Investigation of construction concepts for pavements across soft ground: final report

This study was a follow-up of a bridge approach study entitled "Investigation of Construction Techniques for Tactical Bridge Approach Roads Across Soft Ground." The objective of this study were (a) to conduct additional tests on the aggregate-membrane concept, (b) to investigate the use of sand-filled confinement grids as an expedient wet weather concent for base course layers, and (c) to analyze and combine the results of this study with those of the Bridge Approach Study. To accomplish these objectives, a test section containing six items was construced and subjected to accelerated traffic using two different loads on a 5-ton military cargo truck. Items 1 through 4 contained sand-confinement grids (sand filled) placed as a base layer over a 1 CBR clay subgrade. It was concluded that collapsible-type sand confinement grids could be developed that would offer an expedient wet weather base course construction technique. A sand-grid base layer for roads and storage areas over soft subgrades would allow design thickness reductions of one third or more. Two membrane aggregate test items were included. Item 5 consisted of a wire-reinforced polyester fabric, and item 6 consisted of a T-16 membrane. Performance of these two items was outstanding. It was concluded that placement of materials such as T-16 membrane or wire-reinforced polyester fabric under even ralatively thin layers of aggregate bases could offer expedient rehabilitation for roads severely damaged by heavy military traffic during wet periods. Performance of a membrane-rehabilitated base layer could equal that of a conventional base layer up to twice as thick.