Mechanical properties of cemented tailings backfill containing alkalized rice straw of various lengths

Shi Wang; Xuepeng Song; Qiusong Chen; Xiaojun Wang; Meiliang Wei; Yuxian Ke; Zhihua Luo

doi:10.1016/j.jenvman.2020.111124

Mechanical properties of cemented tailings backfill containing alkalized rice straw of various lengths

J Environ Manage. 2020 Dec 15:276:111124. doi: 10.1016/j.jenvman.2020.111124. Epub 2020 Aug 29.

Authors

Shi Wang¹, Xuepeng Song², Qiusong Chen³, Xiaojun Wang¹, Meiliang Wei¹, Yuxian Ke⁴, Zhihua Luo³

Affiliations

¹ School of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000, China.
² School of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000, China. Electronic address: sxp9612@126.com.
³ School of Resources and Safety Engineering, Central South University, Changsha, 410083, China.
⁴ School of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000, China. Electronic address: cqdjliuyue@sina.com.

PMID: 32871463
DOI: 10.1016/j.jenvman.2020.111124

Abstract

The tailings and rice straw that are produced in large quantities each year in the mining and agricultural industries, respectively, have significant effects on the ecological environment. This study aimed to explore the mechanical properties of cemented tailings backfill (CTB) mixed with alkalized rice straw (ARS) of different lengths. A series of uniaxial compressive strength (UCS) and indirect tensile strength (ITS) tests were conducted on the CTB. The results indicated that as the length of the ARS increased from 3 to 15 mm, the UCS and ITS values initially increased and then decreased. The critical length of the ARS was 12 mm, for which the effect of strength increase was the most significant. From the overall analysis, the UCS of CTB samples with ARS (9 and 12 mm) demonstrated the better improvement (increased by 10.0 and 14.7%, respectively) at 28 d curing age, and the improvement effect of the CTB samples with ARS of other lengths was not ideal. The ITS of CTB samples with ARS increased (except for an ARS length of 3 mm) regardless of the curing age; the maximum increase was approximately 24.2% at 28 d. The integrity, residual strength, and toughness of CTB sample with the ARS (12 mm) were the largest after the UCS test. Scanning electron microscopy (SEM) tests indicated that the surface of the ARS was covered with cement hydration products, and the interior of the ARS was filled with cement tailings, which produced stronger adhesion between the ARS (12 mm) and CTB matrix; the ARS performed a bridging role and suppressed crack propagation, which effectively improving the mechanical properties of CTB. Significantly short ARS exhibited a lower adhesive force with the matrix, and significantly long ARS exhibited a lower filling rate. Thus, while improving the mechanical properties of CTB, ARS provides a new method for treating rice straw and decreasing its combustion pollution.

Keywords: Alkalized rice straw; Cemented tailings backfill; Different lengths; Strength.

MeSH terms

Compressive Strength
Construction Materials
Environmental Pollution
Mining
Oryza*