Challenges and opportunities of terahertz technology in construction and demolition waste management

Construction and demolition waste are one of the largest waste streams generated in the EU by volume. They consist of materials such as concrete, bricks, gypsum, wood, glass, metals, foams, plastics, solvents, asbestos, asphalt, and excavated soil. Nowadays, many of them can be recycled, some even endlessly. This research attempts to contribute to the non-destructive characterization of such a waste with a novel method using terahertz radiation. By combining terahertz imaging and spectroscopy, we performed analytical characterization of selected building materials. The results demonstrate that terahertz technology allows an inside view into some of the non-conducting building materials. THz imaging can detect and visualize the organic solvents in the insulation material, which are often disposed of together with construction and demolition waste. It can also visualize the content of foreign objects or hazardous and toxic substances, which is important for their separation in the recyclate according to the type of the material. Furthermore, THz spectra reveal some spectral lines that can differentiate between different plastics and polymers within the frequency range of 1.0-4.5 THz due to different material structures and chemical compositions. Such results significantly contribute to the decision of which product meets all the standards, which can be returned to the production process due to irregularities or may be disposed of as waste. The only way to reduce construction and demolition waste in the future is to encourage the adoption of innovative technologies like terahertz spectroscopy in combination with traditional methods. This approach can bring some changes also to the construction design philosophy toward more sustainable buildings with minimum end-of-life demolition.

Potential of biochar use in building materials

A critical review of the articles dealing with biochar in terms of the reuse of biomass waste in building materials and its impact on material properties was conducted using five different electronic databases; thirteen articles were selected for this critical review. Biochar was used as a replacement for cement and aggregate in cementitious composites and as an addition in wood polypropylene composites and plasters. The biochar dosages ranged from 0.5% to 40%; in most composites, the addition of biochar increased strength and reduced thermal conductivity and the bulk density of fresh mortars. Also, biochar dosages of 0.5-2% decreased, while dosages of 10-40% increased water absorption and penetration on cementitious composites. The selected studies mainly introduced biochar use in building materials as a means of biomass waste reduction and its reuse for various purposes, while carbon footprint reduction was addressed in only a few of them. Biochar-containing building material's capability of capturing CO₂ from the air was also observed (0.033 mmol CO₂ g_biochar^-1 to 0.138 mmol CO₂ g_biochar^-1). The results also showed that mortars with CO₂-unsaturated biochar had better mechanical and physical properties than mortars with CO₂-saturated biochar. Selected studies showed biochar-containing building materials have a great potential for carbon footprint reduction. However, there is a lack of comprehensive studies about biochar use in building materials concerning climate change mitigation.

Redispersible polymer powder modified cementitious tile adhesive as an alternative to ordinary cement-sand grout

With the advent of technologies on modern structural and building materials, adaptation of such technological features has been the pivotal concern of researchers. Ceramic tiles attained a distinctive focus due to its decorative feature for both indoor and outdoor conditions and also for their ease of implementation. The purpose of exploiting ceramic tiles is not only to impart structural strength but also the aesthetical characteristics that seem to matter a great deal. When it comes to the adhesion of these tiles onto the substrate wall, traditional method exerts the use of sand-cement grout. This faces some drawbacks including poor water retention property, hard and brittleness of the surface, much higher drying time, no flexibility, higher thickness of the paste and so on. These difficulties can be overcome by the addition of redispersible polymer powder (RPP) along with other cementitious constituents. The blended polymers interact with cement components to improve the physical and mechanical properties such as increased adhesion strength, reduced shrinkage and lower water absorption. This review article made an effort to provide the generalized idea about the cementitious tile adhesive (CTA) and its components. Focus was made onto the commercially available RPP and formulation of CTA with the inclusion of RPP. Critical analysis of the repercussions of RPP fortification was also carried out based on different researcher's findings.

