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Near-surface soil stabilisation to reduce the frost susceptibility of soft soils

Av: Språk: Engelska Språk på sammanfattning: Svenska Serie: Licentiate thesis / Luleå University of TechnologyUtgivningsinformation: Luleå : Luleå University of Technology, 2018Beskrivning: 96 sISBN:
  • 9789177902317
  • 9789177902300
Annan titel:
  • Ytstabilisering av terass för att minska påverkan av frysning
Ämnen: Onlineresurser: Avhandlingskommentar: Lic.-avh. (sammanfattning), 2018 Abstrakt: Fine-grained soils are normally not suitable as subsoil for roads or railways or other largescale constructions; clayey soils mostly because of theu- often soft consistency, but for silty soils, the main reason is theu- frost susceptibility. Frost resistance as well as engineering properties of these soils can be improved by stabilising them with hydraiilic binders. Stabilisation is quite often used in countries with moderate climate to improve the bearing capacity and to reduce the frost susceptibility of fine-grained soils. However, the frost influence on stabilised soil is unclear, which leads to reduced usage of the method in countries with cold climate. This licentiate thesis presents a literature review and two laboratory series in order to analyse the potential use of the method in cold region climate. The laboratory series were performed with two in Sweden common fine-grained soil types, clay and silty sand. One series deals with clay stabilised with a hydraulic binder that is new for this purpose and originates as a by-product from iron extraction. The other series deals with silty sand stabilised with a cement mixture for soil stabilisation, containing 50% portland cement and 50% cement kiln dust (CKD). The thesis is focusing on the impact of frost on the properties of stabilised soils, considering different binder contents, in relation to the properties of the unstabilised soils. In addition, the importance of the curing times and curing temperature is also evaluated. Three different curing times were tested, i. e. 14, 28 and 90 days. The curing took place at a temperature of +4°C to simulate the soil temperature in northern Sweden. The unconfined compressive strength (UCS) was used as a measure of strength. One third of the samples was tested without freeze-thaw, one third was conducted to twelve freeze-thaw-cycles and tested directly after the last thawing, and one third was conducted to twelve freeze-thaw-cycles and then kept under the same curing conditions as before for another 28 days before testing.
Exemplartyp: Licentiatavhandling
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Lic.-avh. (sammanfattning), 2018

Fine-grained soils are normally not suitable as subsoil for roads or railways or other largescale constructions; clayey soils mostly because of theu- often soft consistency, but for silty soils, the main reason is theu- frost susceptibility. Frost resistance as well as engineering properties of these soils can be improved by stabilising them with hydraiilic binders. Stabilisation is quite often used in countries with moderate climate to improve the bearing capacity and to reduce the frost susceptibility of fine-grained soils. However, the frost influence on stabilised soil is unclear, which leads to reduced usage of the method in countries with cold climate. This licentiate thesis presents a literature review and two laboratory series in order to analyse the potential use of the method in cold region climate. The laboratory series were performed with two in Sweden common fine-grained soil types, clay and silty sand. One series deals with clay stabilised with a hydraulic binder that is new for this purpose and originates as a by-product from iron extraction. The other series deals with silty sand stabilised with a cement mixture for soil stabilisation, containing 50% portland cement and 50% cement kiln dust (CKD). The thesis is focusing on the impact of frost on the properties of stabilised soils, considering different binder contents, in relation to the properties of the unstabilised soils. In addition, the importance of the curing times and curing temperature is also evaluated. Three different curing times were tested, i. e. 14, 28 and 90 days. The curing took place at a temperature of +4°C to simulate the soil temperature in northern Sweden. The unconfined compressive strength (UCS) was used as a measure of strength. One third of the samples was tested without freeze-thaw, one third was conducted to twelve freeze-thaw-cycles and tested directly after the last thawing, and one third was conducted to twelve freeze-thaw-cycles and then kept under the same curing conditions as before for another 28 days before testing.