Experimental investigation into the heavy metals content in construction materials

Abstract

This study investigates whether commonly used construction materials such as cement can contain potentially harmful accumulations of heavy metals. Cement is one of the places available to accommodate waste materials. Blast furnace slag, fly ash and many other waste materials can be added without affecting the strength characteristics of cement. Due to the hazardous constituents of some of these materials, concrete containing waste constituents may pose a threat to the environment as it is used, recycled, or disposed of. In this study, cement and cement ready-mixes, known in Austria as Beton, Estrich and Mörtel, were analysed by ICP-OES for selected heavy metals chosen for their risk to human, plant and animal health: cadmium; chromium; copper; nickel; lead; antimony; and zinc. The study employed a fluoric acid solution to ensure complete digestion of sample materials, with the aim of measuring total elemental content. Data was then compared with various reference concentrations for rough comparison estimation. The results showed that several of the samples have concentrations of these elements which are higher than the concentrations present in the Earth's crust. This suggests that the sampled materials may have potential to contribute to the enrichment of heavy metals in the environment. Chromium and nickel had lower concentrations in all samples relative to the reference data, suggesting that they do not pose a risk to the environment (although no differentiation was made in this study between Cr(III) and Cr(VI)). Cadmium, copper, lead, antimony and zinc all appeared in some samples in concentrations higher than the reference data. This suggests that these elements have potential to enrich the heavy metals content in the environment. However, the results for cadmium and antimony were problematic due to their relatively low concentrations relative to the ICP-OES determination limits, and would benefit from being re-examined by a method with lower detection limits such as Atomic Adsorption Spectrometry (AAS).