Predicting compressive creep behavior of virgin HDPE using thermal acceleration

The subject of this paper is the compressive creep behavior of viscoelastic materials, such as high-density polyethylene (HDPE), commonly used to manufacture a multitude of civil engineering products, including polymeric piling, decking, and fender elements. Accelerated methods to predict the tensile creep of polymers are already available. The time-temperature superposition (TTS) model is the basis of several available methods, and one of its derivatives, the stepped isothermal method (SIM), is the basis for an ASTM standard for tensile creep. In this paper, both TTS and SIM have been adapted to study the time- and temperature-dependent compressive creep of HDPE. Experimental test results on virgin HDPE indicate that both TTS and SIM are applicable for predicting compressive creep with some limitations. Preliminary results indicate that the tested virgin HDPE loaded in compression is expected to creep by approximately 2% in 100 years when loaded to an ultimate stress of 2.8 MPa (400 psi) at room temperature (24°C).