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The manufacture of Portland cement entails high energy and environmental costs, and various solutions have been implemented in recent years to mitigate this negative impact. These solutions include improvements in the manufacture of cement clinker or the use of supplementary cementitious materials (SCMs), such as fly ash (FA) or slag as a replacement for a portion of the clinker in cement. The incorporation of these SCMs in cement may increase its radiological content as they are naturally occurring radioactive materials (NORMs). The Activity Concentration Index (ACI) is a screening tool established in the European EURATOM Directive 2013/59 to determine the radiation protection suitability of a final construction material. The ACI is determined by the activity concentrations of 226Ra, 232Th and 40K, usually determined by gamma spectrometry. The methodology of gamma spectrometry is accurate and appropriate, but this technique is not available in all laboratories. For this reason, and taking into account that there is a relationship between the chemical and radiological composition of these building materials, a new approach is proposed to determine the radiological content of these materials from a chemical analysis such as X-ray fluorescence (XRF). In this paper, principal component analysis (PCA) is used to establish the relationships between the chemical composition and radiological content of cements, FAs, and slags of different natures. Through PCA it was possible to group the cements based on two variables: CaO content and Fe2O3–Al2O3–TiO2 content. A lower correlation was observed for the FAs and slags, as the sample scores were centered around the origin of the coordinates and showed greater dispersion than the cements. The clusters obtained in the HJ–Biplots allowed the determination, using multiple regression, of models relating the activity concentration of 226Ra, 232Th (212Pb), and 40K to the oxide percentages obtained for the three matrices studied. The m

To determine their transfer factors, activity concentrations of natural radionuclides were measured in the leaves and acorns of holm oak (Quercus ilex L.) trees collected from seven locations with different soil properties and radionuclide activity concentrations. The chemical and mineralogical compositions of the soils were also analysed to investigate the effect these had on radionuclide absorption by the trees. Soil chemistry showed significant effects on radionuclide incorporation into Quercus ilex L. tissues. A significant relationship was established between activity concentrations and soil content of Ca and P with 238U and 226Ra in the leaves and acorns of Quercus ilex L. Differentiated transfer was found for 40K, which showed greater transfer to the leaves than the other radionuclides. The activity concentration of U and 226Ra was higher in the fruits than in the leaves, with the opposite effect being observed for 40K. The risk of U and 226Ra transfer into the food chain through acorn consumption by livestock is predicted to increase in soils poor in Ca and rich in P.

In this study, the possible relationship between the chemical composition of different cements and fly ashes with their radiological activity has been studied using Principal Component Analysis (PCA). PCA allowed the cements to be grouped on the basis of two main factors, their CaO-SO3 content and their Fe2O3-Al2O3-TiO2 content. The latter factor was found to be the most correlated with the presence of natural radionuclides. The PCA showed a lower correlation for fly ash as the scores of the samples were centered showing a large scatter. However, the clustering shown by the PCA for the cements allowed to establish from multiple regression a model relating the activity concentration of 226Ra, 232Th (212Pb) and 40K with chemical composition.

Se han caracterizado tres granitos gallegos de tres canteras diferentes desde el punto de vista químico y radiológico, estableciendo las relaciones existentes entre la granulometría y composición química de los mismos con los valores de radioactividad natural obtenidos. Los tres granitos presentan valores de actividad superiores a los fijados en la Directiva europea 2013/59/EURATOM. Los resultados han mostrado claras diferencias en la radioactividad de los tres granitos y su influencia final en los morteros elaborados con ellos. En las condiciones ensayadas dichos morteros cumplen con los requisitos de la Directiva europea, Three Galician granites of three different quarries have been characterized from the chemical and radiological point of view, establishing the existing relationships between the granulometry and chemical composition of these granites with the natural radioactivity values obtained. The three granites have activity values higher than those set in the European Directive 2013/59/EURATOM. The results have shown clear differences in the radioactivity of the three granites and their final influence on the mortars made with them. Under the conditions tested, these mortars meet the requirements of the European Directive

The use of more eco-efficient cements in concretes is one of the keys to ensuring construction industry sustainability. Such eco-efficient binders often contain large but variable proportions of industrial waste or by-products in their composition, many of which may be naturally occurring radioactive materials (NORMs). This study explored the application of a new gamma spectrometric method for measuring radionuclide activity in hybrid alkali-activated cements from solid 5 cm cubic specimens rather than powder samples. The research involved assessing the effect of significant variables such as the nature of the alkaline activator, reaction time and curing conditions to relate the microstructures identified to the radiological behavior observed. The findings showed that varying the inputs generated pastes with similar reaction products (C-S-H, C-A-S-H and (N,C)-A-S-H) but different microstructures. The new gamma spectrometric method for measuring radioactivity in solid 5 cm cubic specimens in alkaline pastes was found to be valid. The variables involved in hybrid cement activation were shown to have no impact on specimen radioactive content. The powder samples, however, emanated Rn (a descendent of Ra), possibly due to the deformation taking place in fly ash structure during alkaline activation. Further research would be required to explain that finding.

