site.btaDay 48: Physicist and Expert on Concrete Discusses Construction Challenges in Harsh Antarctic Conditions
There are three main challenges to the construction of the concrete foundations of the new laboratory unit at the Bulgarian Antarctic base on Livingston Island, Oleg Vassilev from the Bulgarian Antarctic Institute told BTA. He is a specialist in the design of concrete compositions, a physicist and a participant in the 31st Bulgarian Antarctic expedition as a builder and logistician.
Vassilev is responsible for the construction of the foundations of the new laboratory unit at the Bulgarian St Kliment Ohridski Antarctic Base.
The single-storey building will be erected on 32 foundation steps. Fifteen of them have already been laid during the previous expedition, which leaves 17 more to be completed during this expedition.
"The Antarctic creates a complex environment for building concrete and maintaining its mechanical properties in accordance with the parameters laid out in the construction plan. "The Antarctic creates a complex environment for building concrete and preserving its mechanical performance in the way that these performance parameters are laid out in the construction plan. The main challenges arise from multiple freeze-thaw cycles, a process in which water cycles from a liquid to a solid state, expanding and causing deepening damage in the hardened concrete.
The jargon term for this process is an 'ice wedge' - a wedge that gets bigger and bigger until the concrete completely collapses," the specialist explained.
Preliminary tests were carried out in a laboratory in Sofia to determine the correct design and preparation of the concrete composition. "The results we have achieved enable us to guarantee the long-term operation of the facility," he said.
"Another aspect that makes the concrete specific to the environment in which we are placing it is the chemical erosion caused by the proximity of the sea. We use high-strength sulphate-resistant cement manufactured in Bulgaria. It is designed for this type of use," said Vassilev.
"The third challenge we face stems from the geometry of the future building, which is designed to self-clean from accumulating drifts. Constructing this type of building is a preventative measure against snow drifts. For this purpose, the building is placed on columns above the ground to ensure a high wind velocity to prevent snow drifts from accumulating. This type of construction creates a tensile load. This is precisely the reason why we look for high compression-strength values from concrete, but also tensile strength in bending," the specialist added.
The foundation steps have the same cross-section - 1m x 1m, while their height varies according to the elevation of the terrain (ed. note: the location of the new block is on Pesyakov Hill, where the terrain is uneven). There are at least 75 metres of reinforcing iron bars in each foundation step, which means that a total of about 2,400 metres of reinforcing iron are unloaded on the construction site.
Taking such measures ensures the building's long life and minimal retrofitting costs. Based on the preliminary preparations during the pre-project design, Vassilev says he can firmly say that no renovation of the foundation steps will be necessary in the next 75 years.
BTA's Daily News editor Konstantin Karagyozov is the only member of the media who is travelling on board the ship to Livingston Island and back, and will cover the Bulgarian expedition on site throughout the stay in Antarctica.
All media outlets can use the Bulgaria-Antarctica BTA's Log for free.