The purpose of this project was to investigate the suitability of rockbust, stabilised with cement in the form of a flowable slurry for the blackfilling of trenches, either transversal or longitudinal,over which there will be an asphaltic pavement. The slurry would have to comply with the specifications laid down by the Ministry of Public Infrastructure (MPI) which are : the 4-days soaked CBR at 95% BS Heavy companion should not be less than 10%, the plasticity index should not be more than 25% and the liquid limit should not be more than 35%.