Deer Valley Airport, Phoenix | Wikimedia Commons
The project was documented by Russell Howard Schnormeier, who was an engineer with the City of Phoenix, in a 1986 paper published in Transportation Research Record , and described how the airport’s subgrade contained swelling material that was capable of going through volume changes of 8% as moisture levels varied. The report discusses the maintenance reduction after the application of the two methods, but it does not establish that the rubber membrane alone accounted for the entire 90% decline, as both designs were part of the airport’s approach to managing the underlying soil. A later Phoenix pavement study that was published in 1991 reviewed pavement applications that dated back to the 1960s and described the use of rubberized seals to limit cracking and extend pavement service life.
Because of changes in moisture content, with an 11-year assessment finding that maintenance had fallen by 90% after the new designs were introduced, while the runway that incorporated an asphalt-rubber membrane also recorded lower construction costs for materials, phoenix built two parallel runways at Deer Valley Airport in 1974 and used different pavement designs to deal with a problem of soil expansion and contraction. The Deer Valley project provided an extended field comparison of two runway designs that were built on swelling soil, and its reported results included stable subgrade moisture readings, lower material costs for the asphalt-rubber design, and a substantial reduction in maintenance after the new methods were introduced.
The authors also noted that performance varied according to pavement condition, construction details and traffic. The city tested two designs to control those changes by keeping moisture conditions in the soil beneath relatively stable. The comparison gave engineers an opportunity to examine how different pavement structures performed under similar conditions, and rather than relying only on surface appearance, the study recorded moisture conditions in the subgrade and compared the designs’ construction costs and maintenance requirements.
