Field Testing of Concrete External Layer of Curtain in Poznan Large Panel System after 30 Years of Environmental Influences

Jozef Jasiczak, and Krzysztof Girus 

Poznan University of Technology, Poland 

Abstract: A large number of residential buildings in prefabricated large-panel technology were built in Poland and Europe in the 60-90s of the XXth century. It is a common claim that these objects, in the coming years, will have to be demolished due to their bad technical condition. However, a scope of that venture exceeds economic possibilities and creates significant environmental costs thus forcing us to look for other solutions. 

  The long-term and direct impact of the external environment on the outer layer of curtain walls is significant for the durability of large-panel buildings. The authors of this article decided to conduct field testing of 30 years old concrete external layer of walls in prefabricated technological Poznan Large Panel System on the aspect of theirs durability. 

  In 2016, the survey of cracks and a series of other tests of large-panel façade, residential building constructed in 1986 in Poland was executed. Several hundred large-size, triple-layer curtain-wall slabs were surveyed. Significant damages and defects of external layer were found. Other significant deviations in thicknesses of particular wall layers were proven. 

  At the second stage, many tests, both non-destructive and destructive, were conducted. They involved determining mechanical properties of an external layer. The concrete hardness was measured using with a type N Schmidt sclerometer and core samples were taken from this layer in order to mark concrete’s compressive strength. The range of carbonation (by phenolphthalein method) and the actual location and condition of reinforcement were estimated using a ferromagnetic device to determine the condition of the external layer. 

Key words: large-panel buildings, environment influences, carbonation, Poznan Large Panel System, durability and maintenance