Annual Report of the Indiana State Board of Agriculture, Volume 26: 246 (1885)

Road Paving Material (extract)
John T. Campbell,
Surveyor and Civil Engineer

Charcoal will also make a fair paving material. I will not claim that it is as good as good gravel, but it is as good as average, and better than poor gravel. Timber is often plenty where good gravel, or any kind, is scarce. In large quantities it can be made and sold at the pit at three to three and a quarter cents per bushel. Five to seven yards can be hauled at a load, which about offsets the cost of cutting and burning. It absorbs and rapidly evaporates water and moisture, hence giving a dry road soon after the rains cease. It should be covered with a thin coat of good gravel, to hold it down, from blowing and washing away and from taking fire.

My experiments have been limited to short spaces, and at my own expense, for I could not persuade the Board of Commissioners to risk it as a paving material, and there is generally opposition enough to the road built strictly according to law, without risking the use of unusual material. As the law now reads, any good paving material may be used. But my experiments were very satisfactory. Gillespie's Manual of Roads and Railroads mentions three roads made entirely of charcoal, and pronounces them eminently successful.

A bushel of charcoal, when packed, is equal to about one and one-third cubic feet. To build a mile of road, one foot deep and twelve feet wide of charcoal will require about 48,000 bushels of charcoal which, at three cents per bushel at the pit, will cost about $1,470. The average haul in Parke county would not exceed one mile. At three dollars per day for teams, it can be hauled one mile for twelve cents per cubic yard, including loading, or $250 per mile. A cheaper, and quite good road might be built of charcoal nine inches deep by ten feet wide, covered with three inches of gravel.

The braize, or burnt dirt, which covers the coal pits, is a good paving material, and might be used instead of gravel to hold the charcoal down, as before mentioned.

Charcoal has one merit above all other paving material I know of, that of being as good after it is ground into a dust as when in lumps; it still maintains its compactness. It also has the merit of admitting more mud without becoming slushy than any other material.