Vinicius Gomes de Castro

Correlation Between Chemical Composition of Tropical Hardwoods and Wood–Cement Compatibility

The objective of this study was to evaluate the compatibility degrees among primary sawing residues of eight different hardwoods from Amazonia and Portland cement type II-Z and correlate them with their chemical composition. The compatibility degree was expressed using the Inhibitory Index and the chemical characteristics were obtained by quantitative methods of extraction and analytical pyrolysis. From the species studied, five of them were classified as low inhibitory: Eschweilera coriacea, Inga paraensis, Inga alba, Pouteria guianensis, and Byrsonima crispa. There was no significant correlation between polar or non-polar soluble extractives and cement set inhibition. However, the Swartzia recurva samples with arabinose content were directly correlated with the cement inhibition. This effect also occurs with Larix because the alkali solution of the reaction cleaves the linkage between lignin and hemicellulose/cellulose and produces higher amounts of degraded polysaccharides which are responsible for the inhibition.

Particle Sizes and Wood/Cement Ratio Effect on the Production of Vibro-compacted Composites

The aim of this study was to evaluate the influence of particle size and the wood/cement ratio on the physical and mechanical properties of vibro-compacted wood-cement composites. The effects of three different particle sizes (diameter between 1.4-2.36 mm; 2.36-4 mm; and 4-9.56 mm) and wood:cement ratios of 1:2.75, 1:2 and 1:1.5 on wood-cement composites produced with the Amazonia species Swartzia recurva Poepp. and Portland cement type II-Z were analyzed. All evaluated properties were influenced by the particle size used in the mixture; however, the wood:cement ratio only affected the final density of the composite, internal bond and water absorption properties. Composites produced with particles that pass through a 2.36 mm screen but were retained with a 1.4 mm screen showed average values of modulus of rupture and higher modulus of elasticity than composites produced with bigger particles. The use of a 1:2.75 wood:cement ratio resulted in composites with higher density and dimensional stability than composites produced with a lower amount of cement.