Evaluating soil strength by geophysical methods using P-waves was undertaken in this study to assess the effects of changed binder ratios on stabilization and compression characteristics. The materials included dredged sediments collected in the seabed of Timrå region, north Sweden. The Portland cement (Basement CEM II/A-V, SS EN 197-1) and ground granulated blast furnace slag (GGBFS) were used as stabilizers. The experiments were performed on behalf of the Svenska Cellulosa Aktiebolaget (SCA) Biorefinery Östrand AB pulp mill. Quantity of binder included 150, 120 and 100 kg. The properties of soil were evaluated after 28, 42, 43, 70, 71 and 85 days of curing using applied geophysical methods of measuring the travel time of primary wave propagation. The P-waves were determined to evaluate the strength of stabilized soils. The results demonstrated variation of P-waves velocity depending on stabilizing agent and curing time in various ratios: Low water/High binder (LW/HB), High water/Low binder (HW/LB) and percentage of agents (CEM II/A-V/GGBFS) as 30%/70%, 50%/50% and 70%/30%. The compression characteristics of soils were assessed using uniaxial compressive strength (UCS). The P-wave velocities were higher for samples stabilized with LW/HB compared to those with HW/LB. The primary wave propagation increased over curing time for all stabilized mixes along with the increased UCS, which proves a tight correlation with the increased strength of soil solidified by the agents. Increased water ratio gives a lower strength by maintained amount of binder and vice versa.

Due to the increasing necessity of building on soils with insufficient bearing capacity, the development of methods for soil improvement is an important geotechnical engineering issue. One of the innovative methods of soil stabilisation is the use of nano-additives. The paper presents the influence of nanosilica on the bearing capacity under the footing under undrained conditions. For this purpose, a simple and quick unconfined compression test was used to evaluate the undrained shear strength of selected silty soil. Tests were conducted for soil without additives and with nanosilica contents of 1, 3 and 5%. All samples were compacted to the maximum dry density in a Proctor apparatus, and strength tests were conducted after 7 days of curing. The results clearly show an increase in undrained shear strength with increasing nanosilica content. Based on these data, a parametric analysis of the bearing capacity under the strip footing was performed for 4 variants of nanosilica content and for 9 loading cases. Thus, the impact of stabilisation in a practical engineering issue was presented. For all load cases the optimal dimensions of the foundation were determined. In addition, for the selected case, calculations were made for a fixed foundation dimension. All computations were performed in accordance with Eurocode 7 with GEO5 software.

Soil stabilization techniques are widely used for road construction to improve the properties of the subgrade materials. Using new additives and stabilizers to improve soil properties can reduce the costs of construction and reduce the possible negative effects of these materials on the environment. The purpose of this study was to evaluate the use of a liquid based nano-material called EarthZyme (EZ) and cement kiln dust (CKD) as admixtures to improve the soil properties. A mixture of two soils was used in this study which were prepared from mixing sand soil and fine-grained soil. Compaction tests were performed on the soil that was stabilized with the CKD to determine the density-water content relationships. Unconfined compression tests were also conducted on specimens without treatment, specimen treated with the CKD only, and specimens treated with the CKD and the EZ after curing period for seven days. The obtained results indicated that adding the CKD to the soil decreased the values of the unconfined compression strength (UCS) from 5 to 15 percent. However, adding the CKD reduced the maximum dry density (MDD) from 10 to 12 %. As discussed herein, soil stabilization with the EZ had insignificant effects on the results obtained from the unconfined compression test.