RWTH Aachen University
The 48th Construction Materials Conference
At the end of October of 2014, the Institute far Construction Research (ibac) at the University of Technology, in Aachen, Germany (RWTH) conducted the 48th Construction Materials Conference at the University Congress Center with the theme "Building conservation and building chemistry - from theory to application'.
Prof. Dr. rer. nat. Dietmar Stephan from the Department of Construction Materials and Construction Chemicals of TU Berlin presented the results of a current validation of the photocatalytic effects for reducing nitrogen oxides with titanium oxides. For this, the streets in the industrial zone in Kassel- Sanderhäuser were sealed with catalytically effective concrete paving blocks. In the course of the investiga6on it was found that a relevant factor in the decomposition of the pollutants is their retention time near the ground, in particular directly above the catalytically effective concrete block surface. Large and interconnected areas therefore favour this cleansing effect. A street grid with open surfaces is for a photocatalysis above road decks as detrimental as wind. In fact, on the over-all area, a Nox reduction of 4 % could be determined.
Precast parts for the Emscher sewage canal
The closing lecture was given by Dipl.-Ing Reinhard Ketteler of the Emschergenossenschaft, Germany's first water management association. He explained that the Emscher had already been piped a long time ago, under the German Emperor Wilhelm II, in order to provide the at the time immensely growing Ruhr region with an effective sewage system. The new sewer construction is a gigantic infrastructure measure with an estimated cost of 1.1 million euros, which is scheduled for completion by the year 2020. Interesting is that the new sewer is driven with tunnel boring machines up to a depth of up to 40 m. The collector, provided approximately every 1,200 m with partly monumental shaft structures, has a diameter of between DN 1600 and DN 2800. At the BA 30 construction section near the city of Dortmund, the sewer pipes are installed using the pipe jacking method. For this purpose, jacking equipment is hydraulically pushed from the launch pit into the ground. Next follow the sewer pipes, one by one. A gigantic press then jacks the precast concrete cylinders with a weight of up to 40 t through the ground to the reception pit. In view of the immense contract volume, the construction contractor Wayss + Freytag bought an abandoned factory especially for the purpose of manufacturing the concrete elements. Next follows the BA 40 construction section towards the west. Here, the Emscher canal is constructed by mean of the double-pipe construction method with a diameter of DN 2800 each, with segmental lining. The nominal width use~ here is the smallest that can b constructed with segmental lining. The segmental blocks are manufactured by the Austrian company Porr AG. In its subsidiary in Düsseldorf, 94 trough molds are used for producing, 107,000 segmental lining units by the year 2018. Each segment weighs around 1 t, and are in stalled divided by six. They are made of polymer concrete to provide durable resistance to the strongly corrosive chemicals, in particular sulfuric acid.
Robert Mehl, Aachen