Establishing patterns in the formation of properties of fire-resistant biocomposites based on a hybrid binder

The process that forms the properties of fire-resistant biocomposites based on wood sawdust and a binder from a mixture of gypsum and an intumescent coating based on PVA dispersion has been investigated. The task addressed is to ensure the stability of biocomposites based on a gypsum binder to changes under operating conditions. This is important since the production of biocomposites from renewable sources for construction is relevant. It has been proven that when thermally exposed to the biocomposite samples, no ignition occurred, the maximum temperature of the flue gases was about 84°C. When using a gypsum binder, a non-combustible structure was formed on the surface of the biocomposite, which prevented the sample from igniting. For a biocomposite based on a binder from a mixture of gypsum and an intumescent coating based on PVA dispersion (hybrid binder), charring of the sample surface is characteristic, which prevents its ignition. In addition, the results of determining the process of wetting biocomposites with test liquids showed that the obtained solids belong to hydrophilic materials with high water wettability. Analysis of the results of experiments on water absorption of biocomposites reveals that the maximum mass gain of the biocomposite on gypsum binder under the influence of moisture was almost 27% and the main increase in moisture occurred in the first 5 days of exposure. The mass gain of the biocomposite samples on hybrid binder was less than 10% due to the formation of a shell on the surface of sawdust. The value of the compressive strength of biocomposites showed that the sample formed on gypsum binder is significantly fragile. However, for the biocomposite formed on hybrid binder, the ultimate strength is 1.88 MPa, which is provided by the adhesive properties of the intumescent coating. Thus, there are grounds to argue about the possibility to effectively design operationally stable biocomposites for construction