Assessment of potentially toxic metal contents of clay bricks manufactured and utilized as structural building material in Türkiye

Abstract

Building material waste stored for long periods near agricultural lands and water resources may pose a danger to the environment and human health due to the toxic chemicals and metals they contain. Clay bricks (CBs), generally produced by mixing clay and water, are formed by firing the air-dried mixture to make them durable and stable. During firing, the CB suffers some chemical and physical changes and turns into a new artificial material. CBs, known as masonry units, have been one of the most used building materials throughout the history of construction. CB may naturally contain PTMs depending on the geochemical structure of the clay used in the production phase. In this study, major and minor oxides and PTM distributions in 45 CB samples collected from 31 CB factories that provide approximately one-third of the CB utilized in buildings in Türkiye were determined for the first time using an energy-dispersive X-ray fluorescence spectrometer. The average contents (in %, dry weight) of major and minor oxides in CB samples are in order of SiO (49.9) > AlO (17.8) > CaO (9.5) > MgO (8.2) > FeO (7.5) > SO (3.6) > NaO (3.3) > KO (1.8) > TiO (0.9) > PO (0.2) > MnO (0.1). The average contents (in mg/kg dw) of Fe, Ti, Mn, Cr, Sr, V, Ni, Zr, Zn, Cu, Co, Pb, and As in CB samples were analyzed as 52779, 5329, 736, 341, 233, 192, 190, 110, 85, 44, 39, 14, and 8, respectively. According to the enrichment factor results based on the Earth's crust average, it was revealed that Cr, Ni, and As were naturally moderately enriched.