How did asphalt become dominant in pavement technology? This analysis argues that the victory of asphalt, as of many other technologies that compete with alternatives, is not so much the result of substitution at the level of the artifact or of the technology, but rather is the result of competition at the level of (technical) properties and (user) functions. The case of pavement technology shows that that technology becomes dominant which appears to be able to integrate as many functions as possible, and notably those originally provided by rival technologies, into its own system. This analysis concludes that in the history of technology the artifact does not always seem to be the most fruitful unit of analysis. Seen from the perspective of the user, artifacts are carriers of function sets. From the perspective of the designer or producer, the technology or artifact that contains the set of properties which best enables the preferred function set has a better chance of becoming dominant.