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Soil improvements with hydraulic binders are a widespread practice in foundation works. They vary depending on the mixing method (jet grouting hydraulic, deep soil mixing -mechanical), medium type (wet/water, dry/air) and binder type (cement, lime, fly ash or mixtures). The produced component’s strength changes in time thus its control should change in time as well. The paper presents the results of laboratory testing of an organic soil component mixed in dry method. The process of samples preparation and testing methodology of compressive strength and stiffness is described. Volatility of the parameters in time is considered. On the basis of the results, recommendation for optimal quality control time and its methodology for soil-cement components might be proposed.

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The purpose of this paper is to report on the field tests for the formation of a single DR (dynamic replacement) column and its influence on the surrounding weak soil deposit. The influence of the column formation has been assessed with piezocone and dilatometer measurements, as well as by changes in the strength and deformation parameters obtained from the field tests. These measurements were carried out during and after the column formation and at varying distances from the column. The tests carried out have shown that soil close to the column became weaker during the column formation. As a result the soil stiffness and strength were found to increase over time. The weaker the soil was in natural state, the more significant the strengthening effect became. That indicates that changes occurring around a DR column are complex. The measurements suggest that the changes in soil structure have a tendency to be dependent on the distance from the column, elapsed time and the type and the initial condition of the soil.