The results of this investigation to date indicate that the stabilometer may be a very useful tool in the evaluation of Minnesota soils and aggregates. However, the method of applying the results of the test to the design of flexible pavements still has to be established. This remaining problem is undoubtedly the most difficult and will be the third phase of Investigation No. 176
Since the initiation of Investigation No. 603 in the summer of I960, Materials and Research personnel have been conducting plate bearing and Benkelman beam tests on County Roads and Municipal Streets located throughout the state. County and Municipal Engineers have indicated their enthusiasm for this project through the numerous letters received each year submitting roads for testing. The plate bearing spring axle load data, the condition survey results, and the boring information have provided them with information related to the performance of their typical flexible pavement design and some guide lines for use in placing spring axle load restrictions.
In addition to providing performances arid load restriction data, the study was initiated to determine the relationship of the time tested plate bearing test and the more economic Benkelman beam test. This relationship has been established and a means of computing an estimated spring axle load capacity using Benkelman beam deflection data is presented in this report. However, there are certain limitations that must be considered before this method can be used with any degree of confidence. The 1964 field tests will be used to evaluate this method as well as the other relationships presented in this report.
