plutons, Jurassic mafic and felsic plutons, Jurassic volcanic rocks, Jurassic clastic rocks and clastic material from Precambrian recycled sediments. It was calculated that more than 90% of the detrital zircons had crystallisation ages older than their depositional ages (CA-DA > 150 Ma, indicative of an extensional basin model). These findings indicate that the Campanian-aged Bozbent Member turbiditic sequence in the Eastern Pontides was deposited in an extensional fore-arc basin and therefore exhibits the petrographic and geochemical characteristics of passive margin sandstones.
- MakaleYalnız künye2019Jurassic acidic magmatism in a back-arc setting, eastern Sakarya Zone, Turkey: Geochemical constraints and an evolutionary model
Dokuz, Abdurrahman; Sünnetçi, Kadir
The Early Jurassic in the Sakarya Zone, Turkey, was dominated by basic magmatism. The products of this magmatic episode are found as basaltic lavas and pyroclastic rocks in the Şenköy Formation, which was deposited in an extensional basin, or as intrusives cutting Variscan crystalline basement rocks. The Olur (Erzurum) region in the easternmost part of the Sakarya Zone is one of the few locations where contemporaneous acidic rocks crop out, exposed in an area of ~50 km 2 . The acidic rocks in the eastern Sakarya Zone consist of dacitic lavas, rare pyroclastic rocks, and very rare pebble dikes. Porphyries and trondhjemites are their intrusive equivalents and crop out as dikes and small stocks within the underlying Variscan basement. These Early Jurassic rocks have modal K-feldspar contents of <10% and are trondhjemitic in character. Laser ablation–inductively coupled plasma–mass spectrometry U-Pb dating of zircons from two samples yielded formation ages for these rocks of 185.3 ± 1.0 and 184.1 ± 1.1 Ma (±2σ). Geochemically, the rocks are strongly peraluminous and display a medium- to low-K affinity and sodic compositions (K 2 O/Na 2 O = 0.03–0.49). Enrichment in large-ion lithophile elements and depletion in Nb, Ta, P, and Ti are regarded as signatures of a subduction-related setting. Moderately radiogenic I Sr ratios (0.70508–0.70877) and depleted mantle-like Ɛ Nd (t) values (−0.6 to +3.0) and Pb(t) isotopes suggest that the acidic rocks were derived from juvenile lower crust. Geochemical and isotope data imply that the partial melting of juvenile mafic lithologies of the lower crust produced K-poor tonalitic melts that later fractionated to trondhjemitic melts while ascending to the surface. Considering the available data, we suggest that the Early Jurassic bimodal magmatic rocks of the eastern Sakarya Zone were formed in a back-arc setting during the southward subduction of the Paleotethys oceanic lithosphere. These rocks are a prime example of the formation of shallow subduction products following Late Triassic ridge subduction.
- MakaleYalnız künye2017Cordierite-bearing strongly peraluminous Cebre Rhyolite from the eastern Sakarya Zone, NE Turkey: Constraints on the Variscan Orogeny
Dokuz, Abdurrahman; Külekçi, Elif; Aydinçakir, Emre; Kandemir, Raif; Alçiçek, M. Cihat; Pecha, Mark E.; Sünnetçi, Kadir
The Cebre Rhyolite with an outcropping area up to 12 km(2) is one of the rare extrusions in the Variscan basement of the Sakarya Zone. The unit consists of high-K calc alkaline rhyolites (SiO2 = 74-82 wt.%). Abundant phenocrysts of quartz and K-feldspar are accompanied by subordinate cordierite phenocrysts, rare muscovite microphenocrysts and biotite microcrysts set in a fine-grained groundmass. Three types of rock fragments (xenoliths) have been recognized; (i) porphyritic, (ii) equigranular hypabyssal and (iii) hypocrystalline fragments. Zircon U-Pb dating indicates that the Cebre Rhyolite was extruded at 332.8 +/- 4.38 Ma, which post-dates the Variscan low temperature metamorphism and pre-dates the emplacement of I-type granitic intrusions (325-303 Ma).The samples are strongly peraluminous with A/CNK values ranging from 1.48 to 2.95 and A/NK from 1.49 to 2.99. They have very high K2O (3.72-7.42 wt.%) and Al2O3 (10.77-14.11 wt.%) contents, but very low CaO (0.02-0.21 wt.%), Na2O (0.05-0.78 wt.%) and MgO (0.3-0.21 wt.%) contents. The samples show geochemical affinity with the upper continental crust, e.g., enrichment of large ion lithophile elements (LILEs; K, Rb, U, Th, Pb), depletion of high field strength elements (HFSEs; Nb, Ta, Ti), Sr, P and Eu, but epsilon Nd-(t) values (- 3.06 to - 8.75) and isotope ratios of Sr-(t)((87) Sr/Sr-86 = 0.70499-0.70915) and Pb-(t) (Pb-206/Pb-204 = 16.41-17.570, Pb-207/Pb-204 = 15.54-15.59, Pb-208/Pb-204 = 36.20-37.22) are similar to those of the lower crust. Geochemical and isotope data indicate that the Cebre Rhyolite was generated by melting of metapelitic rocks with some addition of intermediate metaigneous derived magma. As a geodynamic model, we propose that the Variscan Orogeny in Turkey was occurred by collision of Gondwana with an arc/terrane separated from the southern margin of Laurussia. This collision was followed shortly after by splitting of oceanic lithosphere into two pieces and sinking down into asthenosphere. Rapid upwelling of asthenosphere to space emptied by previous oceanic lithosphere provided heat for high temperature metamorphism and anatexis of metasedimentary rocks in the crust. (C) 2017 Elsevier B.V. All rights reserved.