CHARRING LAYER ON A CROSS-LAMINATED TIMBER PANEL CONSTRUCTION

When the wood is thermally loaded, the microscopic changes of wood structure and macroscopic changes appear and are examined. The macroscopic changes include formation of char layer on the surface of the wood-based material. The main aim of the medium-scale test is to assess the char layer formation on the surface of the sample under thermal loading. The test sample was made of CLT (cross-laminated timber) panel with no surface treatment with the dimensions of 1000 x 1500 x 80 mm. It was a 3-layer panel made of spruce lamellas. The test sample underwent a medium-scale test during which it was exposed to a radiation panel for 40 minutes. Intensity of the radiation panel was 43.1 kW.m(-2). During the test, the temperature on the exposed side of the test sample was recorded by a thermocouple. The test sample immediately began to degrade and char. After complete charring of the CLT panel layer on the exposed side, its rupture and consequent falling off appeared. The middle layer of the CLT panel was minimal, only in the area where the outer layer fell off. The results of the medium-scale test were compared to the results of the simulation which were achieved from the Ansys 18.1 program. When the medium-scale test and simulation results were compared, some differences were found. The main difference was found when the char layer fell off from the CLT panel and further charring into the depth of the sample followed in the medium-scale test.