DURABILIDAD NATURAL EN ÁREA CEMENTERIO DE SIETE ESPECIES DE ENCINO DEL ESTADO DE GUANAJUATO

Abstract

Natural durability was assessed and service life was determined in the sapwood of seven oak species using a graveyard test. Stakes of 19 mm (T) x 19 mm (R) x 500 mm (L) were used for this purpose. Five red oak species from Guanajuato State, Mexico, were studied: Quercus castanea, Q_ coccolobifolia, Q_ crassifolia, Q. durifolia and Q. laurina, as well as two white oak species: Q. obtusata and Q. rugosa. The assessment of the stakes was carried out at intervals of six months and the criteria for assessing the attack was based on the ASTM D 1758 standard. The failure of the stakes was only due to the attack by fungi. The average six monthly decay performance values were modelled by a mathematical equation from which severa! indicators were derived. The service life in months for each species determined by the model was 57.8 for Q. castanea, 59.2 for Q. coccolobifolia, 72.2 for Q. crassifo/ia, 56.4 for Q. durifolia 58.8 for Q. laurina, 66. 7 for Q. obtusa ta and 62.6 for Q. rugosa. A proposed durability classification allowed to classify Q. castanea, Q. coccolobifolia, Q. durifolia and Q. laurina as rnoderately durable and Q. crassifolia, Q. rugosa, and Q. obtusata as durable. Twenty six months was considered the maximum period of time to use natural timber in ground contact, since the stakes reached a moderate decay grade. lt was regarded that at this stage it is still possible to preserve the timber, thus increasing its service life.