Potential re-use of sewage sludge as a raw material in the production of eco-friendly bricks

Wastewater (sewage) treatment plants generate a high volume of sludge that, although it is classified as class II-A (not inert) non-hazardous waste, is commonly disposed of in sanitary landfills. Hence the environmental urge to assess its valorization possibilities. The present study describes the use of a sewage sludge as raw material in the production of red ceramic bricks by extrusion, focusing on the technological changes brought about by the presence of the sludge during the plastic forming process, in terms of the plasticity of the mixture and its subsequent extrudability. To quantitatively identify the best moisture conditions for the extrusion of high-quality products, shear strain amplitude sweep (torsional) tests were conducted on green (moist) prismatic samples produced with different moisture and sludge contents. For sewage sludge contents up to 10 wt%, the optimal moisture content was identified at 31-33 wt%. Higher water demand was identified for 15 wt% of sludge, for which optimal extrusion results required 35 wt% moisture. The total linear shrinkage after drying and firing, as well as the water absorption, were within the limits required for ceramic bricks for all the sludge contents. The results for compressive strength of the fired bricks also demonstrate that the incorporation of up to 15 wt% sewage sludge into the clay mixture is highly feasible for the production of extruded ceramic bricks.

Analysis of biochar-mortar composite as a humidity control material to improve the building energy and hygrothermal performance

This study suggests a new perspective of biochar as a building material that improve not only for the strength but also hygrothermal properties. Biochar has a high porosity and surface area created by pyrolysis. It can be suitably used as a porous material because porous materials are used by incorporating into building materials for improving hygrothermal performance in the construction sector. To analyze whether biochar can be used as a functional building material to improve the hygrothermal performance, two types of biochar, made from oilseed rape (OSB) and mixed softwood (SWB), were prepared. A biochar-mortar composite was prepared according to the mixing ratio of the biochar from 2 wt% to 8 wt%, and the compressive strength and hygrothermal performance of them were analyzed. The compressive strength is the highest when 4 wt% of biochar into the mortar was mixed regardless of the type of biochar. Thermal conductivity of biochar-mortar composites was decreased as the biochar addition increased, and the value of biochar-mortar composites with 8 wt% OSB decreases by maximum 57.6% compared to the conventional cement mortar. The water vapor resistance factor of biochar-mortar composites increases, and biochar-mortar composites with 8 wt% SWB increases by maximum 50.9% compared to the reference. WUFI simulation shows that the biochar-mortar composites can contribute to a humidity control and no mold growth. The biochar-mortar composites can also contribute to energy savings although the amount of savings is insignificant. As a result, this study proved that when the mortar with biochar addition was possible to improve not only strength but also hygrothermal properties of mortar. This approach will be a new perspective that biochar can apply to the building material in practice.

Risk assessment of asbestos containing materials in a deteriorated dwelling area using four different methods

The release of asbestos fibers in old buildings, during demolition, or remodeling is associated with severe public health risks to building occupants and workers. In Korea, asbestos was used in several building materials during the 20th century. Although the use of asbestos is currently banned, its widespread earlier use and the current government initiatives to revitalize dilapidated areas make it essential to accurately evaluate the location and status of asbestos-containing materials (ACMs). This study surveyed buildings in an area of deteriorated dwellings targeted for renewal and determined the status and distribution of ACMs in that area. Asbestos distribution maps were generated and asbestos characteristics were analyzed. In addition, the risk posed by the identified ACMs was assessed using four international methods (the Korean Ministry of Environment, US Environmental Protection Agency, American Society for Testing and Materials, and UK Health and Safety Executive methods), and the results were compared. Notable differences between the assessment results were identified and were found to reflect the specific characteristics of buildings in the study area. These findings suggest ACM risk assessments should be specifically tailored to the regions in which they are applied, thereby improving ACM management and promoting both worker and occupant health.

Evaluation of thermal properties and acetaldehyde adsorption performance of sustainable composites using waste wood and biochar

In order to vitalize the use of wood, which is a sustainable resource, increase the utilization of resources through the recycling of wood waste, and reduce environmental pollution in the waste disposal process, biocomposite was manufactured by using biochar which can be produced with wood waste and is effective in carbon isolation. The thermal characteristics and acetaldehyde adsorption performance of the prepared biocomposite were evaluated based on the pore characteristics, surface functional groups, crystal structure, and elemental analysis results of the biochar. As a result of the experiment, as the content of biochar increased, the thermal conductivity of the biocomposite decreased and the specific heat was not affected. The acetaldehyde concentration tended to decrease as the content of biochar increased, adsorbed up to 4.4685 ppm of acetaldehyde more than the reference. From these results, it is judged that the biocomposite produced in this study can function as a sustainable composite that uses waste wood to improve indoor air quality and satisfies the performance as a building material.

