D E Montgomery, (Apr 1999)
Previous researchers have already expressed their dismay at the lack of information in the field of dynamic compaction of soil blocks. The information that is available on dynamic compaction mainly comes from the civil engineering industry from ground compaction methods. Whilst these are suitable for gaining a basic understanding of soil compaction, they are not entirely applicable to compaction of blocks confined in a mould. Modelling of the compaction process has been attempted within this field and the mathematics for this has been included in this report.
Dynamic compaction of soil blocks without the use of cement has been investigated to establish optimum compaction efficiencies when the energy transfer is kept constant. This has shown that between 8-32 blows gives the greatest compaction for the same total energy transfer. The research does not investigate the effect of adding cement to the compaction process. Research done in the civil engineering industry briefly investigated the effect of moisture on compaction as well as the efficiency of different methods of energy transfer. These results are significant but cannot easily be applied to the research done on block compaction.
Several major gaps in the understanding of soil compaction still exist, and these need to be tackled one by one. It is of fundamental importance that thorough testing of dynamically compacted cement stabilised block be carried out in the near future. Optimisation of energy transfer can yield small increases in density, which result in much greater gains in strength. More time spent researching the optimum method of energy transfer would be a valuable exercise especially with the addition of cement which has an effect on the compaction process