How much limestone strength can be increased
Limestone is often used in construction for cladding of buildings and structures. This material has a soft and porous structure, which explains relatively short service life.
Assistant Professor of the Department of Water Use and Environment Yelena A. Korneyeva, together with postgraduate student of Peter the Great St. Petersburg Polytechnic University Sabri Muayad Mohanad Sabri, studied how stone-hardening impregnation based on hydrosilicic acids affects limestone.
For the tests they used the product Oxal NK 100 manufactured by MC-Bauchemie (MC Bauhemi). The research results were published in Civil Engineering Journal.
“We studied limestone from the Crimea, but in St. Petersburg there are buildings in the construction of which this material of local origin was used. For example, calcareous tuff or Pudost stone for the Kazan Cathedral (named after the place where it was mined - the village of Pudost near Gatchina). Limestone comes in many forms. We considered the densest sort, the nummulitic, of natural origin,” said Yelena Korneyeva.
For research, small cubes of stone of two types were prepared: in a natural state and impregnated with a solution. After the tests, it became clear that the treatment with Oxal NK 100 solution significantly improved the main characteristics.
For example, after 35 cycles of freezing and thawing, ordinary stone began to break down. The cubes impregnated with the solution withstood 70 cycles. Their strength increased by 23%, and water absorption decreased in almost four times. This means that much less water will enter the porous stone, and corrosion and weathering will be reduced.
Builders and restorers should be able to use the results of research in their work.
Text: Angela Semicheva
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