There is no unified view on the strength development mechanism of chemically grouted sand, which has not been clarified yet. This study investigated the cohesion and friction angle, which are the shearing strength components of the chemical grouted sand, using a consolidated drained triaxial compression test. The microscopic molecular structure of the hydrogels in which the grout gelled itself was analyzed using a small angle x-ray scattering. In the experiment, we used a type of chemical grout that gelled in the non-alkaline region and caused macro volumetric shrinkage. As a result of the triaxial compression test until 300 days, the strength development of the grouted sand added cohesion and increased friction angle because of the fixed soil particles. And these values did not decrease. In the void of soil particles, neither volumetric shrinkage nor peeling of the hydrogel occurred. These suggest that the effect of fixing the soil particles continues. On the other hand, it was confirmed that the aggregation structure became smaller in microscopic molecular structure.
