The Role of Superabsorbent Polymer on Strength and Microstructure Development in Cemented Dredged Clay with High Water Content.

Xia Bian,Xiaozhao Li,Yongfeng Deng,Lingling Zeng

doi:10.3390/polym10101069

Xia Bian, Xiaozhao Li + Show 2 more

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https://doi.org/10.3390/polym10101069

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Abstract

This paper presents the role of superabsorbent polymer (SAP) on strength and microstructure development in cemented clays with notably high water content. A series of unconfined compressive strength (UCS), scanning electron microscope (SEM) and X-ray diffraction (XRD) tests were performed to identify strength behavior and microstructure. Results showed that SAP significantly influenced the mechanical behavior of cemented clays with notably high water content, characterized by an increase in the unconfined compressive strength and a decrease in the after-curing water content with SAP content. This revealed that the strength increase due to SAP was directly related to the water absorption by SAP. Meanwhile, XRD results showed that the hydration products were controlled by cement and lime content, regardless of SAP content. That meant there was no chemical reaction between SAP particles used in this study and cement or lime. The microstructure analysis by SEM revealed that SAP played an important role in the microstructure of cemented clays. With an increase in SAP content, the water absorbed by SAP increased significantly, leading to a decrease in the pore volume and a denser soil fabric. This behavior indicated that the primary role of SAP on strength increase was to absorb and fix water in cemented clays. Consequently, the clay–cement cluster distance decreased with an increase in solid mass (soil particles and swollen SAP particles) and a decrease in pore water. The corresponding tighter flocculated fabric due to SAP eventually led to the strength increase.

Highlights

During the process of dredging from rivers, ports, and harbors, thousands of tons of dredged clays are generated each year
When 1h of superabsorbent polymer (SAP) content was added to cemented dredged clays with notably high water content, qu increased by an average of 0.8 times compared to those without SAP
The significant increase in unconfined compressive strength emphasized that SAP had a positive influence on the strength of cemented dredged clays at notably high water content, with significant improvement on the effectiveness of the cemented mixing method for this specific case

Summary

Introduction

During the process of dredging from rivers, ports, and harbors, thousands of tons of dredged clays are generated each year. By 2015, more than 14 billion m3 of clay materials had been dredged annually from main rivers and commercial ports in China [1]. The number of dredged clays from waterways in the United States was approximately 300 million m3 per year [2,3]. The dredged clays were often classified as waste materials, dumped in the ocean or in a storage yard [4,5]. The large amount of dredged clays may cause severe environmental problems.

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