Performance Study of Bayer Method Red Mud Based Controlled Low Strength Alkali Inspired Concrete

Abstract

In order to reduce the negative impact of red mud accumulation on the environment, we will recycle red mud to prepare concrete.The controlled low-strength materials were prepared by using red mud, fly ash, and ground granulatedblast furnace slag(GGBS) as raw materials, NaOH as an exciter and polycarboxylic acid water reducing agent as a dispersant, and the working and mechanical properties of the materials were investigated at different ratios of red mud and fly ash. When the mass ratio of red mud to fly ash was 2:1, the dosing of GGBS was 10% and the dosing of NaOH was 1.5%, the maximum flow rate of the mix was 236 mm and the maximum unconfined compressive strength of the specimens at 28 d was 6.5 MPa, which satisfied the specification requirements of controllable low-strength materials. XRD, FTIR and SEM were used to investigate the mineral composition and microstructure of the controllable low-strength material. It was found that the hydration of red mud, fly ash, and GGBS under the action of NaOH formed C-S-H, calcium alumina (AFt), and a small amount of hydrated calcium sulfate, C4 AF; The strength development of materials is closely related to the flocculent, honeycomb, and lamellar structures of hydration products.  The results of this study provide a new technological approach to industrial solid waste scaling in the field of controlled low-strength materials.