The biodegradable solvents cost more and aren't as effective as trichloroethane. The ignition method of asphalt content determination basically involves burning off the bituminous binder in an ignition furnace, leaving behind the aggregate. This seems very satisfactory. It produces a clean aggregate sample for gradation analysis. The results are accurate, and the accuracy of the furnace doesn't depend on aggregate type or asphalt content.
Calibrations are also transferable from one furnace to another.
The ignition furnace can be used with an internal weighing system, which is a safer alternative than using an ashing furnace where the hot samples would have to be handled. It also eliminates errors which may be introduced due to the change in weight as samples cool. The method involves burning the asphalt from a sample mix until only the aggrega te is left. Thermolyne Ignition Furnace. See the below for a discussion of furnaces.