ABSTRACT

Notched Izod impact tests were conducted on wet and dry specimens of a pultruded, glass fiber-reinforced polymer composite after thermal cycling between 25 and -50°C. Specimens were impacted following the application of 50, 150, and 300 thermal cycles. The results indicate that moisture initially had a beneficial effect on the notch toughness, probably due to a reduction in residual stresses from matrix swelling. After 300 thermal cycles, the beneficial effect of moisture was negated, likely due to an increase in damage from freeze/thaw expansion of the water, and a reduction in the overall moisture state in the composite. Further research is needed to quantify the damage accumulation during low-temperature thermal cycling.

INTRODUCTION

In the construction industry, time and money have always been two of the key issues. The race to develop products, methodologies, and/or materials that will cost less, last longer, and minimize the amount of time needed to complete a task has never been as intense as it is today. In the past 10 years, polymeric composite materials have generated considerable interest in the construction industry for some of these very reasons. It has long been known that composite materials possess unique and beneficial properties. They have high strength-to-weight ratios, are extremely stiff, are non-magnetic and non-conductive, provide good chemical resistance, and are lightweight, in the past, the biggest drawback to the use of composite materials was the cost. However, with recent advances in materials and manufacturing techniques, cost is quickly becoming a non-issue. Manufacturers are currently producing glass-reinforced composites in structural shapes that are intended to compete one-on-one with steel and wood. Graphite fiber reinforced polymers, once attainable only by the military and aerospace industries, are now being used economically to rehabilitate deteriorating infrastructure.

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