Stabilization of Road Embankments on Peat Soils Using Oil Shale Ash and Pozzolanic Additives

Using kukersite oil shale ash for the stabilization of organic-rich soils has been extensively studied but without much success. The main reason for this is the retarding effect of humic acids present in organic-rich soils on the formation of the C-S-H (calcium-silicate-hydrate) phase, which effectively prevents the solidification of cementitious materials in peat soils. Based on the studies performed at the University of Tartu, we have developed a novel method for the in situ mass stabilization of peat soils using waste materials (calcareous fly ash and silica fume). In this manner, the perfect hardening of peat-ash mixtures (to each 1 m(3) of soil, 150-400 kg ash, 25-50 L pozzolanic additives, and 2.5-5 kaNaOH were added) can be achieved. A test road embankment was constructed under extremely hard conditions in a peat quarry that is currently in use.