Compressibility and strength development of geopolymer stabilized columns cured under stress

The objective of this study was to evaluate the effects of geostatic stresses on the compressibility and strength development of submerged geopolymer stabilized columns. In this research study, modified 1D consolidation cells were developed to replicate deep mixed columns in the field when subjected to varying stresses at various depths. Various combinations of fly ash (FA) and slag (S) precursors were used and activated with a liquid alkaline activator (L) to form the geopolymer binder. Soil-column samples were cured under vertical stresses of 0, 50, 100 and 200 kPa for up to 28 days. The results indicated that by increasing the curing stress, the vertical strain and constrained modulus of soil-column composite increased. Moreover, by increasing the binder content, the vertical strain and stiffness of the composites were decreased and enhanced, respectively. The permeability of the composites decreased by increasing the curing stress. The results indicated that addition of the FA+S up to 25% resulted in an increase of permeability and further addition of binder content resulted in insignificant changes in the permeability values. For all the tested geopolymeric binder contents, increasing the curing stress resulted in the enhancement of strength development of stabilized columns. The rate of strength development was enhanced with curing time at an increasing rate, up to 28 days.