Abstract: Assessing the effectiveness of grouting expansive soil cracks presents a formidable challenge in the field of engineering. In this study, we employed micro-CT scanning technology to quantitatively evaluate the grout filling effect of cracks within expansive soil specimens. Slurries of ultra-fine cement and expansive soil with varied dosage was utilized to grout the cracks. CT scans were conducted before and after grouting to obtain internal slice images, which were then subjected to three-dimensional reconstruction and post-processing analysis. The grouting effect of expansive soil cracks and the minimum width of groutable cracks were quantitatively analyzed using overall porosity, layer-by-layer porosity, pore equivalent diameter, and groutable index. The results illustrated that the groutability of slurry improves with an increase in the water-solid ratio. A water-solid ratio of 1.2 can reduce the overall porosity of expansive soil samples by over 99%, and the minimum crack width for a slurry with an ultra-fine cement content of 50% is 0.6 mm. This method provides a reference for quantitatively evaluating the grouting and filling effects of various slurries in expansive soil cracks.

Key words: expansive soil, CT scan, porosity, grouting materials, crack