Laboratory Push-In Resistance Tests (PIRT) in a cement-stabilised pseudo-fibrous peat

Deep dry soil mixing (DDSM) is a form of ground improvement in which dry binders are injected and mixed in situ, forming individual columns, rows or interlocking panels, thereby improving the geotechnical characteristics of the host soil. In situ strength verification is required to validate designs and is typically achieved using the Push-In Resistance Test (PIRT). Guidance on PIRT bearing factors is almost exclusively based on Scandinavian experience which has limited confidence in the technique internationally; this has prompted a comprehensive suite of laboratory-scale PIRT verification tests in cement-stabilised clay/silt at NUI Galway (Timoney and McCabe 2017). Given that peat soils can be successfully stabilised and that very little of the collective PIRT experience to date pertains to peat, a small supplementary study of PIRT in stabilised peat was carried out, the results of which are reported in this paper. The PIRT bearing factors inferred for stabilised peat are in keeping with those obtained for clay/silt at comparable stabilised strengths.