En laborativ studie om tjälpåverkan på kalkstabiliserad lera och cementstabiliserad sand

Sammanfattning: This project is a Master's Thesis which extent is 30 credits in the specialization Soil and Rock Construction within Civil Engineering at the Technical University of Luleå. The project is a laboratory study, which has been executed at the Technical University of Brunswick in Ger-many.The project has looked into how uniaxial strength of stabilised soil is affected when the mate-rial has been exposed for ground frost. The study also checked whether there is a recovering effect in the material after thaw. The study was performed in laboratory by studying two soils and two stabilisation agents. The materials were a clay stabilised with lime and a silty sand stabilised with cement. Both soils where taken from the Stockholm area in Sweden. In total 108 samples were manufactured with different combinations of content of stabilization agent, hardening time, number of freeze-thaw-cycles and curing time. This resulted in 18 combinations of samples for each soil. The questions the project answered are:impact of freeze-thaw-cycles on the uniaxial compressive strengthif the curing after freeze-thaw can repair the material with respect to its uniaxial compressive strength.The results show that the uniaxial compressive strength of the lime-stabilised clay is reduced by about 40 to 80 %. The magnitude depends on the amount of stabilizer, hardening time and freeze-thaw-cycles. The cement-stabilised sand gets a change of its uniaxial compressive strength by ±10 %. Consequently there is no evidence that the freezing has an impact on the uniaxial compressive strength in this case. After curing of the stabilised clay samples exposed to freezing and thawing the uniaxial compressive strength was found to be 20 to 115% of the original value. Therefore, there is only a small actual recovery in the clay samples. For the ce-ment-stabilised sand a more continuous growth of strength was found rather than recovery during the after curing. This was in the range of about 0 to 25%.The cement-stabilised sand has shown to be brittle and sensitive to deformations. This makes its limitation not to be carrying capacity. The limitations are rather deformation and move-ment.