| dc.description.abstract | The purpose of this study is focused on the sedimentation mechanism and the improved efficiency of cement treated sands with coagulant in water. In order to avoid the separation of cement particles from cement treated sand in the backfilling of free sedimentation mode, the cement treated sands were improved by adding different types of coagulant. In this research, a series of unconfined compression tests and dynamic triaxial tests were carried out for a set of treated sands consisted of different coagulant content (from 0, 86, 344, 600 to 860 mg/kg), different cement contents (1.0%, 2.0%, 3.0%, 4.0%, 6.0% and 8.0%), Portland cement type I and different curing time (by 7, 14, 28, and 56 days). According to the experimental results, the polyacrylamide was the most effective coagulant for reducing the loss of cement. On the other hand, the unconfined compression strength increased initially and then decreased as the dosage increased. The optimum coagulant content is 344 mg/kg. Furthermore, when curing time was 7 days and cement content was 8% or when curing time was 28 days and cement content was 6%, the liquefaction resistance would be significantly increased. The results of this research show that the cement material and polyacrylamide will be contributive to improve the dynamic properties of sands such as shear modulus and cyclic stress ratio . | en_US |