Strength characteristics and microstructure evolution of cemented tailings backfill with rice straw ash as an alternative binder. (23rd August 2021)

• Record Type: Journal Article
• Authors: Wang, Shi; Song, Xuepeng; Wei, Meiliang; Liu, Wu; Wang, Xiaojun; Ke, Yuxian; Tao, Tiejun
• Is Part Of: Construction & building materials. Volume 297(2021)
• Publication Date: 2021-08-23
• Subjects: Strength characteristics -- Microstructure -- Cemented tailings backfill -- Rice straw ash; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.123780
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: It is the first time to use rice straw ash (RSA) to improve the strength of CTB. The compressive strength of CTB with RSA is significantly improved. The RSA can reduce the filling cost and shorten the mining and filling cycle. A new filling system for RSA was proposed. Abstract: Cement is the most commonly used binder in mine filling materials, and it is a key to obtaining the desired mechanical properties of the backfill. However, cement costs often account for 75% of the total operational costs. The objective of this study was to use agricultural waste rice straw ash (RSA) to partially replace cement with a view to reducing the filling cost and yet improving the strength performance of cemented tailings backfill (CTB). The fluidity, strength characteristics, and microstructure evolution of CTB with different RSA replacement levels were measured through experiments. The results indicate the following: (1) The fluidity of the fresh CTB was reduced by the addition of RSA, but it could still ensure pipeline transportation. (2) The uniaxial compressive strength (UCS) of the CTB was positively correlated with the RSA replacement level. As the replacement level of RSA increased, compared to CTB without the RSA, the maximum increase of UCS of CTB with RSA was 46.2, 40.4, and 37.6% at 7, 14 and 28 d curing ages, respectively. (3) As the RSA replacement level increased, the strain in the compaction stage of stress–strain curve was decreased, and the elastic modulus of CTB with ARS was significantly improved. (4) The RSA consumed CH to generate additional C-S-H gel. The bonding strength within the tailings particles was enhanced, more compact microstructure was formed. Simultaneously, the micro aggregate filling effect of the RSA was conducive to further refinement of micro structure of CTB, thereby resulting in improvement of CTB strength. The research results have provided a theoretical and technical basis for the application of RSA in mine filling.