The Madsen Road Pug

摘要

Given the technology available at that time, there were two ways of mechanizing an asphalt paving project in the early 1930s: mixing it at a batch plant and placing it with a grader or form-riding spreader; or road mix, in which aggregates and hot oil were blended together on the roadbed by repeated passes of a grader. Blade mixing was less expensive than plant mix, but the results were uneven. Each bit of aggregate had to be coated with oil, and this was often difficult with a grader. A means of producing better quality roadmix more quickly and more economically was needed, and travelling pugmills were developed in the early 1930s.