Konferensartikel

High voltage submarine cables and umbilicals are armored using galvanized steel wires. Polymer modified bitumen (PMB) is used to protect these wires from corrosion. During handling (spooling and bending) of cables at low temperatures the PMB will give rise to high shear forces between the armoring wires which reduce the cable’s capacity (allowed combinations of axial tension and bending curvature) and increase the fatigue damage. It is therefore of interest to investigate the relationship of the viscoelastic properties of PMB and temperature. Material testing has included characterization of PMB by a controlled stress rheometer from -15 to +30ºC. The applied frequency was in the range 0.005 Hz to 0.5 Hz. The tests were done at strain values of 0.01%, 0.1% and 1%. Different parallels were analyzed with respect to variance/precision in the data. The results indicate that high strain and high frequency greatly affect the variance at low temperatures. The average of the parallels was used for making a regression model for the complex shear modulus, G*, as a function of temperature, frequency and softening point. This paper focuses on building a model for prediction of minimum temperature and maximum frequency for cable handling with respect to the viscoelastic behavior of polymer modified bitumen.

Rheology; Bitumen; Cables; Umbilicals