Determinación del contenido radiológico en cementos eco-eficientes

Supplementary cementitious materials (SCMs) in industrial waste and by-products are routinely used to mitigate the adverse environmental effects of, and lower the energy consumption associated with, ordinary Portland cement (OPC) manufacture. Many such SCMs, such as type F coal fly ash (FA), are naturally occurring radioactive materials (NORMs). 226Ra, 232Th and 40K radionuclide activity concentration, information needed to determine what is known as the gamma-ray activity concentration index (ACI), is normally collected from ground cement samples. The present study aims to validate a new method for calculating the ACI from measurements made on unground 5 cm cubic specimens. Mechanical, mineralogical and radiological characterisation of 28-day OPC + FA pastes (bearing up to 30 wt % FA) were characterised to determine their mechanical, mineralogical and radiological properties. The activity concentrations found for 226Ra, 212Pb, 232Th and 40K in hardened, intact 5 cm cubic specimens were also statistically equal to the theoretically calculated values and to the same materials when ground to a powder. These findings consequently validated the new method. The possibility of determining the activity concentrations needed to establish the ACI for cement-based materials on unground samples introduces a new field of radiological research on actual cement, mortar and concrete materials.

The study reported the effect of granite sand on strength and microstructural developments in mortars prepare from OPC with a high coal fly ash (FA) content or from hybrid alkaline cements. The radiological behaviour of the resulting mortars was compared to materials prepared with siliceous sand (with particles sizes of <2 mm) and the relationship between such radiological findings and mortar microstructure and strength was explored. A new method for determining natural radionuclides and their activity concentration Index (ACI) on cement mortars (specifically to solid 5-cm cubic specimens) was applied and validated. The microstructural changes associated in mortars have no effect on mortar radiological content measurements. The mortars with granite sand exhibited very high ACI > 0.96, which would ultimately limit their use. A conclusion of interest is that where information is at hand on the starting materials (OPC, FA, sand, admixtures), their pro-portions in the mortar and the mixing liquid content (water or alkaline activators) their radiological content is accurately predicted. The inference is that a mortar’s radiological content and ACI can be known prior to mixing, providing a criterion for determining its viability. That in turn lowers environmental risks and the health hazards for people in contact with such materials.

Although primarily deemed to be an ornamental stone, granite may also be ground into fines for use in cement mortars, where it exhibits high strength and durability. Both the 40K present in the stone and the natural decay series of its uranium, thorium and actinium components exhibit high activity concentrations. An understanding is therefore needed of the correlation among the different particle sizes in granite aggregate to assess their con tribution to a mortar’s activity concentration index (ACI). This study analyses the variation in ACI with particle size in three types of granite based on the chemical, mineralogical and radiological characterisation of five size fractions. The activity concentrations of the tho rium and uranium natural decay series were highest in the finest fractions. A correlation was observed between thorium and the MgO and Fe2O3 normally present in mica group phyllosilicates. In two of the three granites, the mortars prepared with the smallest size particles had ACI values >1.

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.

The purpose of this work was to study the factors affecting the absorption of U by plants growing on the spoil tip of an abandoned mine in western Spain. The plant species were selected based on how palatable they were to livestock and were sampled for four consecutive years during which, we also recorded rainfall data. The factors related to the plants studied were the leaf size and the percentage and characteristics of the arbuscular mycorrhizae (AM) fungi present in their roots. Our results showed a correlation between the annual rainfall and the U concentration in the plants. The percentage of mycorrhization and AM vesicles is a predominant factor in the uptake of U by plants. Spergularia rubra (L.) J.Presl & C.Presl, which is resistant to mycorrhization, contained higher U concentrations relative to the plants that grew with AM mycorrhization. The absorption curves of the different plants studied indicated that these plants were tolerant to 238U from 875 Bq kg−1 (70 mg kg−1), with a hormesis effect below that concentration. The annual U removal was 0.068%, suggesting that AM are responsible for limiting the incorporation of U into the food chain, favouring its retention in the soil and preventing its dispersion.

This study explores the effect of 229Th tracer tail interference on the determination of the sensitivity of 230Th alpha spectrometry of samples with environmental levels of radioactivity. Tracer peak tail interference was calculated with Suma-Alpha, whilst Visual Basic for Applications (VBA in Excel©) software was used to study the variation in sensitivity in terms of the amount of tracer added. Unnecessary increases in the amount of tracer or extended sample measuring times were observed to have adverse effects on method sensitivity (Detection Limit- Ld).