Modeling VOCs emission/sorption with variable operating parameters and general boundary conditions

An integrated model of VOCs emission/sorption from/on dry building materials with a general boundary condition, variable air exchange rate and inlet concentration is developed. An analytical solution is obtained by using the generalized integral transform technique. Good agreements are obtained between the present model and the experimental data. The effects of environmental conditions on the emission are investigated. The emission from two surfaces can increase the concentration of hexanal in the air and decrease the initial emission rate at x=δ with the increase in mass transfer coefficient at x=0. Periodical inlet concentration can lead to the periodic variation of materials between a source and a sink. Ventilation can keep the concentration in the air at a low level and help to decrease the concentration of hexanal in materials. The present model is capable of simulating indoor air quality due to the VOCs emission and sorption.

Evaluation of hygrothermal performance of wood-derived biocomposite with biochar in response to climate change

Wood is a sustainable resource and building material. It provides an excellent response to climate change and has excellent insulation performance. However, structural defects may occur due to decay from moisture, resulting in poor dimensional stability. The rich organic substances contained in wood can lead to mold when the moisture content is consistently high, adversely affecting the health of occupants. Therefore, we attempted to compensate for the disadvantages of wood in regard to water stability while maintaining the high thermal insulation performance and carbon dioxide storage capacity, using biochar from thermally decomposed spruce under oxygen limiting conditions. A wood-derived biocomposite was prepared by mixing biochar and soft wood-based chips using the hot-press method, and the thermal conductivity, specific heat, water vapor resistance factor, moisture adsorption, and moisture desorption performances were analyzed. The thermal conductivity of WB10 with 10 wt% biochar content was 0.09301 W/mK. This is a 7.98% decrease from 0.10108 W/mK, the thermal conductivity of WB0 without biochar. The water vapor resistance factor tended to increase when the biochar ratio increased. As the proportion of biochar increased, the equilibrium moisture content in high relative humidity tended to decrease, and it was found that the moisture adsorption and desorption performances were affected by the ratio of the biochar. Therefore, wood-derived biocomposites using biochar can be used in environmentally friendly materials, with improved thermal insulation performance and water stability.

Application of material from used car tyres in geotechnics-an environmental impact analysis

This work begins with a literature-based discussion of the hazardous-waste problem represented by car tyres as hazardous waste, along with possible ways in which they might be utilised or managed. The impact of the material on the environment is characterised in the process, not least in the context of pollutants leached to the aquatic environment. Input in terms of new research results concerns the impact on water and soil of material from used car tyres being used in geotechnics. Specifically, tyre bales comprising 100–140 car vehicle tyres compressed into a lightweight block and secured by galvanised steel tie wires running around the length and depth of the bale, were researched, having been immersed in basins with alkaline and acidic water following initial preparation and pre-washing. The aim was to in some sense simulate—respectively—conditions in which rain and surface/ground water are involved, or else acid rain. To do that, the tyre bales were placed in the water for 120 days, with emerging leachate analysed after set intervals of time, with a view to changes in key physicochemical parameters of water being noted, as well as signs of the leaching of both undesirable components and priority substances, from tyres into the aqueous medium. Washing of the tyre bales was shown to induce slight pollution of water, with limited exceedance of normative values in respect of OWO content. However, this increase was not due to leaching of the Persistent Organic Pollutants tested for, but may rather have reflected contamination of tyres used, e.g., of soil at the place of previous storage. In general, waste water arising does not therefore contain substances that would stand in the way (legally) of its being discharged into a combined sewer system. Similar conclusions were arrived at through analysis of the leaching of pollutants from tyre bales exposed in the aforementioned pools of water of neutral and acidic reaction. Wastewater arising was not enriched significantly in impurities (be these metals, PAHs, phthalates, selected anions or cations), and there were therefore no exceedances of standards imposed for wastewater discharged to either waters or soil.

