Characterization, technological properties, and ceramic applications of Kastamonu alluvial clays (Northern Turkey) in building materials

Abstract

This research investigates two unexploited Pınarbaşı (PC) and Küçüksu (KC) alluvial clays from Kastamonu province in the Black Sea region (Northern Turkey) and studies their potential applications in building materials. We have characterized the samples regarding their chemical and physical properties, spectrometry, thermal behavior, phase, and microstructure. This study also explores the technological features of heated clays at 900–1100 °C (such as ceramic properties and color), dilatometry, phase, and microstructural analyses. The results show that both clays contain quartz, kaolinite, illite, and calcite as dominant phases and some clayey minerals as minors. The chemical analysis indicates that the deposits are siliceous clays with the principal oxides of SiO2 (48.43–51.58 wt%), Al2O3 (17.92–20.87 wt%), and Fe2O3 (5.93–6.91 wt%). The KC clay shows a notably high surface area of 88.51 m2/g after N2-physisorption analysis. The characterization of heated clays demonstrates that the densification occurs by forming mullite and anorthite, which are responsible for the increased mechanical strength (24.84–32.85 MPa) above 1000 °C. The overall results reveal that both clays possess suitable technological characteristics, making them favorable low-cost sustainable raw materials in producing red-fired construction and building parts. Study shows that these reserves are typical representatives of other distributed natural clay resources in the area, which generally contain high iron or high carbonate substances. It is formidable that this work is helpful to cover a part of insufficient investigations on the clayey deposits of the Black Sea region.