ABSTRACT

Many road in Indonesia are constructed over the montmorillonite soil sub-grade, like most of the road in the North-East of Central Java Province. Montmorillonite for most of the road engineering means problems. Those are proved by occurring of road deteriorations which laid over montmorillonite sub-grade in early of its service life especially deterioration in the form of plastic or permanent deformation. Some effort have already been done to overcome that problems, among other thing by constructing of cross drainage to prevent the water keep in the sub-grade layer, by stabilizing sub-grade soil with lime, and by utilizing of conventionally geo-textile to uniformly spread the load and to add it’s bearing capacity, but all of those effort are not succeed the plastic deformation are remain occur. In this paper utilizing of Closed-Tie System on Sub-base course layer with woven geo-textile in flexible pavement over montmorillonite soil or expansive clay will be described and analyzed. From the analysis known that the sub-base course layer with woven geo-textile in can form stiff and stable foundation layer such a way so that the stress in the layer can be carried by the soft soil sub-grade underneath. Those conditions also can be interpreted as increasing of the sub-grade bearing capacity. As the result, the thickness of the pavement also reduces proportionally, and in additional, the pavement could withstand the traffic load during the design of service life without plastic deformations occur.

Key word: montmorillonite, deformation, road, pavement