Strength and sorption properties of cement-bonded composites produced from eucalyptus (Eucalyptus tereticornis SM.) veneer waste

Abstract

This study investigated the effects of wood-cement ratio, calcium chloride (<i>CaCl</i>₂) addition (0-3%) and cold water extraction on strength and sorption properties of cementbonded composites produced from eucalyptus (Eucalyptus tereticornis Sm.) veneer waste. Hammer-milled particles were characterized and used. Boards measuring 150 x 150 mm were manufactured in a low pressure system at wood/cement ratios by weight of 10:90, 20:80 and 30:70 respectively at a target density of 1000kg/m3. Physical, mechanical and sorption properties of the boards were evaluated. About 50% of the eucalyptus particles were retained on 0.85 to 2.36 mm sieve sizes. The loose bulk density ranged between 118 and 136 kg/m³ at a moisture content of 8.8 %. Water absorption by the particles at 24 hours ranged between 286.0% and 433.0%. Modulus of rupture (0.4 - 3.6 MPa), flexural toughness (0.02 - 0.15 KJ/m²), and tensile strength (0.4 - 1.2 MPa) of the boards fell within acceptable limits. In virtually all specimens, over 80% of the water absorption by immersion occurred in the first 1 hour of soaking, a reflection on the water absorption capability of the eucalyptus wood particles. Strength properties not directly measured experimentally and 24-h water absorption values were successfully predicted with existing model equations. Addition of calcium chloride significantly improved the physical and mechanical properties of the panels, while cold water extraction improved dimensional stability. Boards produced with less than 30% wood content exhibited superior strength and dimensional stability properties that can be exploited in ceiling applications where sound absorption is important.

Keywords: Eucalyptus, Veneer waste, Cement composite, Strength, dimensional stability

Journal of Applied Science, Engineering and Technology Volume9,: 42-49