Evaluating the effect of soil grading on the UCS of MICP-treated sandy soils

Many past studies have investigated the Unconfined Compressive Strength (UCS) behaviour of MICP-treated sandy soils and developed empirical relationships to predict strength improvement. While the UCS of MICP-treated soils can be affected by many factors such as chemical concentration, temperature, and biochemistry, it has been found that particle size ( d 10 ) is one of the important contributing factors, but most of the previously published studies have not considered it. This study applied MICP on three different variants of Adelaide Industrial (AI) clean sands with different grain size distributions to evaluate the effect on UCS and Calcium Carbonate ( CaC O 3 ) precipitation. To better understand the influence of particle size, this study also collected literature data on UCS, CaC O 3 content and soil grading properties. A numerical method was used to interpolate the distribution of the combined data (literature and experimental) in 3D space to establish a clear correlation between UCS, CaC O 3 content (CC) and the soil grading properties. So, contour plots were generated between UCS, CC, and d 10 and other soil grading properties. Where the 2D and 3D plots could not clearly present the influence of d 10 on the variation of UCS and CC, contour plots presented the distribution rather clearly. The contour plots showed a visible trend in the variation of UCS and CC for d 10 and Coefficient of Curvature ( C c ), but not for Coefficient of Uniformity ( C u ).