Adhesive systems for structural connections in timber

Pull-compression tests on glued-in metric thread rods parallel to grain in glulam and laminated veneer lumber of different timber species

“…A decrease of the total load-carrying capacity is assumed when the spacing is less than 5 times the rod diameter and the edge distance less than 2.5 times the rod diameter. The results by Broughton and Hutchinson (2001a) validate the influence of small distances between multiple rods.…”

“…The shear stress at the adhesive-timber interface is also considered in relation to the rod-embedment length. Broughton and Hutchinson (2001a) studied the influence of moisture content at the time of bonding on the pull-out strength of hardwood, but the long-term behavior has rarely been considered because of missing standardized approval procedures as well as time-consuming and expensive tests. Bainbridge et al (2000), for example, studied the fatigue performance of bonded-in rods for different types of adhesives for glulam made from timber of strength class C35.…”

Influence of Adhesive Type on the Properties of LVL Made from Paricá (Schizolobium amazonicum Huber ex. Ducke) Plantation Trees

“…For LVL that used PU as an adhesive, it presented greater elasticity (less rigidity) (Figure 4). According to Broughton and Hutchinson (2001), this elasticity is common for products that use PU as an adhesive, because it presents a less rigid bonding line, usually in the form of foam caused by a reaction between the adhesive and wood moisture, producing CO 2 . Regarding the ƒ m parameter, PF was the type of adhesive that was observed to promote a greater bending resistance, while other adhesives presented an equivalent resistance (Figure 4).…”

The Influence of Curing Temperature on Rheological Properties of Epoxy Adhesives

“…A diagram of the equipment for rheological measurements is shown in Figure 1. The geometry was plateplate, with disposable plates with a diameter of 25 mm made from steel with a nominal ultimate tensile strength of: f u = 900 -1000 N/mm 2 . All experiments were performed at a frequency of 1 Hz, a strain of 0.01, and a 0.5 mm gap between the plates.…”

“…Epoxy compounds have several advantages over other resins as adhesive agents for use in timber structures and, typically, they are suitable for service temperatures in the range -30 to +60°C. They may be formulated in a wide range of forms, application characteristics and mechanical properties when cured (Broughton and Hutchinson, 2001). …”