This study considers a method for evaluation of porosity of biogrouted geomaterials. First, we visualized the internal structures of the specimens by using micro-focused X-ray CT scanner. We tested Souma sand, gum tips, plastic pellets, steel balls and glass beads as geomaterial to find suitable geomaterials for evaluation of porosity: geomaterials whose CT-number histogram was bimodal. The results clarified that one of the geomaterials, glass beads whose particle size was 0.50-0.71mm, was suitable for evaluation of porosity. Second, we calculated the porosity of the glass beads by using a method for evaluation of porosity based on a maximum likelihood thresholding method considering the effect of mixels. The result showed that the ratio of the porosity of grouted geomaterial to that of ungrouted geomaterial was 0.98 to 0.99. On the other hand, the value estimated by the measurement of changes in concentration of calcium ion was 0.98. Thus, both values closely agreed. Therefore, this study clarifies that the method enables us to evaluate small change in porosity with great accuracy.
