Moisture absorption characteristics of epoxy based adhesive reinforced with CTBN and ceramic particles for bonded-in timber connection: Fickian or non-fickian behaviour

For in-situ bonding of pultruded rod into timber structural members, such as in the construction of bonded-in timber connection, strengthening and repair of timber structures, the adhesive used must be thixotropic, room temperature cure, environmentally stable and friendly and applied at without pressure. This study investigates the moisture absorption characteristics of three adhesives specially formulated for bonded-in timber connections where the adhesives are reinforced with nano- and micro-particles denoted as CB10TSS (standard adhesive), Albipox (CB10TSS/CTBN) and Timberset (ceramics filled adhesive) with the aim to improve mechanical properties and raise glass transition temperature. The effect of high temperatures and high humidity on the properties of adhesives were determined following conditioning at different temperatures (20C, 30C and 50C) and relative humidities (65%, 75% and 95%) and soaking in water at 20C In all cases the properties of Albipox were least affected by environment but Timberset exhibited the lowest moisture uptake. Exposure to humid environments at temperatures 20C and 30C for CB10TSS and Albipox and 50C for Timberset resulted in water uptake characterized as Fickian which had only a modest effect on properties. However, exposure to humid environments at temperature (50C) which is higher than Tg resulted in non-Fickian uptake of water for CB10TSS and Albipox and a more adverse effect on properties.