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In geotechnical work, the boundary condition of the load‐bearing safety and the usability is of great importance. The ground must meet the requirements arising from the load on the construction stage and the future use after completion of the construction project. If the pending soil does not meet these requirements, certain measures can be taken. Such soil improvement measures include physical and chemical methods. Minder et al. (2016) explored the concept of enhanced delivery of chemicals for soil improvement applications based on clay treatment by guanidine salt solutions. During the chemical modification, a granular, non‐plastic behavior of the clay was observed. Investigations showed a strong tendency of aggregation of the clay minerals during the treatment leading to silt‐like materials. As a result, a significant increase in shear strength and decrease in the swelling potential of clayey soils was achieved. The question is how efficient the modification is depending on the used cation and clay mineral as well as its sensitivity to saturation/humidity and mechanical impact. In the presented work the aggregate stability of different clays (kaolin, bentonite, silty soil) after different chemical modifications (mainly calcium and guanidine) has been investigated by conducting sieving/dipping tests (DIN 19683‐ 16), laser diffractometer measurements (sensitivity to ultrasonic treatment), by an ultrananoindenter (uniaxial strength test on single aggregates) and by one dimensional consolidation oedometer test (strength measurement on powder). The certain enhancing effect on the aggregate stability was visible for all clay minerals after treatment with guanidine and calcium. A strong improvement of aggregate stability has been reached by modification of smectite with guanidine. With the ultrananoindenter the particle failed at a load of more than 20 mN (sigma > 6 N/mm2 which relates to an overburden load of appr. 200 m). A high strength in the one dimensional consolidation of at least 10 MPa was found for the dry aggregates. In saturated state the increased permeability was maintained even under high confining stresses of up to 800 kPa. These increased permeability and strength even under high confining stresses are very important, they allow the practical applications not only at the surface but even in depth Show more
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Book titleLiving clays: From nano-scale interactions to incorporation in everyday life.
Pages / Article No.
PublisherThe Clay Minerals Society
Organisational unit08669 - Gruppe ClayLab
02607 - Institut für Geotechnik (IGT) / Institute for Geotechnical Engineering (IGT)
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