Estudo de placas cimento-madeira não prensadas produzidas com resíduo de Pinus spp: dosagem, propriedades físicas, mecânicas e de reação inicial ao fogo

Abstract

Pinus residue can be used in the production of wood-cement boards as a way to allocate industrial waste to a constructive component with good physical and mechanical properties. Wood-cement boards can be used in closing panels, ceilings and facades as an alternative to plasterboard, OSB (Oriented Strand Board), Siding and other cementitious boards. Normally, the production process of wood-cement composites requires pressing, however, studies with unpressed cementitious boards containing Pinus residue have already been carried out in order to obtain lighter components and easier production, but without considering the reaction to fire of the board. To contribute to the presented theme, the aim of this study was studied as unpressed wood-cement boards produced with Pinus spp residue in terms of dosage, physical, mechanical and initial fire reaction properties. The proposed board was obtained by mixing CP V cement, Pinus spp residue from wood sawdust, water, calcium-cloride based adherence accelerator addictive, viscosity modifying additive, in addition to kraft paper, inserted on both sides of the plate to improve flexural strength. The proportion of wood, water and additives applied in the composite were defined by the compatibility between Pinus spp and cement through compressive strength tests on cylindrical specimens and consistency in the fresh state. The boards were tested for mechanical resistance through static bending and perpendicular traction tests, while the resistance to moisture was studied by testing the board in boiling water followed by verification of perpendicular traction. Water absorption and swelling tests were also carried out. The reaction to fire was studied by thermogravimetric analysis and by the board ignitability test. The results showed that the addition of 17% of Pinus spp residue on the cement mass is considered a viable proportion for the production of unpressed board. The treatment of the residue for removal of extractives, the order of mixing the components and the moisture present in the wood when added to the mixture, proved to be important variables for obtaining the composite. The strength tests showed considerable results in terms of perpendicular tension and moisture. The flexural strength obtained did not reach the normative values, however, it can be improved with the use of paper suitable for application in sealing plates. The initial analysis of the reaction to fire, verified by thermogravimetry, showed that the cement incorporated into the wood residue delays the decomposition of the material at high temperatures. Furthermore, by the ignitability test it was concluded that the adherence of the paper to the composite is essential for the best performance of the board. Thus, this study evidenced the possibility of using wood residues in construction components, including in buildings where there is a need to control the materials used in terms of fire reaction.