Glass blocks from borosilicate glass

Since 2007, an elevenmeter tall oval cylindermade of 15,600 glass blocks has stood on the plaza in front of the Atocha train station in memory of the victims of the terror attacks of March 11, 2004, in Madrid. The monument consists of two parts: the glass cylinder and an underground presentation room, which are connected via a round window. Inside, the names of the 191 victims and sympathy messages are engraved in a transparent plastic film. The inscriptions are illuminated at sunrise and sundown by incident sunlight on the structure, due to the transparency and lighting power of the glass. SCHOTT supplied the glass components for the cylinder, and this was a unique challenge: The blocks of borosilicate glass had to be produced in rounded form so that they could be glued together to form circular rows of blocks. Borosilicate glass is also ideal because of its high resistance to temperature changes. This is important because the material must be able to withstand the large weather fluctuations at the Spanish capital. For the roof construction, SCHOTT supplied flat 10 and 12mm thick floated borosilicate flat glass andmounting brackets,which had to be thermally tempered to increase their mechanical strength.