Epoxy resin formulation
In 2005, Brisbane City Council (BCC) encountered difficulties during maintenance work on the New farm Floating Walkway structure. As part of on-going repairs to the concrete pontoons, they required a material that could simultaneously: bond well to concrete; cure quickly at room temperature; be unaffected by moist or wet environments; be readily mixable on-site; have very high flexural elongation and low flexural modulus whilst still maintaining considerable compression capacity. This combination of requirements presented a major challenge to most commercially available materials. In fact, no major resin supplier was prepared to supply any guarantee that their materials could achieve all of these requirements.
BCC approached CEEFC with the request if it was possible to develop this kind of product. CEEFC took up the challenge to develop a new type of material that could achieve all these requirements. Early work using polyurethane resins and combinations of polyurethane and epoxy resins was only partially successful. It soon became apparent that only an epoxy system would be suitable. However, nearly all epoxy resin systems available were much too rigid and brittle to achieve the high elongation requirements of BCC. After a lengthy series of trials, CEEFC was able to reduce the inherent brittleness of the epoxies through the use of toughening additives to both the resin and hardener components of the system.
One of the most attractive toughening additives trialled was based on an epoxidised linseed oil developed in CEEFC's Plant Resin Project. In the end, it was only the commercial unavailability of sufficient quantities of this material that prevented it from being chosen in the final formulation. Eventually, an equivalent rubber toughened product was chosen along with a commercial high elongation amine curing agent. Prior to use by BCC, substantial modelling and testing work was conducted, including full-scale tests of the adhesion characteristics of the material when bonding polymer concrete walers to concrete.
Brisbane City Council
CEEFC Project coordinator
Dr Francisco Cardona