Concrete Containing Hycrete Reduces Radon Gas Exhalation by 35%

The Swedish Cement and Concrete Research Institute released a report detailing Hycrete’s hydrophobic admixture and its effect on radon exhalation rates of concrete. The study, which spanned 22 months, showed that concrete containing Hycrete reduced radon exhalation by 35% compared to the control.

Radon Gas is the Second-Largest Cause of Lung Cancer in the World

Radon is a mono-atomic gas that is the second-largest cause of lung cancer in the world. Radon gas is released by the natural decay of minerals commonly found in soil, granite, and building materials such as concrete. The study found that the primary parameters of radon exhalation in building materials are; permeability, porosity, moisture, pressure gradient, and temperature of the material. Due to the controlled nature of the study, temperature and pressure gradient were set equal to focus on the effects of permeability, porosity, and moisture content as a transport mechanism for radon.

Alternate Strategies to Reduce Radon Exhalation

A typical strategy to reduce radon exhalation is to add fly ash to the concrete mix. As the world transitions away from the use of coal-fired electrical generation once reliable sources of fly ash are becoming harder to secure and alternative strategies need to be found.

The study aimed to find an admixture that could hinder the free transport of moisture and radon through concrete. The researchers theorized that an additive that could hinder the free transport of water from the concrete surface by clogging the pores might directly affect the radon diffusion rate within concrete. Experiments were devised to test this hypothesis and to evaluate Hycrete’s effectiveness at lowering radon diffusion in comparison to fly ash.

Hycrete Outperformed the Control Sample and the Fly Ash Mix

Three identical concrete samples were placed through a series of testing where the only difference in the mixes was the addition of Hycrete to one sample, and the substitution of Portland cement with fly ash in another. The third concrete cube was used as a control. The three cubes were cured in a water bath for one week and then stored in a conditioning room at 23°C and 50% RH (relative humidity) for 22 months. Measurements were taken using an ATMOS 33 ionizing pulsation chamber at 5 different occasions to measure the exhalation rate of radon in the three samples. Hycrete outperformed the fly ash mix by 25% and a 39% improvement over the control in moist concrete conditions with a higher RH value (77.5 %+).

Researchers Concluded the Use of Hycrete Strongly Reduces the Diffusion Length of Radon

Researchers concluded it is likely that the use of Hycrete corrosion inhibitor strongly reduces the diffusion length of radon and less radon is able to reach the surface. Using the Hycrete additive may have a substantial impact on the radon gas exhalation rate of concrete and consequently the radon gas level within a room. The results demonstrated the significance and effectiveness of an additive to reduce radon levels in building materials.

To see the complete study, please visit

For additional Testing Information, please see our testing summary:

Hycrete Hydrophobic Barriers in Concrete – Fluorescence Microscopy testing conducted by the Swedish Concrete Research Institute.
Lindsey Montgomery
Lindsey Montgomery
Lindsey has over 15 years in the AEC industry and she currently manages the business development for Hycrete’s US division focusing on education and strengthening client relations.
Lindsey Montgomery
Lindsey Montgomery

Lindsey has over 15 years in the AEC industry and she currently manages the business development for Hycrete’s US division focusing on education and strengthening client relations.

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2 Responses

  1. This raises the question as to how much exposure using concrete for building brings to the table. What interior levels are deemed harmful and marginal/concerning as well as which concrete constituents bring how much radon with them and which ones we should avoid. Is there research on this as well?

    1. Hi Rob,
      Thank you for your comment. Below is some additional information.
      The International Commission on Radiological Protection (ICRP) publishes guidance on protection from radon in homes and workplaces, and dose coefficients for use in assessments of exposure for protection purposes. ICRP Publication 126 recommends an upper reference level for exposures in homes and workplaces of 300 Bq m-3. In general, protection can be optimized using measurements of air concentrations directly, without considering radiation doses. However, dose estimates are required for workers when radon is considered as an occupational exposure (e.g. in mines), and for higher exposures in other workplaces (e.g. offices) when the reference level is exceeded persistently. ICRP Publication 137 recommends a dose coefficient of 3 mSv per mJ h m-3 (approximately 10 mSv per working level month) for most circumstances of exposure in workplaces, equivalent to 6.7 nSv per Bq h m-3 using an equilibrium factor of 0.4. Using this dose coefficient, annual exposure of workers to 300 Bq m-3 corresponds to 4 mSv. For comparison, using the same coefficient for exposures in homes, 300 Bq m-3 corresponds to 14 mSv. If circumstances of occupational exposure warrant more detailed consideration and reliable alternative data are available, site-specific doses can be assessed using methodology provided in ICRP Publication 137.

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