During the 1950 construction season the Research Division observed the construction of several types of seal coats, a few tack coats and a penetration macadam pavement, A report, covering mostly construction practices on these projects, was submitted to the Research Committee at the February meeting in 1951. The report is titled "Observations on Seal Coats, Tack Coats, and Penetration Macadam Construction in 1950," and dated January, 1951.

A follow-up of most of these projects is submitted here, The performance of the seals was greatly influenced by failure of the bases during the very severe winter of 1950-51. Considerable frost action in many sections of the state caused failure in the lighter designed pavements.

Because of the many variations experienced when an analysis is made of different seal materials over different type surfaces with varying subgrade conditions, it was decided to set up a project and vary the materials within the limits of a given road. Such a project, including five prominent types of bituminous seal coat materials, was placed in Washington County during 1951, The quantities were not varied and the seals were placed over a fairly uniform pavement, A report of observations during construction is submitted here.

Also, during 1951 a blade spread hot mix binder course in Nicholas County was observed. This method of application of a leveling course over a surface very irregular in both crown and grade was evaluated not only from the standpoint of improvements in the contour of the finished pavement but, also, from the standpoint of feasibility in construction procedures.

Report Date


Report Number

No. 71

Digital Object Identifier