Hybrid aspen clone wood mechanical properties

M. Zeps¹*, A. Gailis¹, J. Smilga¹, O. Miezite², L. Sisenis2 and I. Zariņa¹

¹Latvian State Forest Research Institute ʻSilava’, Rigas 111, Salaspils, LV 2169, Latvia
²Latvia University of Agriculture, Forest Faculty, Akademijas 11, LV 3001 Jelgava, Latvia
*Correspondence: martins.zeps@silava.lv

Abstract:

The hybrid aspen is believed to be a suitable alternative to the European aspen for raw material supply, but information on its wood properties and their variations among clones is lacking. Nevertheless, its fast growth is associated with a decrease of wood density and mechanical strength. The aim of the study was to assess wood mechanical properties of the hybrid aspen clones and their relationship with growth traits. The tree height and diameter at breast height (DBH), basic wood density, compressive strength, modulus of rupture (MOR), and modulus of elasticity (MOE) were measured for three sample trees from 22 hybrid aspen clones and one common aspen clone. Significant (all P < 0.001) differences of assessed wood properties and growth traits were found among the hybrid aspen clones. At the clone mean level, compressive strength ranged from 26.6 ± 1.3 to 36.7 ± 0.8 N mm^-2 and MOR and MOE were from 57.9 to 74.5 N mm^-2 and from 7338.5 to 9734.6 N mm^-2, respectively. The mean wood density was 383 ± 3.1 kg cm^-2. It correlated significantly (P < 0.001) with MOR (r = 0.66), MOE (r = 0.63), and compressive strength (r = 0.71) at the individual tree level. All mechanical properties of the wood showed non-significant (all P > 0.05) correlation with growth traits. Therefore, selection of fast-growing clones will not interfere with the mechanical quality of wood. However, the suitability for structural applications should be cautiously tested due to the clonal variations.

Key words:

basic wood density, bending strength, compressive strength, P. tremula × P. tremuloides

Preliminary Investigation into Mechanical Properties of Clay Reinforced with Natural Fibres

P. Peetsalu¹,², J. Resev², A. Ruus², A. Menind³, Jaan Kers¹, S. Sepper¹ and J. Olt³

1 Department of Materials Engineering, Tallinn University of Technology
2 Tartu College, Tallinn University of Technology
³ Institute of Technology, Estonian University of Life Sciences,
56 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: jaan.kers@ttu.ee, andres.menind@emu.ee

Abstract:

Nowadays natural materials are popular and favoured in civil engineering. At the same time it is important to use renewable and local materials which have low CO₂ production. One of these materials is clay reinforced with natural fibres. For production purpose it is necessary to find the natural fibres which have suitable properties and can be grown in large amounts. This kind of fibre is flax, which produces a strong fibre. The article focuses on flax as a reinforcing natural fibre in clay which can be used for walls and undercoat plasters. Flax is milled to fractions with different length and mixed with clay, sand and water. Dried clay mix cube’s compressive strength is measured. Finally the best fraction as for flax length and amount is suggested for future experiments to find out the best fraction of fibres for clay with good compressive strength.

Key words: