The effects of cracks and holes on the exhalation of radon from concrete

Man, C.K.; Yeung, H.S.

doi:10.1016/s0360-1323(96)00070-4

Cited by 10 publications

(5 citation statements)

References 2 publications

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“…Only very few studies have addressed the issue of cracks in concrete and the effect on the exhalation rate by inducing cracks into the concrete. Man & Young [2] performed a study simulating cracks by shifting the surface area of concrete blocks but with an overall identical volume of the concrete cubes. There was no evidence of any difference in the exhalation rate.…”

Section: Ionizing Radiation and Healthmentioning

confidence: 99%

Effect on Radon Exhalation Rate Due to Cracks in Concrete

Döse

Silfwerbrand

2019

Nordic Concrete Research

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The second largest cause of lung cancer in the World is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI), part of RISE (Research Institute of Sweden AB), has examined the effects of cracks in concrete on two different concrete recipes where an Ordinary Portland Cement, OPC-CEM-I concrete (REF) and an OPC concrete including a hydrophobic additive (ADD) were addressed. Two concrete prisms from each concrete recipe were examined. The radon exhalation rate was measured in the pristine state and after concrete cracks had been induced into the concrete prisms. Measurements were performed with an ATMOS 33 ionizing pulsation chamber. The results indicate a strong influence of cracks on the radon exhalation rate. An increase in radon exhalation rate was calculated for every test prism. The increase in radon exhalation rate varied between 80 and 260 %. The crack apertures may play a significant role on the exhalation rate. The concrete prisms with the largest apertures (ADD) also generated the highest radon exhalation rates. The results imply that there could be a substantial variation in the exhalation rate, due to numerous factors, but nonetheless, the results should, raise the awareness of the impact cracks in concrete structures, may have on the final exhalation rate of radon. The exhalation rate of the recipe with an additive (ADD) also showed a lower exhalation rate than for the reference recipe (REF), when compared in a pristine state. This was in part expected. However, the effect of induced cracks and its aperture, seemingly trumps the effect that an additive may play on the radon exhalation rate, when cracks are induced. The hypothesis is in part verified in view of the results of the prism for the ordinary Portland recipe (REF-prisms), were an increase of approximately 100 % would be expected due to the total surface increase. The results also indicate this. The major increase in the radon exhalation rate of the ordinary Portland recipe including an additive, implies however other factors, such as minor internal cracks, that may substantially contribute to the final exhalation rate.

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Section: Ionizing Radiation and Healthmentioning

confidence: 99%

Effect on Radon Exhalation Rate Due to Cracks in Concrete

Döse

Silfwerbrand

2019

Nordic Concrete Research

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“…Indoor radon content can be calculated as (Man and Yeung, 1997;Petropoulos et al, 2001): where C (Bq/m 3 ) is indoor radon content at steady state, E (Bq/m 2 /h) is radon exhalation rate, A (m 2 ) is radon exhalation surface (in this study, the house floor), V (m 3 ) is the volume of the house, l Rn is the radon decay constant (2.1 Â 10 À6 s À1 ) and l v (h À1 ) is the air change rate in the house. Using E ¼ 65 Bq/m 2 /h (Clavensjo and Akerblom, 1994) and data provided for the case study house, with Equation (1) gives indoor radon levels for different ventilation rates; C 0.0 ¼ 3,582, C 0.25 ¼ 106, C 0.5 ¼ 53, C 1 ¼ 22 Bq/m 3 .…”

Section: Analytical Analysismentioning

confidence: 99%

Simulation of ventilation effects on indoor radon

Akbari

Mahmoudi

Ghanbari

2013

Management of Environmental Quality: An International Journal

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Purpose -The purpose of this paper is to describe the use of computational fluid dynamics (CFD) to simulate indoor radon distribution and ventilation effects. This technique was used to predict and visualize radon content and indoor air quality in a one-family detached house in Stockholm. The effects of intake fans, exhaust fans and doors on radon concentration were investigated. Design/methodology/approach -In this study a mechanically balanced ventilation system and a continuous radon monitor (CRM) were used to measure the indoor ventilation rate and radon levels. In a numerical approach, the FLUENT CFD package was used to simulate radon entry into the building and ventilation effects. Findings -Results of the numerical study indicated that indoor pressure created by ventilation systems and infiltration through doors or windows have significant effects on indoor radon content. The location of vents was found to affect the indoor radon level and distribution. Research limitations/implications -It may be possible to improve any discrepancies found in this article by using a more refined representation of grids and certain boundary conditions, such as pressure and temperature differences between inside and outside and by considering some real situations in residential buildings and external situations. Originality/value -From the viewpoints of indoor air quality (IAQ) and energy savings, ventilation has two opposing functions; on the positive side it enhances IAQ and the establishment of thermal comfort, and on the negative side it increases energy consumption. This paper describes the search for a solution to cope with this contradiction.

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“…The radon concentration in the chamber volume V is described by the equation (Man and Yeung, 1997;Petropoulos et al, 2001):…”

Section: Radon Exhalation Ratementioning

confidence: 99%

Simulation of Radon Transport through Building Materials: Influence of the Water Content on Radon Exhalation Rate

et al. 2005

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Radon transport in porous materials is strongly influenced by the presence of water. It is also necessary to be able to numerically control the effects of this parameter. The radon concentration and radon exhalation rate have been determined by simulation in various building materials containing an increasing water content. It has been proved that the presence of water does not involve the same variations in the concentration on the surface of the medium, according to its porosity. For porous media with low porosity like concrete or granite, ( < 0:2), the radon concentration and radon exhalation rate sharply increase with water until the volumetric water content becomes higher than 30%. At this point, radon emanation plays an important role, in relation to the molecular diffusion process. For materials with medium porosities (e.g., limestone, brick, cement: 0:3 < < 0:45), the concentration was observed to increase up to a volumetric water content of about 10% and then decreased from there. In this case, the molecular diffusion has a greater effect due to a greater quantity of pores in the material. For a small water content, this parameter tends to make the radon concentration decrease at the surface of the medium. These simulations have been compared with experimental analysis and are in strong accordance with the experimental results.

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The effects of cracks and holes on the exhalation of radon from concrete

Cited by 10 publications

References 2 publications

Effect on Radon Exhalation Rate Due to Cracks in Concrete

Effect on Radon Exhalation Rate Due to Cracks in Concrete

Simulation of ventilation effects on indoor radon

Simulation of Radon Transport through Building Materials: Influence of the Water Content on Radon Exhalation Rate

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