Influence of Degree of Saturation on Bearing Capacity and Compaction of Glacial Till Embankments

Abstract

In Sweden the consumption of aggregate each year equates to eight tons per capita and is responsible for half of all goods transportation in Sweden. Approximately 20
million tons of aggregate material is transported to different road construction sites each year. With a more balanced and active design code site-won materials could be utilised as an
alternative to imported rock fill. This would not only reduce transportation costs but also minimise impact on the environment. This paper explores the possibility of utilising site-won
glacial till in road pavement construction above the current permitted level of capping layer level. The bearing capacity of glacial till at three different sites is investigated with
corresponding laboratory tests on compaction properties, since compaction is a crucial factor in the bearing capacity obtained. Results are compared with the criteria specified in the
Swedish design code for each structural road layer. It will be shown that a fill with moderate fines content, compacted close to its optimum water content, meets the requirements for a
sub-base material on bearing capacity. This is due to the influence of negative pore pressure and its positive impact on shear strength. Certain areas of uncertainty remain such as frost
susceptibility and the effects of seasonal variation on degree of saturation beneath a paved construction and should be tackled in the future. To enable future implementation of tills in
structural road layers a new approach to managing fills on site is required which covers crucial issues such as weather conditions and timing of the construction works.