Shear bond and compressive strength of clay stabilised with lime/cement jet grouting and deep mixing: A case of Norvik, Nynäshamn

The strength of soil can significantly increase by stabilisation with binders. Adding binders in correct proportions to improve soil parameters is of paramount importance for earthworks. In this article, we presented a framework to explore strength characteristics of soil stabilised by several binders and evaluated using applied geophysical methods by estimated P-wave velocities. The core of our work is a systematic assessment of the effects on clay stabilisation from various binders on shear and compressive strength. The binders were combined from four stabilising agents: (i) CEM II/A, a Portland limestone cement; (ii) burnt lime; (iii) lime kiln dust (LKD) limited up to 50%; and (iv) cement kiln dust (CKD). Shear strength has shown a nonlinear dependence as an exponential curve with P-waves. Natural frequency analysis was modelled to simulate resonant frequencies as eigen values. Variations in strength proved that CEM II/A-M (Recipe A, 100% CEM II) has the best performance for weak soil stabilisation followed by the combinations: Recipe B (70% CEM II/A-M, 30% LKD), Recipe C with added 80% CEM II/A-M and 20% CKD, and Recipe D (70% CEM II/A-M 30% CKD). Recipe B has shown high values with maximum uniaxial compressive strength (UCS) at 13.8 MPa. The Recipe C was less effective with the highest value of UCS as 8.8 MPa. The least strength was shown in Recipe D, where UCS has maximal values of 3.7 MPa. The specimens stabilised by Recipe B demonstrated the highest P-wave velocity at 2,350 m/s, while Recipe C and Recipe D showed the highest P-wave velocity at 1,900 and 1,550 m/s. All specimens shown a gain of UCS with sharply increased P-wave speed during the 3 days of curing. The study contributes to the development of methods of soil testing in civil engineering.