Strength development mechanism of a marine binding material with red mud and seawater

This experiment works on red mud, blast furnace slag, desulfurized gypsum, fly ash, and seawater as raw materials to make a marine binding material. It is found that using seawater as mixing water in red mud based binding materials can promote the strength development comparing to using freshwater. The optimal ratio of red mud, blast furnace slag, cement, desulfurized gypsum, fly ash and externally polycarboxylate superplasticizer is 30%, 19%, 40%, 6%, 5% and 1.5%, respectively. Under the seawater to binder ratio of 0.33, the compressive strength of mortar specimen can reach 36.34 MPa, and the flexural strength can reach 11.32 MPa on the 28th day. Microstructural characterization results indicate that under the double stimulation of alkalinity from red mud and compound salts from seawater, more and more active ions of silicon and aluminum are released to form C-A-S-H gel and ettringite during the hydration of marine binding material. The micro-aggregate filling effect of red mud and hydration acceleration provided by the compound salts in seawater can improve pore structure of the hardened marine binding material. The utilization of red mud in this work can fulfill the green concept of development and avoid potential risk of environment pollution.