| Abstract [eng] |
In today's world, Europe is leading the fight against climate change with the goal to become climate neutral through the European Green Deal by 2050. The construction sector, as one of the most polluting, is particularly focused on changes. Cement, being an extremely polluting material, is being out phased. 50% of the construction materials of public buildings will have to be of organic origin starting from February 2024 in Lithuania. One alternative is to replace concrete floor slabs with cross-laminated timber (CLT) panels. Since more strength is often required than CLT panels alone can provide, this floor is additionally poured with a layer of concrete, creating a composite floor that is 3 to 5 times more resistant to bending forces than CLT alone of the same thickness. Although much research has been done on joint types and shear reduction, there is a lack of knowledge on the interaction between wood and concrete in composite panels, such as how the water absorption of wood affects the physical and mechanical properties of concrete. There is also a lack of information on which wood impregnation/coating methods are rational, since water damage is an important issue in construction. After the literature review, two potent materials were selected for coating of the wood, which have a potential to solve one or more problems. The first material chosen is mineral oil and second material chosen is a two-component cement-polymer waterproofing. This study was conducted in the faculty laboratory, where the mechanical and physical properties of composite wood-concrete panels were tested with different wood coatings and the results were compared with a reference sample that was not coated with any material. The results of 14 samples were obtained after testing. 4 CLT and 3 LVL specimens were used for experiment and values were measured 3, 7, 14 and 28 days after pouring concrete. After testing the moisture content of the wood, it was found that without using any CLT coating, the wood absorbs too much water and exceeds the requirements. Mineral oil coating did not have a significant effect on the moisture absorption of the wood. High-quality waterproofing helps reduce the moisture content of CLT, and it is possible to maintain a moisture content of less than 16 percent, which in turn should solve many of the challenges builders face due to precipitation and water ingression during construction. The compressive strength of the concrete ranges from -5.4 to 7.8% compared to the sample that was not coated with anything. The interaction between wood and concrete is complex and the strength of concrete depends on the moisture content, direction and coating of the wood. During the tests, no direct correlation between wood moisture content and concrete strength was found and, perhaps, other factors such as the amount of air in the concrete, the density of the mixture and the flowability may have no less influence on the final strength of the concrete. |
