Effect of polypropylene fiber and coarse aggregate on the ductility and fluidity of cemented tailings backfill

Abstract

Adding polypropylene (PP) fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling (CTB) body. It is essential to explore the influence of tailings-aggregate ratio and fiber content on the mechanical properties of CTB samples. The comprehensive tests of the unconfined compressive strength (UCS), slump and microstructure were designed, and the regression models were established to characterize the effect of the strength, ductility and fluidity. The results indicate that the tailings-aggregate ratio of 5:5 and PP fiber content of 0.5 kg/m³ are the optimum point considering the UCS, cracking strain, peak strain and post-peak ductility. The tailings-aggregate ratio is consistent with the unary quadratic to the UCS and a linear model with a negative slope to the slump. Microstructural analysis indicates that PP fiber tends to bridge the cracks and rod-mill sand to serve as the skeleton of the paste matrix, which can enhance the compactness and improve the ductility of the CTB. The results presented here are of great significance to the understanding and application of coarse aggregates and fibers to improve the mechanical properties of CTB.

Keywords

cemented tailings backfill / polypropylene fiber / coarse aggregate / unconfined compressive strength / post-peak ductility / fluidity

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