Very Low Concentration Adsorption Isotherms of Trichloroethylene on Common Building Materials

Building materials that are found in the indoor environment can play an important role in determining indoor air quality. Previous studies have recognized that building materials are potential sinks/sources of indoor volatile organic compounds (VOCs), but their uptake under extremely low concentrations has not been extensively studied. This study has characterized the capacities of various building materials for adsorption of trichloroethylene (TCE), which is a contaminant of significant concern in vapor intrusion scenarios. The capacities of more than 20 building materials were established at a TCE concentration of 1.12 ppbv (and for selected materials at concentrations up to 12.5 ppbv). This was achieved using a thermal desorption method. Room temperature isotherms for glass wool, polyethylene, nylon carpet, drywall, printer paper, leather, and cinderblock were measured. The results showed that the sorptive capacities of the building materials were at nanograms per gram levels; cinderblock had the largest sorption capacity among all the building materials tested and this is believed to indicate that solid carbon content of materials plays a significant role during the sorption process. TCE desorption from selected building materials was also investigated at room temperature and 100°C.

Potential radiological impact of the phosphate industry in South Africa on the public and the environment (Paper 1)

Phosphate rock is mined on a large scale as a source material for fertilizers and other phosphorous containing products, such as phosphoric acid and gypsum. The potential problem of high concentrations of naturally occurring radionuclides in the phosphate industry has been recognized for many years. The industry is responsible for the production of millions of tons of phosphogypsum waste, which is usually stockpiled and might impact the surrounding environment. The presented study aims to assess the natural radioactivity concentrations in raw and waste sub-products from phosphate mining and fertilizer production in South Africa and determine the potential radiological risk associated with the industry. Activity concentrations of ²³⁸U, ²²⁶Ra and ²³²Th in phosphate rock, phosphogypsum, tailings, fertilizer, soil and sediment were found to be similar to values reported in previous studies conducted in South Africa. Concentrations of the ²³²Th decay series were higher than those of the ²³⁸U series in rock and ore. The low concentrations of ²³⁸U and ²²⁶Ra in rock and ore, compared to other countries, makes it more suitable to be used for fertilizer production, and therefore increases the demand for export of rock phosphate and fertilizer from South Africa. ²²⁸Ra concentrations in phosphogypsum were higher than ²²⁶Ra. The activity of ²²⁸Ra was also enriched compared to ²³²Th, with a ratio of 0.45-19.8. Similar equilibria as described in literature were observed, with almost all the ²²⁸Ra and ²²⁶Ra present in the phosphate rock observed in the phosphogypsum. Only a low percentage of ²³²Th present in the original rock remained in the phosphogypsum, with more than 60% present in the fertilizer. The activity concentrations of all nuclides in the analysed samples from the phosphate industry were less than the 1000 Bq kg^-1 exclusion value proposed internationally for regulation of NORM. With the exception of phosphate rock samples, concentrations in all solids were lower than the 500 Bq kg^-1 limit proposed by the National Nuclear Regulator in South Africa. The obtained values of Ra_eq for all phosphogypsum, tailings and soil samples were less than the recommended limit of 370 Bq kg^-1. The gamma index for the majority of samples was less than 0.5. The index exceeded the limit of unity only for phosphate rock and fertilizer samples, indicating some radiological risk to people living in the vicinity of the industry. The results suggested that members of the public were unlikely to receive any significant dose from the use of phosphate rocks and fertilizers, with an annual effective dose of less than 0.5 mSv.a^-1. The highest external dose of 0.45 mSv a^-1 is expected from phosphate rock. The suitability of use of phosphogypsum as building material was evaluated. Based on the calculated gamma index [I_γ = 0.52 ± 0.14] use of phosphogypsum as building material is permitted.

An improved mechanism-based model for predicting the long-term formaldehyde emissions from composite wood products with exposed edges and seams

Emissions of formaldehyde from building materials and furniture can cause adverse health effects. Traditional models generally only consider emissions as a physical process that can be characterized by three key parameters: the initial emittable concentration, the diffusion coefficient and the partition coefficient. However, the physical-based model causes discrepancy in predicting long-term formaldehyde emissions for the cases where chemical reaction (i.e., hydrolysis) occurs over time. In this study, an improved mechanism-based model was developed by combining the chemical reaction process with a physical mass transfer process to more accurately predict the long-term emission behaviors. The chamber testing data of formaldehyde emissions from exposed edges and seams of a laminate flooring product made with composite wood core for about 1.5 year was used to validate the model. Results indicate that the mechanism-based model characterizes well the long-term formaldehyde emissions from the tested material. Predictions of different models further demonstrate the advantages of this improved model compared with the physical model or with empirical models. This study is the first attempt to check the feasibility of including the chemical reaction term in emission modeling and to quantitatively explore the importance of its contribution to long-term formaldehyde emissions, which includes most of the indoor emissions from materials and furniture.

