Abstract:In order to effectively use sludge and promote the development of artificial reefs, artificial reefs were made from sludge, cement and shell powder as raw materials according to different water-cement ratio and shell powder content. The nutrient salt precipitation and the pH value of the soaked seawater were tested. The hydration products of the reef were microscopically analyzed by SEM and XRD. The test results show that: in the range of water-cement ratio 0.5 to 0.6 and shell powder content 0.2 to 0.6, lower water-cement ratio or higher shell powder content can lead to higher strength of the reef block; Adding sludge to reef blocks can continuously precipitate NH4+ and PO43-, and the precipitation law is all linear, but when the proportion of materials changes, there will be differences between these linearity; The higher the strength of the reef block, the closer to the PH value of the seawater immersed in ordinary seawater, the better the hydrophilicity; The formation of ettringite and C-S-H gel by reef block hydration is an important guarantee of reef block strength. This research can provide ideas and technical references for the resource utilization of sludge and the new development of artificial reef materials.