Abstract
Increasing amounts of tailings and waste rubber tires have caused threats to the environment. In order to reuse these solid wastes, this study proposed a cemented tailings material containing crumb rubber recovered from waste tires. Unconfined compression tests and thermal conductivity measurements were conducted to evaluate the feasibility and performance of the proposed cemented tailings. Results revealed that the stress-strain behavior of the cemented tailings changed by the inclusion of crumb rubber. The unconfined compressive strength of cemented tailings decreased with increasing crumb rubber content. The inclusion of crumb rubber increased the failure strain and nonlinearity index of the cemented tailings. It was found that the addition of 4% crumb rubber provided the greatest improvement in ductility. The increase of the rubber content further increased the thermal insulation capacity of the cemented tailings. The low stiffness and the dimpled surface of the crumb rubber were responsible for the reduced compressive strength and thermal conductivity of the cemented tailings. In conclusion, the crumb rubber had both positive and negative effects on the cemented tailings. In practical application, the rubber admixture amount should be flexibly adjusted for different use case to make the cemented tailings material show the most suitable performance characteristic.
Highlights
There were few studies on the use of tailings as the sole aggregate for cementitious materials. ere were only some studies that showed that the tailings were suitable to be used as the sole aggregate of cemented tailings backfill materials for backfilling the mining stope and improving the ground stability and safety [10, 11]
The stress will be concentrated on the voids in cemented tailings and produce many small cracks around the crumb rubber to alleviate the stress concentration in the cemented tailings. ese effects will prevent the sudden failure of the cemented tailings caused by the stress concentration on the major cracks and improve their ductility
On the basis of the achieved findings, following conclusions could be drawn: (1) e stress-strain behavior of cemented tailings was affected by the inclusion of crumb rubber. ere were more pronounced pore compaction stages and plastic stages in the stress-strain curves of higher rubber content cemented tailings. (2) e unconfined compressive strength of cemented tailings decreased as the crumb rubber content increased
Summary
There were few studies on the use of tailings as the sole aggregate for cementitious materials. ere were only some studies that showed that the tailings were suitable to be used as the sole aggregate of cemented tailings backfill materials for backfilling the mining stope and improving the ground stability and safety [10, 11]. For the past few years, researchers have put great efforts to improve or modify the ordinary cemented tailings backfill material by adding additives [14,15,16]. Chen et al [18] conducted unconfined compressive strength tests on cemented tailings containing polypropylene fiber and the results indicated that the fiber can improve the ductility and stiffness of cemented tailings. Previous researchers have investigated the feasibility of adding waste tire crumb rubber in the cementbased materials such as concrete and cement treated clay [21, 22]. Compared to the low strength cemented tailings backfill used solely for underground voids filling, the investigated cement contents of cemented tailings material were set relatively higher in this study to study the feasibility as a more widely used filling material. Unconfined compression tests and thermal conductivity measurements were conducted on cemented tailings samples. e performance of the cemented tailings was optimized by changing the content of crumb rubber
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