title: Recycling red mud from the production of aluminium as a red cement-based mortar.
abstract: Current management for red mud is insufficient and a new method is needed. A series of experiments have been carried out to develop a new approach for effective management of red mud. Mortars without or with 3%, 6% and 9% red mud were prepared and their fresh and hardened properties were measured to access the possibility of recycling the red mud in the production of red cement-based mortar. The mechanisms corresponding to their mechanical performance variations were explored by X-ray powder diffraction and scanning electron microscopy. The results show that the fresh mortars with red mud present an increase of viscosity as compared with the control. However, little difference is found when the content of red mud is altered. It also can be seen that red mud increases flow time and reduces the slump flow of the mortar. Meanwhile, it is found that mortar with red mud is provided with higher air content. Red mud is eligible to adjust the decorative mortar colour. Compressive strength of mortar is improved when less than 6% red mud is added. However, overall it has a slightly negative effect on tensile bond strength. It decreases the Ca(OH)2content and densifies the microstructure of hardened paste. The heavy metal concentrations in leachates of mortars with red mud are much lower than the values required in the standard, and it will not do harm to people's health and the environment. These results are important to recycle and effectively manage red mud via the production of red cement-based mortar.
authors.affiliation: 1 Key Laboratory of Advanced Civil Engineering Materials Ministry of Education, Tongji University, Shanghai, PR China.
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Yang
authors.affiliation: 1 Key Laboratory of Advanced Civil Engineering Materials Ministry of Education, Tongji University, Shanghai, PR China.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Zhao
authors.affiliation: 1 Key Laboratory of Advanced Civil Engineering Materials Ministry of Education, Tongji University, Shanghai, PR China.
authors.forename: Haoxin
authors.initials: H
authors.lastname: Li
authors.affiliation: 2 Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan, PR China.
authors.forename: Piqi
authors.initials: P
authors.lastname: Zhao
authors.affiliation: 1 Key Laboratory of Advanced Civil Engineering Materials Ministry of Education, Tongji University, Shanghai, PR China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Chen
mesh_terms: D000535:Aluminum; D019245:Compressive Strength; D003252:Construction Materials; D019216:Metals, Heavy; D059027:Recycling
chemical_list: D019216:Metals, Heavy; D000535:Aluminum
keywords: Red mud; leaching toxicity; red cement based mortar; rheological behaviour; strength