Mechanical characterization of timber from Spanish provenances of laricio pine according to European standards

Abstract

The Spanish grown laricio pine (pinus nigra subsp. saltzmannii) covers an area of 353,000 hectares and produces an annual figure of 310,000 m³ of roundwood. It ranks as the fourth most important Spanish conifer and its timber is frequently used in construction. The results of the mechanical characterization of laricio pine timber coming from three different Spanish regions of provenance (R. 6 “Alto Maestrazgo”, R. 7 “Sistema Ibérico Meridional” y, R.8 “Cordilleras Béticas”), carried out in accordance with the methodologies and requirements of EN 408, EN 384 and EN 338, are considered in the present study. 3612 boards, from 15 different samples ranging in size from 100×40×2500 mm to 200×70×4500 mm have been tested in accordance with EN 408. The samples represent the variety of cutting patterns, log sources, sizes and quality of the material present in the market.

The testing material was classified in accordance with the Spanish standard of visual strength grading UNE 56544, which sets two different grades, namely, ME1 and ME2. One part of the sample (681 boards) was classified by applying the German standard DIN 4074. In accordance with the results, Spanish grade ME1 can be assigned to strength class C35, and while grade ME2 is assigned to C18. The influence of the rate of growth on the mechanical properties of timber was also assessed concluding that the size of the growth ring, considered at species level, is not an adequate predictor of the mechanical quality of the material. When considering the use of this timber in structures, the high level of deformations during drying (an 11.1% average value) suggests the convenience of making use of dried timber.

Different relations between the strength and local modulus of elasticity in bending of timber and the major properties studied (E _cen, E _m,g , ρ, RW) are also considered.