Feasibility of glued laminated timber beams 1 with tropical hardwoods

11 A feasibility study of glulam was carried out in French Guiana using local wood species. The aim 12 was to determine gluing parameters affording satisfactory behaviour to manufactured glulam in 13 a tropical climate. 14 Three abundant wood species, with special properties, were selected for the study and 15 Resorcinol-Phenol-Formaldehyde resin was used for bonding. Three industrial parameters were 16 considered: adhesive spread rate, closed assembly time and gluing pressure. Delamination and 17 shearing tests were carried outin accordance with European Standards. 18 The tests revealed the influence of wood properties and manufacturing parameters on joint 19 resistance. In fact, the results showed that specific gravity and the shrinkage coefficientgreatly 20 influenced the gluing step. Indeed, wood with a medium specific gravity needed more adhesive 21 and more pressure than wood with a high specific gravity. In addition, planning and lamella 22 thicknesswere found to affect glue joint resistance. 1 Introduction 1 Nowadays, glued laminated timber is acknowledgedto be a high-performance 2 composite material used in construction. Indeed, this wood product enjoys high 3 mechanical properties, compared to solid wood (Guitard 1994). It is also an 4 economical and ecological material, comparing to concrete or steel, using a 5 renewable resource provided by a sustainable forest management. Despite 6 increasing glulam imports into French Guiana, these wood products need to meet 7 some specific requirements for use in a tropical climate. However, some local 8 wood species from the Amazon forest could be used for glulam manufacturing, 9 avoiding risks of degradation due to the abundance of fungi and termites. The assembling of wood products by gluing depends on many interlinked factors 11 to achieve a single glued assembly. While glulam manufacturing in temperate 12 countries has been mastered, the adhesive bonding of wood components in a 13 tropical climate raises numerous problems. One of the main problems is high 14 temperatures and humidity, which weaken the adhesive and its adhesion (EN 301 15 2006). Consequently, the gluing process is a critical step that can greatly affect 16 adhesion and the mechanical properties of glulam beams manufactured in French 17 Guiana. This step can be defined by various industrial parameters: glue basis 18 weight which is related to the glue spread rate, assembly time which indicates 19 glue polymerization status and the pressure applied to hold lamellae together 20 (Elbez and Bentz 1991). Moreover, tropical hardwood properties, such as …