OCR Text |
Show GRAVEL FOR ROAD BUILDING Simple, Portable Apparatus Devised to Test Its Suitability for Highways. To aid the bureau of public roads, United States Department of Agriculture, Agricul-ture, in giving particular attention to the use of local material for road - j construction wherever possible, a sam-' pie portable apparatus has been devised de-vised for testing gravel to determine Its suitability for concrete. The device de-vice consists of two steel balls arranged ar-ranged so that a piece of gravel can be plac6d on top of one of the balls and the other ball allowed to fall from different heights and strike the gravel. The height of fall required to break the gravel Is an indication of Its suitability to withstand the blows of traffic. Heretofore there has been no satisfactory satis-factory test of gravel as there has been for stone, with the result that In some instances more costly material mate-rial has been used when a suitable gravel was available close at hand. Along this line the bureau Is conducting conduct-ing wear tests on concrete made of many different materials to determine just how far it Is safe to go when the quality of material is doubtful. |