School of Agriculture, Food and Ecosystem Sciences

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A study of the creep performance of microwave-modified radiata pine in different external environments

Dang, Lam Dien ( 2007)

A new innovative timber treatment developed at the CRC Wood Innovations, which involves high intensity microwave application and resins impregnation, is intended to provide products for a range of applications including structural engineering members. This study has been undertaken to obtain experimental data and provide better understanding of the creep performance and long-term behaviour of the new products. In the experiment, fifteen samples, five untreated, five treated with MUF resin and five treated with Isocyanate resin were loaded in four-point bending at 30 percent of the matched samples' failing stress, in a protected external environment in Brisbane, Australia for a period of nine months to date. The treated samples were found to produce lower relative creep deformations than the untreated sample. The samples treated with MUF resin showed better creep resistance than the samples treated with Isocyanate resin. Data from the first 90 days were used to obtain parameters for the two chosen models: the power law model and the 5- parameter model. While both models provided good fitting for the data, the 5-element model was found to possess better extrapolation capacity beyond the regression period. An increase in the period of regression data from 90 days to 150 days significantly lowered the errors in both of the models.