Abstract
In order to reuse red mud and bauxite tailings mud (two typical aluminum industrial wastes) to reduce the occupation of land resources and environmental damage, these two wastes were combined to develop subgrade materials for the first time. With different combinations, the effects of the amounts of red mud, tailings mud, and cementitious materials on the strength of tested subgrade materials were investigated. The mechanism of strength growth was analyzed by a micro-test. The test results showed that the material strength of three combinations met the requirements when the unconfined compression strength (UCS) of all combinations increased with age. The UCS of the A1BC2 combination (the mass ratio of red mud and tailings mud was 2:1, the mass ratio of cement and quicklime was 1:1, and the mass ratio of waste and cementitious materials was 1:0.2) was the best, with the UCS being 3.03 MPa in 7 days. Microscopic imaging showed that specimens with high red mud contents had compact structures without cracks. The strength of these materials is mainly due to hydration reactions and pozzolanic reactions; the cementitious products generated by the reactions solidify Na+ and inhibit the release of OH−, while the addition of tailings mud can reduce the content of Na2O in the material, which makes the environmental compatibility of the A3BC2 combination the best (the mass ratio of red mud and tailings mud was 1:2, the mass ratio of cement and quicklime was 1:1, and the mass ratio of waste and cementitious materials was 1:0.2). Its pH value was 8.75. This experiment verifies the feasibility of the combined application of red mud and tailings mud in subgrade materials. To this end, a feasible scheme for the simultaneous consumption of these two kinds of aluminum industrial wastes has been proposed.
Highlights
Aluminum is one of the most widely used nonferrous metallic materials in the world.In the production of aluminum, two wastes are generated in large volumes: red mud and bauxite tailings mud
In order to eliminate the adverse impacts of these wastes on land resources and the ecological environment, it is of significance to find an economical way to utilize large amounts of red mud and bauxite tailings mud, especially in subgrade engineering
The results provide an important construction cost of subgrade engineering and realize the reuse of waste and the line for the application of red mud and tailings mud to subgrade engineering
Summary
Aluminum is one of the most widely used nonferrous metallic materials in the world. In the production of aluminum, two wastes are generated in large volumes: red mud and bauxite tailings mud. The utilization of red mud mainly surrounds three aspects: extracting tion gypsum, etc.) can meet the application requirements of low-grade road subgrade ma valuable metals from the red mud [8,9]; using red mud as an adsorbent or catalyst for terials under remediation the condition adding[10,11,12]; certainand additives and Mohanty environmental and of treatment using red[16]. The mechanical properties of pure red mud or a 2.9, the combination of red mud and industrial wastes Red mud to develop subgrade materials can reuse those two wastes and re Both bauxite tailings mud and red mud are stored in alumina production enterprises, duce environmental hazards. The results provide an important guideline for the application of red mud and tailings mud to subgrade engineering
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