SAMPLING OF THE WARSAW RAILWAY STATION, POLAND
23 July 2018 | Warsaw (Poland)
During the week of July 23rd 2018, as part of InnovaConcrete project, INES Ingenieros team conducted the sampling field campaign for the material characterization of the SrodmiescieWKD Station Pavilion. The team was supported by Błażej Ciarkowski and Adam Drozdowski, art historians from University of Lodz, who took care of arranging the permits dealing with PKP (structure stakeholder) for enabling the team work on the structure and obtaining the existing documentation of the same.
The main purpose of the material characterization is understanding the properties that define the concrete with which the structure was built as well as identifying the decay processes that are currently active or that can activate in the near future due to the material composition and environmental conditions to which is exposed to.
The first step for achieving this outcome has been to conduct a full 3D model that represents the structure geometry. Knowing the shape is essential to understand its structural behavior, drainage system and the general structure exposition to the climate conditions. This 3D model was developed based in a drone survey that took images and laser scan information in order to build a point cloud file. Such model was checked on site to ensure the geometrical definition was properly built.
Using the geometrical definition, the second step was to develop a damage mapping of the structure. This will be essential for identifying possible spots where to apply the products in a future stage but also to understand which are the problems that the structure is facing and design the sampling campaign not only to define the concrete properties but also to clarify doubts on the active decay processes.
Once the damage mapping was completed, INES team conducted a set of destructive and non-destructive tests to finalize defining the material properties and condition. Regarding destructive samples, two different samples were obtained. One of the samples was oriented to determine the concrete compressive strength, its density and porosity as well as the size and shape of the arid and the water-cement content; which required a minimum size to fulfill the laboratory tests standards. The other sample taken was much smaller as the purpose is to conduct a thin sheet test to obtain a microscopic view of the concrete composition.
Both, big and small samples were used to study the depth of carbonation, which indicates the susceptibility of presenting corrosion problems among others. This was done by applying Phenolphthalein directly on the recently cut sample.
Besides this destructive samples obtained by drilling, the team could obtain extra samples of concrete from existing fallen pieces found in thetop surface of the structure deck. These will be used to analyze if the concrete contains any sulphates or chlorides by conducting salt extraction tests and using X-Ray diffraction and scanning electron microscope techniques.
Additionally, different paint, black crust from contamination and peeling samples were collected for their analysis in laboratory.
Fallen concrete sample
Fallen concrete sample
Pink and white paint samples
Black crust and peeling samples
To support and extrapolate the results from the destructive tests, the following non-destructive tests were undertaken:
X-Scan and Pachometer measurements. These were oriented to determine the concrete cover (thickness of concrete protecting the reinforcement or structural steel from corrosion) available in the different areas as well as for detecting those locations without reinforcement to enable the drilling to be conducted.
Schmidt hammer measurements. Those locations where the drillings were done were as well tested with the Schmidt hammer to calibrate it and be able to obtain measurements of compression strength and porosity from many other locations within the structures, without the need of damaging it.
Moisture measurements. The humidity differences between the different orientations within the different surfaces was studied to determine if there is any dominant pattern that can help identifying particular susceptible areas.
Thermographic measurements. Supporting the previous analysis, the team used a thermographic camera that highlights the temperature difference of the different areas. Images were taken at first time in the morning and after heavy rain to have on one hand those areas that more likely present moisture as well as to detect the water path when it rains.
All this information now needs of clerical work and laboratory testing before reaching the material properties and condition conclusions.