Quantifying factors related to urban metal contamination in vegetable garden soils of the west and north of Melbourne, Australia

Vegetable gardens in cities provide communities with fresh vegetables but also may contribute towards public exposure to metals present in soil from historical pollution. Contamination of some Melbourne garden soils with Pb (range 12.9-773 mg kg^-1 in soil) was found with some soils exceeding the Australian human health screening criteria for residential land use of 300 mg kg^-1. Cadmium concentrations (0.12-1.04 mg kg^-1) were above the ambient background soil concentrations of <1 mg kg^-1. Nickel concentrations (7.6-40.5 mg kg^-1) and Cr (11.6-49.4 mg kg^-1) were within the range of expected ambient background concentrations. Distance from the nearest arterial road, house age and the likely use of lead-based paints were the main factors explaining approximately 75% of soil Pb variability in garden soils. Metal concentrations in garden soils of wooden houses were found to be significantly higher than the garden soil of brick and concrete houses (Pb (p < 0.0001)) and Cd (p < 0.001)). Significant correlations were found between backyard garden soil metal concentration and house age for Pb (R² = 0.83, p < 0.0001) and Cd (R² = 0.40, p < 0.0002) and the distance from arterial roads for Pb (R² = 0.38, p < 0.002), while Cr and Ni are related to soil characteristics cation exchange capacity, organic matter, and pH. Vegetable garden with elevated Pb and Cd had recognizable risk factors such as older, painted structures on adjacent houses and closer proximity to arterial roads with higher frequency traffic.

Biochar-red clay composites for energy efficiency as eco-friendly building materials: Thermal and mechanical performance

Biochar and red clay were used to develop eco-friendly building materials with improved thermal and mechanical performance. Rice husk, coconut shell, and bamboo were prepared by thermally decomposing as biochar. Thermal conductivity measurements, scanning electron microscopy imaging, compressive strength measurements, and an infrared heat transfer experiment were performed, and the results showed that the mixture of biochar tends to lower the thermal conductivity. The compressive strength of specimens mixed with rice husk decreased, but that of specimens mixed with coconut shell and bamboo tended to increase. The infrared heat transfer test showed that the thermal performance of the mixed rice husk specimens was significant, while the specimen mixed with coconut shell and bamboo showed thermal performance improvement. A comprehensive evaluation of the improvement in thermal performance and strength indicated that a 10 wt.% mixture of bamboo was the most effective. Therefore, it was possible to effectively determine the type and weight ratio of biochar to red clay binder an important step in the study of biochar and red clay building materials.

Marine bisindole alkaloid 2,2-bis(6-bromo-3-indolyl)ethylamine to control and prevent fungal growth on building material: a potential antifungal agent

The potential antifungal activity of the marine alkaloid 2,2-bis(6-bromo-3-indolyl)ethylamine (URB 1204) was firstly assessed by minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) against different fungi. Then, URB 1204 was applied to a building material experimentally contaminated with selected fungi, in single and mixed species, for determining its potential application in preventing fungal growth. In addition, the over-time protection efficacy of URB 1204 was verified, subjecting the treated building surfaces to natural fungal contamination for 6 weeks. URB 1204 showed different antifungal activity, with the lowest MIC value (16 μg/mL) observed against Aspergillus flavus IDRA01, Cladosporium cladosporioides ATCC 16022 and Mucor circinelloides EHS03, and the highest MIC (128 μg/mL) against the dermatophytes strains. The growth Alternaria alternata BC01, Penicillium citrinum LS1, and C. cladosporioides ATCC 16022 on building material treated with URB 1204 water solution (64 μg/mL) was remarkably reduced with an effect time-dependent and related to the examined fungi. In terms of over-time efficacy, the samples treated with URB 1204 showed a delay of fungal growth comparable with that of a commercial antifungal product. These findings evidenced not only the ability of 2,2-bis(6-bromo-3-indolyl)ethylamine to limit the growth of different fungal species on building material but also to provide long-term protection against mold growth and proliferation, opening new perspectives for URB 1204 as preventive agent.

