Effects of Polyacrylamide on the Consolidation Behavior of Dredged Clay

Abstract

Dealing with dredged clay with high water content has become a difficult issue in recent years. The admixture addition of polyacrylamide (PAM) to dredged clay to improve its poor engineering properties has become a trend. This study presents a laboratory investigation of the effects of the addition of polyacrylamide on the consolidation behavior of dredged clay. A series of oedometer tests was conducted on PAM specimens in both normally consolidated (NC) and overconsolidated (OC) states. The test results show that in the NC state, the weak engineering properties of dredged clay were improved by the PAM addition. The initial water content of the samples with PAM after filtration tests decreased by 45% compared to natural samples without PAM. The structural yield stress and coefficient of consolidation of samples with PAM were two times higher than those of untreated samples. A predictable model of the coefficient of secondary compression was obtained for Tianjin Binhai dredged clay. In the OC state, the coefficient of consolidation decreased with the increase in PAM content. An overconsolidation ratio (OCR) of 2. is the threshold value for evaluating the critical settlement between primary and secondary compression. The coefficient of secondary compression decreased linearly with increasing OCR and a linear model for predicting secondary compression is proposed. The addition of PAM can be beneficial (5 mg/L for Tianjin Binhai dredged clay) to accelerate the consolidation process, reduce secondary compression, and reduce project costs.