Effect of polypropylene fiber content and fiber length on the saturated hydraulic conductivity of hydrating cemented paste backfill. (30th November 2020)

• Record Type: Journal Article
• Authors: Chakilam, Sirisha; Cui, Liang
• Is Part Of: Construction & building materials. Volume 262(2021)
• Publication Date: 2020-11-30
• Subjects: Cemented paste backfill -- Polypropylene microfiber -- Saturated hydraulic conductivity -- Fiber reinforcement -- Tailings; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2020.120854
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Effect of fibre length and fibre content on hydraulic conductivity is identified. Fibre inclusion mainly affects the initial value of hydraulic conductivity. A predictive model for hydraulic conductivity is proposed. Abstract: Polypropylene fiber reinforcement is considered a promising technique in the mine backfilling operation. However, after placement into underground mined-out space, the hydraulic process affects the mechanical stability of polypropylene fiber-reinforced cemented paste backfill (FR-CPB, an engineered mixture of tailings, binder, water and fibers). Therefore, as a key hydraulic property, the saturated hydraulic conductivity must be quantitatively evaluated for the design of FR-CPB. Correspondingly, a laboratory study was performed in this study to investigate the effect of fiber length (6 mm, 9 mm, and 13 mm), fiber content (0.25%, 0.50%, and 0.75%), and curing time (3, 7, 28, and 90 days) on the saturated hydraulic conductivity of FR-CPB. It has been found that the random distributed discrete fiber mainly affects the initial value of hydraulic conductivity, while the cement hydration governs the time-dependent and nonlinear evolution of hydraulic conductivity, especially during the early ages. Moreover, a higher fiber content causes a larger hydraulic conductivity, while hydraulic conductivity shows a decreasing trend as fiber length increases. Furthermore, a predictive model was developed to estimate the hydraulic conductivity. The good agreement between predicted results and measured data indicates the proposed model can be used as a useful tool to evaluate the combined effect of fiber inclusion and cement hydration on the evolution of hydraulic conductivity of FR-CPB.