NORM waste, cements, and concretes. A review

Abstract

The use of industrial waste and/or by-products as alternative sources of raw materials in building materials has become standard practice. The result, more sustainable construction, is contributing to the institution of a circular economy. Nonetheless, all necessary precautions must be taken to ensure that the inclusion and use of such materials entail no new health hazard for people or their environment. Due to the processes involved in generating industrial waste/by-products, these alternative or secondary materials may be contaminated with heavy metals, other undesirable chemicals or high levels of natural radioactivity that may constrain their use. In-depth and realistic research on such industrial waste is consequently requisite to its deployment in building materials. This paper reviews the basic concepts associated with radioactivity and natural radioactivity, focusing on industrial waste/by-products comprising Naturally Occurring Radioactive Materials (NORM) used in cement and concrete manufacture. Updated radiological data are furnished on such waste (including plant fly ash, iron and steel mill slag, bauxite and phosphogypsum waste) and on other materials such as limestone, gypsum and so on. The paper also presents recent findings on radionuclide activity concentrations in Portland cements and concretes not bearing NORMs. The role of natural aggregate in end concrete radiological behaviour is broached. The radiological behaviour of alternative non-portland cements and concretes, such as alkali-activated materials and geopolymers, is also addressed.

One part alkali activated materials: A state-of-the-art review

“…Their natural radioactivity, as such, should be determined to ensure their safety and to avoid any health and environmental issues. Constituents identified as NORMs include FA, GGBS, ACS, FS, SF, RM, volcanic tuff, and WG, to name a few [201]. Their radioactivity is determined from the concentration of natural radionuclide content, mainly 226 Ra (radium series), 232 Th (thorium series) and 40 K (potassium) [202].…”

The application of coal mining waste to the production of construction ceramics: radiological and mechanical aspects

“…The equipment used enables standard measurements of sample permeability for gas and tests including the effect of gas slip (19) so that even at low speeds, the gas flowing through the porous material behaves in accordance with Darcy's law. The obtained permeability coefficient can also be converted into filtration coefficient (k) for water (expressed in m/s) using the Equation [2]: [2] where: K P is the permeability coefficient (mD), γ is the specific gravity of liquid (N/cm 3 ) and η is the dynamic viscosity of liquid (Pa•s).…”

“…The waste from hard coal mining accumulated in landfills is a considerable burden for the local natural environment. The scale and extent of this phenomenon depends on many factors, including the amount and type of the waste, as well as its chemical composition and the content of heavy metals, the concentration of natural radionuclides, radon exhalation and other physical properties (2).…”

Hybrid Cements: Mechanical Properties, Microstructure and Radiological Behavior

“…Very few studies have been conducted on alkaline-activated cement and concretes (geopolymers) radiological behaviour [14,[36][37][38], but none whatsoever on the hybrid cement pastes and the relationship with their microstructure. Deploying a new method developed by the authors that uses solid 5 cm cubic specimens, the present research confirmed the existence of such a relationship in hybrid (70 wt% OPC + 30 wt% FA) cement pastes.…”