This study is aimed at evaluating the strength of stabilised soil col- lected from the Port of Norvik, Stockholm, Sweden, where 350,000 m3 of clay had to be stabilized. The tests were performed in the lab- oratory of the Swedish Geotechnical Institute (SGI). The soil was sta- bilised by binder mixtures using Portland cement clinker (PCC) and lime and lime kiln dust (LKD). Accelerators (X-seed 100 BASF, PCC, LKD and salt) were added to the soil samples for quicker stabiliza- tion. The strength of the stabilised soil was assessed using resonance frequency measurements of seismic P-waves by an ICP accelerom- eter in order to estimate the shear strength of the soil and to eval- uate the effects from the accelerators, binder ratios, and the curing temperature on the gains in stabilization and strength. Various proportions of the binders were tested, i.e.: 50/50 cement/lime and 50/50 PCC/lime. The temperature was measured using a calorimeter in double experiments. The results showed that the accelerators improve the strength in the stabilized specimens and enhance the soil performance for engineering construction work.