A Limestone-Calcium Chloride Stabilized Base

This report is mainly concerned with the calcium-chloride stabilized portion of a combination base. A 4-inch course of waterbound macadam was placed over a 1-inch insulation course overlying an existing traffic-bound stone surface. The next 4 inches of base above, the water bound material consisted of two 2-inch layers of calcium-chloride stabilized limestone of a design not used heretofore by the Department. Bituminous concrete binder and surface courses laid over the base brought the total mat thickness to more than 11 inches. The surface width was 30 feet, and the length of the project was 1.1 miles. Although the road is located about 2 miles south of the Lexington city limit, it serves an area which is essentially urban. In addition it is a link between U.S. 27 and U.S. 68 as shown in the sketch map of Fig. 1. The traffic volume anticipated in the near future is approximately 1500 vehicles per day of which a fairly large percentage will be commercial because of the business and industrial zone nearby and the convenience this route offers in avoiding congested streets within Lexington carrying U.S. 27 north and south. From an investigational standpoint, interest was centered on the so-called stabilized courses, not only because of the unusual stone gradation involved but also the feasibility of mixing and spreading these courses with patrol graders. This process was under observation as a means for simplifying macadam construction and improving the riding qualities of the finished pavement. The length of the project limited possibilities for comparison that would apply to simplified construction procedures; however, the length was not considered an important influence on placement of the base in its relation to improved riding qualities