Mechanical Properties and Microstructure Characteristics of Submerged Cement-Based Stabilized Marine Soft Clay Enhanced with ISS and PAM

The traditional cement-based stabilization cannot effectively stabilize the marine soft clay under submerged conditions. In order to solve this problem, the enhancement of cement-stabilized marine soft clay was investigated in this study by adding the ionic soil stabilizer (ISS) and polyacrylamide (PAM). For this purpose, varying contents of ISS and PAM (ISS-P) were added into cement-stabilized marine soft clay and subjected to curing under submerged conditions. Atterberg limits tests, direct shear tests, unconfined compression strength (UCS) tests, water-stability tests, scanning electron microscopy analysis, and X-ray diffraction analysis were carried out. The results show that using 1.8% ISS and 0.9% PAM as the optimal ratio, the cohesion, internal friction angle, UCS, and water-stability of the samples increased by 182.7%, 15.4%, 176.5%, and 368.5% compared to the cement-stabilized soft clay after 28 d. The increment in soil cohesion with increasing ISS-P content was more apparent than that in the internal friction angle. The combined action of ion exchange attraction and electrostatic adsorption altered the failure characteristics of the samples, resulting in localized micro-cracking and multiple failure paths. Increasing the content of ISS-P strengthened the skeletal structure of soil, reduced inter-particle spacing, and enhanced the water-stability. Additionally, ISS promotes the hydration of cement and compensates for the inhibitory effect of PAM on early cement hydration. ISS-P can effectively enhance the strength and stability of submerged cement-based stabilized marine soft clay.