Beginning in 1968, Benkelman beam deflection tests were run on 25 bituminous roadways located throughout the state. Tests were run before overlay, just after these projects were overlayed, one year after, and two years after. The results were analyzed to determine the strengthening effect of the bituminous overlay.
In conjunction with this study, Benkelman beam tests were run at various short intervals on a number of randomly selected flexible pavements. These results were used to develop a testing schedule (number and location of test points required) in order to assess the deflection characteristics of a flexible pavement within a given degree of accuracy.
The main purpose of this investigation was to determine the amount of degradation that occurs during construction of granular bases and the amount which takes place while in service under a bituminous surface. A second objective was to determine which laboratory tests could be used to identify the materials which would degrade the most.
Six granular base projects were selected for testing. Six different aggregates were tested and results analyzed for degradation. Assessment of degradation was based on changes in the percent passing the No. 200 sieve of samples taken as produced, after compaction and after being placed in service.
Some of the more important findings and conclusions of this study are:
1. Some degradation was noted on all six projects, occurring both during compaction and under traffic.
2. None of the laboratory tests conducted were found to be suitable for indicating aggregates which degrade the most.
In recent years, more emphasis has been made on making street and highway corridors more aesthetically pleasing. Two areas which have sometimes proved to be a problem are the boulevard between the curb and sidewalk, and raised medians. Grasses and other natural growths are pleasing to look at, but have not proved to be satisfactory in all cases because of lack of watering and severe exposure to salt and plowed snow. Therefore, durable artificial coating materials were considered to be one solution for these areas.
The purpose of this report is to present the results of a literature search and results and comments from discussions with persons knowledgeable of these types of materials. Emphasis was placed on materials or systems which would provide a color contrast from normal asphalt or portland cement concrete pavement color and provide a three-dimensional appearance. The original intent of this report was that it be a state-of-the-art report including a list of products available, along with cost, application procedures and performance characteristics. It did not take long to determine that such a list would be endless. There are so many products on the market that it would be impractical to list them all. Therefore, to avoid any implication of partiality none will be reported, using brand or trade name.
