Strength Properties and Microstructural Characteristics of Stabilized Dredged Materials at High Water Contents

Dredged materials (DMs) with high initial water content are often generated during construction projects of ports and waterways, as well as during the dredging of rivers and lakes in China. The cement mixing method is commonly introduced to render these waste materials sustainable earthwork resources. In this study, phosphogypsum is used as a water reducing agent together with cement to stabilize the DMs at high water content. An unconfined compressive strength test, a scanning electron microscopy test (SEM), and a mercury intrusion porosimetry (MIP) test were used in combination to investigate the strength properties and microstructural characteristics of the stabilized dredged material (SDM). It is found that there exists an optimal phosphogypsum content when it is used to stabilize the DMs together with cement. SEM results showed that the strength of the SDM originates from the cementitious bonding and pore-filling of hydration products. MIP results further clarified that total pore volume, average entrance pore diameter, and Dp50 were suppressed with an increase in cementing material content and curing period. The strength properties and microstructural characteristics show a high consistency.