A NEW APPROACH FOR THE DETERMINATION OF MSD OF ASPHALT CEMENT USING HPGPC

ABSTRACT

A comparison between spectrophotometry and gravim-etry to study MSD of asphalt is presented. Spectrophotometry suffers from not detecting saturated compounds, as well as from variation of molar absorptivity during analysis. To address this, an asphalt sample is fractionated, and the relative molar absorptivity determined for each fraction. Using another sample weight of the whole asphalt, the saturates are separated, and injected to get their MSD using refractive index detection. This information - when used to mathematically treat the whole asphalt distribution data - can correct the latter to include saturates as well, but can only partially account for continuous variation of the molar absorptivity.

Gravimetry is not susceptible to the above, or other, limitations. The accuracy, comparing weight injected with that collected, equals ±0.56 mg, and the maximum difference between double analyses is 1.4%

Two identical, UV-detected MSD profiles did exhibit distinctly different MSD data using gravimetry