Rapid Evaluation of the Pozzolanic Activity of Bayer Red Mud by a Polymerization Degree Method: Correlations with Alkali Dissolution of (Si+Al) and Strength.

Yaguang Wang,Zhiqing Xie,Yang Xue,Xiaoming Liu,Huimin Wang,Wei Zhang

doi:10.3390/ma14195546

Abstract

A large amount of Bayer process red mud is discharged in the process of alumina production, which has caused significant pollution in the environment. The pozzolanic activity of Bayer red mud as a supplementary cementitious material is a research hotspot. In this work, a new method for Fourier-transform infrared spectrometry is used to determine the polymerization degree of Bayer red mud in order to evaluate its pozzolanic activity. Based on the results of the dissolution concentration of (Si+Al), strength index and polymerization degree of Bayer red mud, the relationships between different evaluation methods were analyzed, and the relevant calculation formulas of pozzolanic activity were obtained. The results showed that different evaluation methods can reflect the variation law of pozzolanic activity in Bayer red mud. The polymerization degree of Bayer red mud had a good linear relationship with the pozzolanic activity index obtained by the strength index and dissolution concentration of (Si+Al), respectively. The polymerization degree was negatively correlated with pozzolanic activity index and dissolution concentration of (Si+Al), and the correlation coefficients were greater than 0.85. Therefore, this method was found to be effective and hence can be used as a rapid and simple test for pozzolanic activity evaluation of Bayer red mud.

Highlights

Bayer red mud (RM) is a kind of strong alkaline solid waste discharged in the process of alumina production; about 1–2 tons of RM will be discharged per ton of alumina production [1,2,3]
The phase composition has an important influence on the pozzolanic activity of RM
A new method to evaluate the pozzolanic activity of RM by its polymerization degree was proposed

Summary

Introduction

Bayer red mud (RM) is a kind of strong alkaline solid waste discharged in the process of alumina production; about 1–2 tons of RM will be discharged per ton of alumina production [1,2,3]. The green sustainable development of cement has been a concern of international scholars, and research focus has mainly been on energy conservation, emission reduction and environmental protection, in order to meet the needs of carbon neutrality. Industrial solid wastes, such as fly ash, and blast furnace and steel slag, have been widely used as supplementary cementitious materials in the field of cement and concrete [4,5,6]

Methods

Results

Conclusion