Radon is a natural radioactive gas that causes cancer when it is present in the lungs. In regions with a lot of Uranium and Thorium in the soil, this Radon gas is present in higher concentrations. When accumulated in a building, a real health problem is present being the second cause of lung cancer. The situation in Europe is shown in the following picture. Everything more tha yellow deserves measures against radiation.

The American government educates its citizen how to build houses to avoid Radon accumulation like shown in this leaflet. The standard method is to use a ventilated space under the floor.

The need of this ventilated space is clear if cellular glass is not taken into account. A German paper of Keller shows how Radon diffuison is measured in building materials and gives a tabel (see hereunder) with the diffusion length for Radon. This is the length Radon diffuses before it decays with harmfull radiation. A Radon barrier should have a thickness three times this diffusion length to withstand 95% of the Radon.

It is clear that a concrete beam of 200mm thickness is on the limit and that for polymer materials the joints are uppermost important. Indeed, not using a ventilated space under these systems is a risk.

But like already mentionned in a previous post, cellular glass boards are a perfect light barrier against radon. A compact layer of cellular glass boards in bitumen is a perfect screen (100 mm cellular glass is 100 times the diffusion limit of Radon) serving also as thermal insulation and avoiding expensive radon ventilation systems. The bitumen joints are the only risk but using large GLAPOR cellular glass boards  280 x 120 cm reduces this risk for radon leaks with a factor 12  compared with 59.9 x 44.9 cm boards.

On top of that, if for passive housing these GLAPOR boards are installed on a thick layer of (implicit ventilated) GLAPOR cellular glass gravel with the RDS system, even the presence of negligible concentrations of Radon in the house is eliminated and a passive housing standard thermal insulation is installed under the floor at a very good price.

Prof. Elena Yatsenko has a chair at the Platov South-Russian State Polytechnic University (NPI) in Russia. While the universities of Aalborg, Ljubljana and St. Petersburg are recycling glass, prof. Yatsenko is converting slag into cellular glass.

I found the following publications:

• Foamed slag glass – eco-friendly insulating material based on slag waste.
• RESOURCE-CONSERVING TECHNOLOGY OF HEAT-INSULATION-DECORATIVE GLASS-COMPOSITE MATERIAL BASED ON ASH-SLAG WASTES 
• PHYSICAL-CHEMICAL PROPERTIES AND STRUCTURE OF FOAMED SLAG GLASS BASED ON THERMAL POWER PLANT WASTES
• INVESTIGATION OF THE FACTORS INFLUENCING THE PROPERTIES AND STRUCTURE OF FOAMED SLAG GLASS
• Investigation of the Raw Materials’ Composition and Ratio Influence on the Structure and Properties of the Foamed Slag Glass
• Investigation of A Porous Structure Formation Mechanism of a Foamed Slag Glass Based On the Glycerol Foaming Mixture
• Investigation of flux influence on structure of foamed slag glass with a high content of slag waste
• Foamed slag glass – unique insulating material
• Investigation of the Influence of Foaming Agents’ Type and Ratio on the Foaming and Reactionary Abilities of Foamed Slag Glass
• FOAMED GLASS BASED ON SLAG WASTES

Today, most of the recycled glass is used for the standard glass industry and a minor part, which cannot be recycled for bottles and windows is today used for cellular glass. However, reusing slag waste for cellular glass is a new step in the recycling industry. Today, slag is used in the cement industry and also slag wool can be produced for thermal insulation. But it seems that a new future, namely cellular slag is arriving. Indeed, glass powder for foaming should be at least 10 times more expensive than slag powder.