Effect of very high compaction pressures on the physical and mechanical properties of earthen materials

The paper compares the effect of different compaction procedures on the porosity and mechanical characteristics of earthen materials. In a first series of tests, a very high static pressure, up to 100 MPa, is applied to the soil for a sufficient period of time to allow consolidation (hyper-compaction). This method produces materials with very high densities up to 2300 kg/m3 and good mechanical properties, which are suitable for the construction of masonry structures. In a second series of tests, the soil is compacted according to the standard Proctor method, which is the reference compaction procedure for the design of geotechnical fills such as dams and embankments. In the Proctor method, the soil is dynamically compressed by means of a much lower effort compared to hyper-compaction. All specimens are equalized under identical hygro-thermal conditions and subjected to unconfined compression tests to measure stiffness and strength. It is shown that hyper-compacted specimens exhibit physical and mechanical properties that are comparable with those of traditional building materials for masonry structures. Finally, mercury intrusion porosimetry tests are performed to study the effect of the compaction method on the pore structure of the material.