Hens can ingest extruded polystyrene in rearing buildings and lay eggs contaminated with hexabromocyclododecane

The overall concentration of hexabromocyclododecane (HBCDD) in eggs is low although abnormally high concentrations exceeding 3000 ng g^-1 lw have been reported. In order to test whether these contaminations may originate from the ingestion of insulating materials in rearing buildings, a group of 55 hens raised in a collective cage was provided with a 64-g piece of extruded polystyrene (XPS, 2.59% HBCDD of which 75, 15 and 10% as α-, β- and γ-HBCDD, respectively). Hens entirely consumed the piece within 3 days, leading to a mean daily exposure of 4.7 mg HBCDD per kg body weight. Whole egg HBCDD concentration reached a maximum of 1037 ng HBCDD g^-1 fresh weight (fw), recorded 2 days after the piece had disappeared, and decreased down to 86 ng g^-1 fw within the 19 following days. In all these samples, HBCDD was made of 98.7 ± 0.7 and 1.3 ± 0.6% α- and β-HBCDD, respectively, and 0.1% γ-HBCDD when quantified; it was enriched in (-)α- and (+)β-HBCDD with enantiomeric fractions of 0.438 ± 0.009 and 0.579 ± 0.030, respectively. HBCDD was quantified in all the individual eggs collected the last day of experiment at concentrations ranging between 0.47 and 1361 ng g^-1 fw, according to a lognormal distribution. The ingestion of XPS in degraded rearing buildings is thus a plausible cause of on-farm egg contamination by HBCDD which should be strictly avoided.

Validation and uncertainty estimation of UPLC-PDA method for the analysis of polycyclic aromatic hydrocarbons in concrete

Human exposure to persistent organic contaminants, from building materials, negatively affects people's health and overall quality of life. This paper presents the validation and uncertainty assessment of the analytical method, developed for the simultaneous determination of 16 EPA polycyclic aromatic hydrocarbons (PAHs) in solid-solid concrete by ultra-performance liquid chromatography with photo diode-array detector. Linearity of calibration curves was good over the whole range of calibration. Limits of detection varied between 0.2 and 2.9μgkg^-1. The accuracy in terms of recovery of the validated method is within the range from 54 to 106%. The developed method proved to be appropriate for analysis of PAHs and can be used for the quality control testing of concrete during the construction of new buildings, the old residences and related buildings associated with sick-building syndrome. In addition, this is the first reported method described for the evaluation of PAHs in solid-solid concrete.

Radon exhalation study of manganese clay residue and usability in brick production

The reuse of by-products and residue streams is an important topic due to environmental and financial aspects. Manganese clay is a residue of manganese ore processing and is generated in huge amounts. This residue may contain some radionuclides with elevated concentrations. In this study, the radon emanation features and the massic exhalation rate of the heat-treated manganese clay were determined with regard to brick production. From the manganese mud depository, 20 samples were collected and after homogenization radon exhalation characteristics were determined as a function of firing temperatures from 100 to 750 °C. The major naturally occurring radionuclides ⁴⁰K, ²²⁶Ra and ²³²Th concentrations were 607 ± 34, 52 ± 6 and 40 ± 5 Bq kg^-1, respectively, comparable with normal clay samples. Similar to our previous studies a strong correlation was found between the internal structure and the radon emanation. The radon emanation coefficient decreased by ∼96% from 0.23 at 100 °C to 0.01 at 750 °C. The massic radon exhalation rate of samples fired at 750 °C reduced by 3% compared to samples fired at 100 °C. In light of the results, reusing of manganese clay as a brick additive is possible without any constraints.

Toward a holistic environmental impact assessment of marble quarrying and processing: proposal of a novel easy-to-use IPAT-based method

Marble is a natural dimension stone that is widely used in building due to its resistance and esthetic qualities. Unfortunately, some concerns have arisen regarding its production process because quarrying and processing activities demand significant amounts of energy and greatly affect the environment. Further, performing an environmental analysis of a production process such as that of marble requires the consideration of many environmental aspects (e.g., noise, vibrations, dust and waste production, energy consumption). Unfortunately, the current impact accounting tools do not seem to be capable of considering all of the major aspects of the (marble) production process that may affect the environment and thus cannot provide a comprehensive and concise assessment of all environmental aspects associated with the marble production process. Therefore, innovative, easy, and reliable methods for evaluating its environmental impact are necessary, and they must be accessible for the non-technician. The present study intends to provide a contribution in this sense by proposing a reliable and easy-to-use evaluation method to assess the significance of the environmental impacts associated with the marble production process. In addition, an application of the method to an actual marble-producing company is presented to demonstrate its practicability. Because of its relative ease of use, the method presented here can also be used as a "self-assessment" tool for pursuing a virtuous environmental policy because it enables company owners to easily identify the segments of their production chain that most require environmental enhancement.