Pursuant to European Directive 2013/59, materials additioned with NORM waste must be characterised radiologically to determine their acceptability for use in construction. The radionuclides studied to judge that acceptability, 232Th, 226Ra and 40K, are normally measured with gamma spectrometry. Gamma detectors are calibrated by using standards as similar as possible in dimensions and chemical composition as the matrix in the samples to be measured. In light of the broad spectrum of chemical and physical characteristics of NORM samples, experimental calibration is often beyond the means of gamma spectrometry laboratories. As a result, Monte Carlo-based methods are deployed to simulate the experimental setup consisting in detector and sample, both geometrically and chemically. Canberra Industries’ LabSOCS (Laboratory Sourceless Calibration Software) is one of the tools available for such calculations. This study verified the accuracy and precision of the counting efficiency delivered by LabSOCS, both with the standard powder geometry and a new geometry consisting in a 5 cm cubic specimen of Portland cement paste. The findings showed that in both geometries the accuracy and precision of LabSOCS-calculated efficiency (by specimen height and activity), across an energy range from 45.64 keV (210Pb) to 1460.82 keV (40K) met the acceptability criteria routinely applied in environmental radioactivity laboratories. The geometry proposed yielded activity values for the end construction material closer to the true indices than the conventional method consisting in summing the partial activities of the unreacted components.

[EN] The establishment of a screening index would be a powerful tool to decide whether abandoned uranium mining areas should be rehabilitated or decommissioned. Thus, in this work we established a radiological index which uses the activity concentrations of different groups of gamma emitters from the natural radioactive series of 238U, 235U, and 232Th, as well as 40K and 137Cs. These activity concentrations were calculated by using the absorbed gamma radiation dose value of 175 nGy h−1 specified in the U.S. Code of Federal Regulations. We studied our index in an abandoned uranium mining area in Salamanca, Western Spain, and found that the most influential factors in this area were the presence of organic matter in the soil and the possible effect that plants and fungi may have on the retention of these aforementioned radionuclides. In addition, the results showed that contaminants are migrating in an easterly direction in line with the prevailing wind direction and we were able to identify areas in which the radiological risk is likely high. The mean effective dose rate was 2.51 ± 0.98 mSv y−1 which was equivalent to the levels obtained in previous works., [ES] La determinación de las concentraciones de actividad de los diferentes radionucleidos en las áreas abandonadas de la minería de uranio es necesaria para conocer los niveles de radiación y a partir de ellos, decidir si es o no necesaria su rehabilitación. En este trabajo se ha establecido una metodología que permita conocer el verdadero impacto radiológico ambiental a partir de las concentraciones de actividad de diferentes grupos de emisores gamma pertenecientes a las series radiactivas naturales del 238U, 235U y 232Th. Los valores obtenidos han permitido comprobar la dispersión de la contaminación en función de la rosa de los vientos así como la zona que supone un riesgo radiológico importante. El factor más influyente en la zona estudiada ha sido tanto la presencia de materia orgánica como la posible acción de las plantas en la retención de los radionucleidos estudiados.

The use of admixtures in mortars to improve both their physical-chemical and ornamental features has become increasingly common in recent years. The varying origin and composition of these products, some sourced from waste produced in other industries, poses the question of whether they modify the activity concentration index (ACI) of the construction materials to which they are added. Seven pigments, some of natural and others of artificial origin, and two water repellents were characterised both chemically and radiologically in this study. Neither the synthetic pigments nor the water repellents exhibited significant radiological content. The pigments based on Fe2O3 of natural origin had detectable activity concentrations of naturally occurring radionuclides from the 238U series. Those levels were attributable to the raw material used, namely the bauxite red mud generated in aluminium production. In addition to Si, Al, Fe, Ca, Ti and Na as majority elements, this sludge also contains traces of K, Cr, V, Ba, Cu, Mn, Pb, Zn, P, F, S and As, among others, including naturally occurring uranium. The public and occupational radiological risk due to exposure to pigment-modified construction materials were consequently assessed. Neither the doses for the public at large and for workers were found neither to be significant nor constitute any perceptible hazard, essentially in light of the small amounts of pigment used to prepare mortars.

Chemical, physical, mineralogical and radiological characterization of olive biomass fly ash (OBFA) and bottom ash (OBBA) was main objective to determine their potential use as alkaline activators in the preparation of alkali-activated materials or geopolymers. Water solubility tests showed that they released K and Na ions, affording a high pH and alkaline content. Pastes made with 70 wt% vitreous blast furnace slag (SL) and 30 wt% of OBFA or OBBA yielded alkali-activated materials with 28 days mechanical strength of 33 to 18 MPa. In pastes prepared with 30 wt% OBFA, strength values were comparable to those developed by slag pastes activated with a commercial KOH. However, the pastes made with 70 wt% coal fly ash and 30 wt% OBFA or OBBA proved to be inviable because the pH reached was not high enough to activate the precursor. The radiological calculations of OBFA- and OBBA-SL bearing pastes would conform to European legislation on protection against exposure to ionising radiation, for the activity concentration index (ACI) found in the final product was less than 1 in all cases. The pastes leached primarily K. The presence of elements such as 210Po and 210 Pb at the end of the decay chain in the eluates would not limit the use of biomass ash and slag blends. These findings have confirmed the feasibility of using olive oil biomass ashes as an alternative alkaline activator in blast furnace slag systems to produce alkali-activated materials or geopolymers, with properties that make them apt for use as building materials.

