The reference to Siporex woke up some old brain cells. As I recall, it was an autoclaved aerated concrete (AAC) product that had very low shrinkage, high insulation and light weight (under 80 pcf and some even floated) and high fire resistance. The materials were cement, fine sand, fly ash or silica flour, aluminum powder or another "foaming" material that were compatible with the required short term (6 hours), high pressure and high temperature(360F) curing. It is seen unreinforced as rectangular units that are wire cut into selected sizes. This was a very common building material in Europe and Russia because of the insulation and the compatibility with the construction systems.
I have seen similar products in eastern Europe (almost every plant is identical (near a power station), but none in the U.S., but the product could exist in the U.S. I did see the reinforced units across the pond. The major producers were Ytong and Hebel(sp?) and there are a couple of similar plants in the U.S. At one time, there was a plant near Chicago that made AAC materials in conjunction with a power plant.
The autoclaving process requires energy, but is totally consistent and uses 100% of the cement material in a 6 hour curing cycle and produces a product with shrinkage 1/3 of that with other concrete products.
This is just a guess, but the products question could have come from the Chicago plant and could be similar to the Ytong or Hebel products that should be able to be searched since their product lines are still made. A plant in Florida also made unreinforced AAC panels for interior and exterior walls in homes.
The 2M span sounds like it came from a typical industrial building system. - Good luck on your research of the product.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