Screening for halogenated flame retardants in European consumer products, building materials and wastes

To fulfill national and international fire safety standards, flame retardants (FRs) are being added to a wide range of consumer products and building materials consisting of flammable materials like plastic, wood and textiles. While the FR composition of some products and materials has been identified in recent years, the limited global coverage of the data and the large diversity in consumer products necessitates more information for an overall picture of the FR composition in common products/materials. To address this issue, 137 individual samples of various consumer products, building materials and wastes were collected. To identify and characterize potential sources of FRs in indoor environment, all samples were analyzed for content of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs) and novel flame retardants (NFRs). The most frequently detected were HBCDDs (85%), with the highest median concentration of Σ₄HBCDDs of 300 mg kg^-1 in polystyrenes. The highest median concentration of Σ₁₀PBDEs was found in recycled plastic materials, reaching 4 mg kg^-1. The lowest concentrations were observed for NFRs, where the median of Σ₁₂NFRs reached 0.4 mg kg^-1 in the group of electrical & electronic equipment wastes. This suggests that for consumer products and building materials that are currently in-use, legacy compounds still contribute to the overall burden of FRs. Additionally, contrasting patterns of FR composition in recycled and virgin plastics, revealed using principle component analysis (PCA), suggest that legacy flame retardants are reentering the market through recycled products, perpetuating the potential for emissions to indoor environments and thus for human exposure.

Direct determination of radionuclides in building materials with self-absorption correction for the 63 and 186 keV γ-energy lines

The use of 911 keV and 129 keV γ-line intensity ratio has been applied for self-absorption correction of the 63 keV (234)Th ((238)U) and 186 keV((226)Ra and (235)U) lines in typical building materials and soil samples. Proposed procedure allows to determine (238)U from the (234)Th line (63 keV) and (226)Ra after subtraction of (235)U interference in the 186 keV. It is important in the case of low uranium concentration and weak intensity of (235)U 143 keV γ energy line, when activity of this radionuclide can be apprised on the natural constant (238)U/(235)U ratio, only (excluding accidental anthropogenic depleted uranium deposition in the soil samples). Therefore, by this method a direct and fast determination of the (226)Ra and other important radionuclides, without one month waiting period for (226)Ra-(222)Rn daughter equilibrium, is possible. The accuracy of the method has been confirmed (relative relation deviation <10%) for typical buildings materials such as: tales, bricks, concrete blocks and various type of ceramic materials.

Radiological health assessment of natural radioactivity in the vicinity of Obajana cement factory, North Central Nigeria

Measurements of activity concentrations of natural radionuclides in and around Obajana cement factory, North Central Nigeria have been carried out in this study to determine the activity levels of natural radionuclides in different environmental matrices in order to assess the radiological health hazards associated with the use of these matrices by the local population. A low-background Pb-shielded gamma spectroscopic counting assembly utilizing NaI (Tl) detector was employed for the measurements. The results show that sediment samples have the highest activity concentrations of all the radionuclides relative to soil, farmland soil, and rock samples. The radium equivalent activity and indoor gamma dose rates together with the corresponding annual effective indoor doses evaluated were found to be lower than their permissible limits. It suffices to say, that contrary to age-long fear of radiation risks to the population in the vicinity of the cement factory, no excessive radiological health hazards either indoors and/or outdoors is envisaged. Therefore, the environmental matrices around the factory could be used without any restrictions.

Formaldehyde emission behavior of building materials: on-site measurements and modeling approach to predict indoor air pollution

The purpose of this paper was to investigate formaldehyde emission behavior of building materials from on-site measurements of air phase concentration at material surface used as input data of a box model to estimate the indoor air pollution of a newly built classroom. The relevance of this approach was explored using CFD modeling. In this box model, the contribution of building materials to indoor air pollution was estimated with two parameters: the convective mass transfer coefficient in the material/air boundary layer and the on-site measurements of gas phase concentration at material surfaces. An experimental method based on an emission test chamber was developed to quantify this convective mass transfer coefficient. The on-site measurement of gas phase concentration at material surface was measured by coupling a home-made sampler to SPME. First results had shown an accurate estimation of indoor formaldehyde concentration in this classroom by using a simple box model.

