In a previous post we already reported about acoustic emission experiments on cellular glass. The experiments are described in a public scientific paper.  This paper was in the mean time 96 times cited, which is a nice result. Indeed, people found the same phenomena in the crumbling of paper, in bundles of glass fibres, in theoretical simulations and in earthquakes. The citations can be found here with GOOGLE SCHOLAR. This service is invented to satisfy the ego of scientists, also mine. Like can be observed, even in 2014 after more than 15 years, the paper is still cited and this year, an important paper was found by the system.

The paper describes tensile experiments monitored with acoustic emission on polyurethane foams. They found the following similarities:

• power law distribution for the magnitudes of the events
• Power law distribution for the time between events
• almost no dependence on the density

The second power law is not present at lower temperatures, which is unexpected. At lower temperature where the foam is brittle, I would expect even more similarities.

But the paper focuses on the fact that cellular structures fail in a different way than the base material, explaining why a seriously reduced safety factor can be used. In cellular glass, this is an important property when we think about cellular glass under buildings, under large tanks with liquid gas and the intelligent GLAPOR® solution under buildings with boards and gravel. 

For years and years, I worked on the annealing of cellular glass to avoid breakage and producing foamed glass gravel is totally the opposite. But since 15 months, I daily watch the production of gravel and the product started to become very interesting to me. Indeed, in floor insulation is vapor tightness not an issue and the much more expensive horizontal boards are not necessary. Foamed glass gravel is also a durable solution for floor insulation and a nice method to use waste glass which became difficult to reuse as bottles or flat glass. On top of that, the waste glass can be foamed with healthy foaming agents, used in any house man or wife. The product does not absorb water, is 100% ecological and healthy and has a very long life time, compared to EPS and XPS. The last property is much more important under the floor (impossible to replace) than on a roof. Many companies are producing this material, which became rather cheap due to the market competition.

GLAPOR® is the only company, who is producing gravel and boards and has developed the best of two worlds. Indeed, in the GLAPOR® solution, the gravel is enclosed between walls, built from GLAPOR® cellular glass boards. In this way, rain water, falling aside the house, can not flow into the gravel, which is protected by the boards. In this way, the system has a perfect frost protection and other advantages. A schematic drawing and picture explain the above. The GLAPOR® mantra   “Fascination by glass bubbles” is well applied in this case.

Today, the gravel is sold at about 40€/m³ and the cellular glass boards at 150€/m³, making this system really competitive with the classic EPS and XPS solutions.

Gravel between upstanding boards

Actual building site with gravel between boards