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The effect of temperature on the performance of glass-fiber-reinforced high-density polyethylene composite railroad crossties

The effect of temperature on structural materials is a major concern in engineering applications. Thermoplastic composites are highly sensitive to temperature changes and recycled high-density polyethylene (HDPE) is no different in that respect. Temperature variations may alter the mechanical properties for even the best designed HDPE compositions. Thermoplastic materials usually experience a lower modulus of elasticity and higher ductility at elevated temperatures and a higher modulus of elasticity and lower ductility at low temperatures. Therefore, it is of vital importance to study and fully understand the nature and extent of this effect. This knowledge will enable the safe implementation of these materials in structural applications where low or elevated temperature exposure is expected. In this paper, an experimental testing program that aims to assess the effect of temperature variation on the performance of HDPE composite railroad crosstie is presented. It employs an AREMA-recommended flexural testing method for crossties; center bending, to investigate a practical operating temperature range; from 10 °F (−12.22 ℃) to 125 °F (51.67 ℃). The effect of the temperature variation has been studied for several vital performance criteria: initial modulus; modulus of elasticity; secant modulus; ultimate strain; and modulus of rupture. Finally, the development and calibration of temperature-scaling models capable of predicting these vital parameters at an arbitrary exposure temperature within the investigated range is also presented. The HDPE composite crossties exhibited favorable qualities and predictable performance variation due to temperature changes. Moreover, optimization strategies are recommended to limit and control the effect of temperature on the HDPE crossties.