Cláudio Henrique Soares Del Menezzi

Utilization of the coconut shell of babaçu (Orbignya sp.) to produce cement-bonded particleboard.

This experiment evaluated the use of the material of the outer coconut shell of babaçu (Orbignya sp.), a palm tree from Brazil, for the manufacture of particleboards bonded with Portland cement. Four treatments were analyzed at two target densities (1.2 g/cm3 and 1.4 g/cm3) and two levels (0% and 4%) of addition of calcium chloride. The lignocellulosic material from babaçu presented a low cement inhibition index according to the hydration test. Testing of manufactured panels showed that good physical and mechanical properties were achieved at the treatment levels tested.

Produção de painéis de madeira aglomerada de Grevillea robusta A. Cunn. ex R. Br.

The objective of this study was to evaluate the feasibility of the use of Grevillea robusta for particleboard manufacturing. The boards were manufactured in the densities of 0,60 and 0,80 g/cm³ and resin contents of 6 and 8%. The results of physical and mechanical properties of the boards manufactured with 0,80 g/cm³ density and 6% resin content, showed that Grevillea robusta wood may be used as alternative raw material for particleboard manufacturing.

Compatibility of Pretreated Coir Fibres (Cocos nucifera L.) with Portland Cement to Produce Mineral Composites

The objectives of the present work were to evaluate the chemical compatibility between coir (Cocos nucifera L.) and cement and to study treatment methods to improve this compatibility. In the inhibition test, cement hydration temperature evolution was measured in the absence and presence of untreated and treated coir fibres (cold water, hot water and NaOH), besides the addition of 4% of CaCl2. The chemical characterization of untreated and treated coir fibres was done by determining the content of extractives, lignin, and holocellulose. The inhibition test graded the untreated fibre as “extreme inhibition,” ratifying the need to provide it a treatment. Treatments done on coir fibres affected positively the compatibility between cement and fibre, reducing the inhibition. The treatments reduced the lignin coir fibres’ and extractives proportion, whose variation was significantly correlated with the reduction of the inhibitory index. These results indicate a possibility for future incorporation of these fibres into the production of mineral composites.

EFFECT OF WOOD DENSITY AND SCREW LENGTH ON THE WITHDRAWAL RESISTANCE OF TROPICAL WOOD

In most timber connections a metallic pin is required due to lateral forces, but occasionally selftapping screws are required due to tensile stresses. The aim of this study was to experimentally determine the withdrawal resistance of self-tapping screws in tropical wood species by analyzing the influence of wood density and screw penetration length. For this, withdrawal resistance tests using hex lag screws of 12.7 mm diameter and different thread lengths were performed in specimens of the following species: Angelim (Dinizia excelsa), Freijó (Cordia goeldiana), Ipê (Tabebuia sp.), Louro-vermelho (Nectandra rubra), and Marupá (Simarouba amara). It was verified that the maximum load of screw withdrawal increases with increasing screw length inserted in wood and wood density. However, screw rupture may occur in denser species because the withdrawal load exceeds the screw strength limit. Therefore, lower screw lengths are recommended for denser woods.