Washoff of cypermethrin residues from slabs of external building material surfaces using simulated rainfall

The use of pesticides by homeowners or pest-control operators in urban settings is common, yet contributions of washoff from these materials are not easily understood. In the present study, cypermethrin, formulated as Cynoff EC (emulsifiable concentrate) and Cynoff WP (wettable powder) insecticides, was applied at typical rates to 10 different building material surfaces to examine its washoff potential from each surface. Using an indoor rainfall simulator, a 1-h rainfall event was generated and washoff samples were collected from 3 replicates of each surface type. Washoff was analyzed for cypermethrin using gas chromatography-negative chemical ionization mass spectrometry. An analysis of variance for a split-plot design was performed. Many building materials had similar water runoff masses, but asphalt resulted in significantly reduced average water runoff masses (73% less). The Cynoff WP formulation generally produced greater cypermethrin washoff than the Cynoff EC formulation. In addition, results for both the WP and EC formulations indicated that smoother surfaces such as vinyl and aluminum siding had higher washoff (1.0-14.1% mean percentage of applied mass). Cypermethrin washoff from rough absorptive surfaces like concrete and stucco was lower and ranged from 0.1 to 1.3% and from 0 to 0.2%, respectively, mean percentage of applied mass. Both building material surface and formulation play a significant role in cypermethrin washoff.

A systematic review of radon investigations related to public exposure in iran

Background

The main sources of radiation exposure of all living organisms including humans are natural. In fact, radon and its decay products are the cause of 50% of the total dose that is derived from natural sources. Because of the significant health hazards of radon gas, its levels are widely monitored throughout the world. Accordingly, considerable researches have also been carried out in Iran.

Objectives

The aim of this research is a systematic review of the most recent studies associated with evaluation of radon gas levels in Iran. The main emphasis of this study was on public exposure to radon gas.

Materials and Methods

The most important route of exposure to such radiation is indoor places. In this investigation measurement of radon in water resources, tap water, indoor places and exhalation of radon from building material, the major sources of indoor radon gas emission, were considered.

Results

Significantly high levels of radon gas were found mostly in water and residenvial buildings.

Conclusions

It conclusion with regard to the study of building materials, granite stone and adobe coverings cannot be recommended for construction purposes.

A rapid and accurate method, ventilated chamber C-history method, of measuring the emission characteristic parameters of formaldehyde/VOCs in building materials

The indoor pollution caused by formaldehyde and volatile organic compounds (VOCs) emitted from building materials poses an adverse effect on people's health. It is necessary to understand and control the behaviors of the emission sources. Based on detailed mass transfer analysis on the emission process in a ventilated chamber, this paper proposes a novel method of measuring the three emission characteristic parameters, i.e., the initial emittable concentration, the diffusion coefficient and the partition coefficient. A linear correlation between the logarithm of dimensionless concentration and time is derived. The three parameters can then be calculated from the intercept and slope of the correlation. Compared with the closed chamber C-history method, the test is performed under ventilated condition thus some commonly-used measurement instruments (e.g., GC/MS, HPLC) can be applied. While compared with other methods, the present method can rapidly and accurately measure the three parameters, with experimental time less than 12h and R(2) ranging from 0.96 to 0.99 for the cases studied. Independent experiment was carried out to validate the developed method, and good agreement was observed between the simulations based on the determined parameters and experiments. The present method should prove useful for quick characterization of formaldehyde/VOC emissions from indoor materials.

Determination of radon exhalation from construction materials using VOC emission test chambers

The inhalation of (222) Rn (radon) decay products is one of the most important reasons for lung cancer after smoking. Stony building materials are an important source of indoor radon. This article describes the determination of the exhalation rate of stony construction materials by the use of commercially available measuring devices in combination with VOC emission test chambers. Five materials - two types of clay brick, clinker brick, light-weight concrete brick, and honeycomb brick - generally used for wall constructions were used for the experiments. Their contribution to real room concentrations was estimated by applying room model parameters given in ISO 16000-9, RP 112, and AgBB. This knowledge can be relevant, if for instance indoor radon concentration is limited by law. The test set-up used here is well suited for application in test laboratories dealing with VOC emission testing.