Use of Environmental SEM to Study Asphalt-Water Interactions

The environmental scanning electron microscope (ESEM) has been used to study water stripping and water penetration in asphalts. ESEM images of an asphalt-coated aggregate showed progressive cracking, flaking, and stripping of asphalt from an aggregate surface as a result of progressive freeze-thaw cycles. ESEM images of an oxidatively aged asphalt that was stored underwater for six and 27 weeks showed evidence of increased water penetration with soak time. The results, although preliminary, demonstrate the feasibility of using the ESEM to study the effects of moisture on asphalts.