Jwaneng-Sekoma Road (Botswana)	Nigel-Springs Road (Nigel, South Africa)

Premature failure of pavements under service loading is often associated with poor sub-grade strength beneath the pavement. The cost of repair of such prematurely failed pavements is extremely high as the removal of the pavement layers to enable the treatment of the poor sub-grade prior to the importation of new pavement layers is both costly and time consuming.

The high energy and relatively large depth of influence of the Landpac ground improvement equipment makes it an effective mechanism of compacting such prematurely failed pavements from the existing pavement surface in order to improve the engineering properties of the weak sub-grade materials. This process does “modify” the existing pavement materials at the same time as improving the sub-grade materials. Typically, the existing surface, sub-base and base layers of a pavement being treated using the Landpac high energy compaction equipment are converted into “granular sub-base layers”. The high energy compaction process leads to a good balanced strength throughout the depth from the surface of the pavement down through the existing pavement layers and into the improved sub-grade material. This can then be used as a sub-base, upon which a new base layer and surfacing layer can be placed in order to complete the pavement rehabilitation process.

The added capability of the Landpac CIR and CIS systems to provide a quantitative measurement of the pavement response and settlement during the rehabilitation process, allows for accurate identification of the relative strength of the entire area being treated. This enables an objective assessment to be carried out that can be utilised for pin point testing and accurate identification of any potential problem areas.

Pavement rehabilitation utilising the Landpac high energy ground improvement technologies has proven to yield cost and time savings of up to 60% when compared to conventional rehabilitation methods.