Thermophysical Characterization of Building Materials Due to Radioactive Decay

Abstract

This study aims to provide a thermophysical characterization of crushed stone, sand, brick, and cement due to radioactive decay. The 28 sand samples, 23 cement samples, 30 crushed stone samples, and 29 brick samples were analyzed by X-Ray Fluorescence (XRF) and Scanning Electron Microscope (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS) to screen samples for the presence of uranium, potassium, and thorium. Also high-purity germanium (HPGe) gamma spectrometers were applied to estimate 226Ra (as a proxy for the 238U decay series), 40K, and 232Th contents in ppm and to evaluate heat generation generated in the samples. For the samples, 226Ra ranges from 0.68 ± 0.04 to 21.7 ± 0.47 ppm, 40K ranges from 428 ± 92 to 37172 ± 1651 ppm, and 232Th ranges from 0.86 ± 0.11 to 171 ± 0.24 ppm. 21 sand samples, 19 cement samples, 29 crushed stone and stone dust samples, and 13 brick samples presented values ​​above the recommended average. The IH varied from 6.27×10-4 to 0.34, and the radiogenic heat production between the materials varied from 0.04 to 0.88 μW m-3, exceeding the average value ​​of 0.5 μW m-3 observed by Hansi Junior & Kusznir (2025). The temperature generated (Ttrmc) due to the radioactive decay of these materials in use in a standard room in a house was 7.54×10-5 °C. The value of the thermal power generated in the wall, the heat generation produced by the consumed mass, the linear power density, and the heat flux that passes through the wall surface from these materials were 3.65 μW, 1.98 nW kg-1, 0.46 µW m-1 and 0.23 µW m-2, respectively. The primary chemical components in the samples media are SiO2, Fe2O3, K2O and Al2O3. The crystal structures of samples typically consist of alternating Si-O tetrahedral layers and Al-O octahedral layers. The findings from this research will be useful to assess the radiation hazards of building materials in humans.

Keywords: gamma spectrometry, Radioactive Heat Production (RHP), XRF, EDX and SEM