Granites are rocks formed primarily by the minerals quartz, feldspar and mica, but they also contain varying amounts of natural uranium (238U) and thorium, which are a source of natural radioactivity. In Spain, certain areas of the Sierra de Madrid and the Galician area are rich in this type of rocks, which are used not only as stones in construction, but also as aggregates in the preparation of mortars and concretes. Directive 2013/59 / EURATOM establishes the limits of natural radioactivity that come from building materials. Therefore, given the uranium content of the granites, their radiological control addresses special importance. In the present study we have studied natural radioactivity of Portland cement mortars made with granite sand. For this purpose, three granitic aggregates of different origin have been characterized chemically, mineralogically and petrologically. The natural radioactivity of the three granitic aggregates with three different granulometry has been determined through gamma spectrometry. Likewise, OPC mortars have been prepared with the fine fractions of granitic aggregates (<4 mm) establishing both the activity indexes of these mortars and their relationship with the chemistry and mineralogy of granitic aggregates. As a general result, it is observed that the radioactivity indexes of each of the components additively affect the overall radioactivity of the Portland cement mortar.

The generation of high quantities of waste produced by the metallurgical and food industries - in particular slags and biological or biomass ashes - makes us rethink in its possible re-use as alternative raw materials to possibly use them in construction or civil engineering. The quantification of the major chemical and radioactive elements in: the raw materials used, blends with different percentages of raw materials and the leachates from the extraction studies to assess their behavior in the final phase of their environmental cycle, allows us to optimize the material and know the possibilities of eliminating the waste of these industries. These wastes used in construction are limited by both their radioactive content (directive EURATOM 2013/59) and their content of unhealthy leached elements. This paper presents the advantages and disadvantages that the use of the incorporation of slag and olive fly ash and bottom ash biomass in construction materials from the point of view of the presence of these elements from radiological and leaching behaviours.

Partial or total replacement of Portland cement clinker by SCMs (Supplementary Cementitious Materials) is a priority for the cement industry in its pursuit of global sustainable development and eco-friendly binder manufacture. The most widely used SCMs include industrial by-products such as blast furnace slag, fly ash and red mud. Alkali-activated cements manufactured with SCMs may reduce the need for Portland clinker by up to 90 wt%–100 wt% with no significant decline in material strength. The trade-off, however, is the risk of higher than legally allowable levels of radioactivity and unbound heavy metals (Cd, Hg, Ni, Pb, Cr), which may leach into the soil with the concomitant adverse implications for human health and the environment. This study assessed the mechanical strength, leachability and natural radioactivity of alkali-activated cement paste containing industrial waste-based SCMs (blast furnace slag, fly ash and red mud) and Pb and Ni compounds. Strength was highest in alkali-activated slag and slag/fly ash pastes and lowest in the red mud-containing materials. The addition of Pb or Ni sulphates had no adverse effect on this parameter. Alkaline and OPC pastes showed a high level of immobilization of both lead and nickel ions. According to the radiological findings, the Activity Concentration Index (I) was higher in red mud than in OPC, blast furnace slag or fly ash. With (I) values lower than 1, however, all the hydrated/activated materials studied would be EU directive-compliant. Nonetheless, the use of these new materials will depend not only on the activity concentration index, but also on their physical and chemical properties and the quality tests that must be passed to conform to legal requirements.

Since 2000, CIEMAT (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas) is carrying out the PIMIC Project (Integral Plan for the Improvement of CIEMAT Facilities) for the decommissioning & dismantling of old nuclear and radioactive facilities and the potentially radiologically impacted areas and buildings. PIMIC activities involve the generation of waste materials with various physical, chemical and radiological properties, which must be characterized in order to be properly managed and comply with current regulations. Radiological characterization of these waste materials may lead to their classification as radioactive waste, in which case the “Plan de Gestión de Residuos Radiactivos del CIEMAT”[1] and their removal by ENRESA, the public company that manages the radioactive wastes generated in SPAIN applies [2, 3]. However, a large fraction of these waste materials with low radioactive contents are likely to be managed as conventional waste without further radiological control, through the so called Decommissioning Process. The optimization in the production of waste materials as well as their minimization are key factors for the process due to their significant economic, social and environmental impacts...