Investigation of the structural behaviour and stabilization mechanism of loamy soils stabilized with enzyme additivesTitle of the project

Soil improvement using sustainable and environmentally friendly means has become the focus of research in recent years. Biological stabilization is one of the new techniques in this field, which aims to improve the technical properties of soils by treating them with enzyme additives. However, current research on the engineering properties of clays stabilized with enzyme additives is still insufficient and the results are inconsistent. Although hypothetical stabilization mechanisms and interactions between enzymes and clay minerals have been proposed, these have only been tested to a limited extent in the laboratory. This study aims to complement the experimental investigation of the engineering performance of clays stabilized with enzymes and the exact interaction process to gain insight into the application of enzymes in soil improvement and the experimental exploration of the stabilization mechanism. Two aspects are important here. First, a more comprehensive understanding of the technical performance of soils stabilized with enzyme amendments should be gained. In this section, a series of standard experimental tests will be carried out on the mechanical and physical properties of treated and untreated (control group) soil samples. Subsequent experiments will investigate the effect of influencing factors on performance. The aim is to clarify the optimum application conditions, particularly with regard to the curing temperature, the pH value and the content of enzymes and clay minerals. Durability will then be tested under cyclic wetting/drying conditions. On the other hand, this research project should help to make the stabilization process transparent and to validate the stabilization mechanism of enzyme additives from a microstructural point of view. This requires further investigations, such as X-ray fluorescence (XRF) for the qualitative and quantitative analysis of the active substances involved in the stabilization process and scanning electron microscopy (SEM) to investigate the microstructural variation in connection with the improved mechanical behaviour. The results will then form the basis for recommendations on how enzyme-based soil improvement can be implemented more effectively in typical geotechnical engineering applications.