This project made use of six bituminous materials and ten aggregate gradations in plant mix paving operations. The test sections were installed by state forces in 1942 and 1943. The object was to determine which aggregate gradation with a specific bituminous material was best suited for an application of 75 pounds per square yard surface treatment.

The bituminous materials used were MC-5, RC-5, RT-12, PAC-5 (85 to 100 penetration), PAC-7 (120 to 150 penetration), and PAC-8 (150 to 200 penetration). Twenty sections of MC-5 and ten sections of RC-5 were laid in 1942; all the sections containing the other materials were placed in 1943. A lay-out of the project by sections is shown in Fig. 1.

There were three aggregates or aggregate combinations as follows: Limestone, Limestone and Concrete Sand, and Limestone and River Sand. The Limestone type consisted of four gradations made from mixing No. 9 and a fine stone designated as No. 11F. The Limestone and Concrete Sand type consisted of three gradations of No. 9 stone and the coarse sand. The Limestone and River Sand type consisted of three combinations of River Sand and No. 9 stone. These ten gradations are outlined in Table 1 and shown on the gradation chart in Fig. 2.

The gradation range for the 11F stone used in gradings G-1 to G-4 is in Table 1A. This was a much finer stone than the present No. 11 outlined in the same table. A plot of these gradation ranges along with one representing the Kentucky River sand is presented in Fig. 3.

Report Date


Report Number

No. 68

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