The smoothness and ride quality of a freeway, highway, road or city street is more important than most people realize. Why? In addition to reducing the maintenance costs and improving the fuel mileage of the trucks and cars driving on the pavement, the smooth riding or rough riding behavior of the pavement has everything to do with the number of years before it will require major repairs, or complete removal and replacement. Monitoring and measurement of the rate a pavement develops roughness is internationally recognized as the standard method for determining the remaining service life of a specific length of pavement. The federal government’s Department of Transportation (U.S. DOT), through its Federal Highway Administration (FHWA), has mandated since 1990 that the Department of Transportation of each state annually evaluate and report on the smoothness of all federally financed freeways, highways and roads within their state boundaries. The measuring system is known as the International Roughness Index (IRI). It provides feedback to the federal government on the quality of each state’s design and construction programs in building their paved road networks. It also shows which states need to improve their technology and construction procedures to deliver pavements with service life measured in decades rather than years. Cement, Fly Ash and Lime, the conventional stabilizer chemicals, have been in use since the 1950’s in attempts to improve the strength of base course and subgrade layers under highway pavements, but they are costly to apply and of limited effectiveness in controlling the primary enemy of pavement durability and smoothness, which is localized or differential settlement. According to the data that has been produced from the annual IRI field testing conducted by each state DOT and provided to FHWA, an advanced stabilization product technology is proving to be far more effective in prolonging the maintenance-free smooth-running performance of asphalt and concrete pavements. These economical concentrated liquid stabilizers, known as the EMC SQUARED® System products, are simply added to the compaction water during the standard procedures used to construct the subgrade and base course layers for asphalt and concrete pavements. This is a case of doing more with less, the essence of sustainable construction. The hyperlinks provided below report on a total of seven highway projects, including two major tollways and four sections of interstate highways located in two different states. Two of these interstate highway projects using the EMC SQUARED System stabilizer products with excellent results were FHWA Demonstration Projects:

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These two lengths of pavements were constructed over worst case soil conditions that had previously failed pavements constructed on a layer of cement treated aggregate base course materials. The EMC SQUARED System stabilization treatments of aggregate base and subgrade soils dramatically outperformed cement, lime, and geosynthetic products in reducing pavement maintenance requirements and retaining pavement smoothness. The IRI monitoring data provided by the two state transportation departments reveals the performance advantages of this newer generation stabilization technology that provides superior resiliency and all-weather support for asphalt and concrete pavements.

For IRI test results and case histories on 5 additional highway projects, click here