Abstract: Soil stabilizer can be used to improve the properties of soil. In this study, the water stability and stabilization mechanism of silty sand stabilized by modified carboxymethylcellulose (M-CMC) were investigated via disintegration test of stabilized silty sand dosed with varying content of M-CMC. Monitoring of disintegration and measurement of complete disintegration coefficient (C_R) of soil samples suggest that with the augment of M-CMC dosage, the incipient time of disintegration delayed, the content of coarse particles increased, sediment in suspension decreased and the value of C_R dropped sharply; no disintegration was observed when the content of M-CMC reached 0.9%. Furthermore, results of infiltration, matric suction, shear strength, chemical composition and microstructure showed that the size of aggregates increased, infiltration coefficient reduced, suction and shear strength both enhanced together with the increasing of M-CMC content, thereby revealing “membrane effect” on the surface of soil particles, “absorption effect” between adjoining particles, and “bonding effect” between aggregates from M-CMC. As a result, the cementation between particles transformed from point contact to line and plane contact, and single particles changed to aggregates with net cementation, which modified the water stability of soil.

Key words: silty sand, modified carboxymethylcellulose, reinforcement agent, cementation, structural aggregate, water stability, stabilization mechanism