Characterisation of Self-Weight Consolidated Paste Backfill

Authors: Belem, T; El Aatar, O; Bussiere, B; Benzaazoua, M; Fall, M; Yilmaz, E Download Paper

DOI https://doi.org/10.36487/ACG_repo/663_29

Cite As:
Belem, T, El Aatar, O, Bussiere, B, Benzaazoua, M, Fall, M & Yilmaz, E 2006, 'Characterisation of Self-Weight Consolidated Paste Backfill', in R Jewell, S Lawson & P Newman (eds), Paste 2006: Proceedings of the Ninth International Seminar on Paste and Thickened Tailings, Australian Centre for Geomechanics, Perth, pp. 333-345, https://doi.org/10.36487/ACG_repo/663_29



Abstract:
Recent studies showed that for a given mix recipe and curing time the unconfined compressive strength (UCS) of in situ paste backfill (PB) core samples can be 2 to 4 times higher than samples of the same PB mix poured into plastic moulds (Belem et al., 2002; le Roux et al., 2002; Cayouette, 2003; Revell, 2004). Also, the same observations were made for PB samples prepared and cured in laboratory conditions compared to in situ underground PB samples (Belem et al., 2000 and 2001). These differences in compressive strength could be attributed at least in part to the PB hardening (e.g. Benzaazoua et al., 2004) conditions in the stope such as: stope size and geometry, stope walls convergence against the fill mass and its resulting shrinkage (Belem et al., 2004). Other factors of influence are the amount of bleeding water and the gravity-driven consolidation settlement of the PB mass which may depend on its physico-geochemical properties and also on the physical properties of the surrounding rock mass. It was reported that this self-weight consolidation settlement can reach more than 1 m and is usually considered to positively affect the PB strength development (e.g. Belem et al., 2002; le Roux, 2002; Cayouette, 2003). A relatively large number of experimental studies are reported in the literature on the self-weight consolidation of granular slurries, debris, dredge materials or waste rock and mine tailings (e.g. Been and Sills, 1981; Wickland and Wilson, 2005). The originality of the present study, however, is that it considers high density slurry (solids mass concentration ranging from 70% to 85% w/w). To the knowledge of the authors, only very few investigations on the consolidation behaviour of PB have been completed to date (e.g. Belem et al., 2002; le Roux et al., 2002). The purpose of this paper is to characterize the physical and mechanical properties of PB prepared at Louvicourt mine paste backfill plant, poured and cured into 3 m high PVC/Makrolon® polycarbonate sheet settling columns following three scenarios: fully-drained (FD), half-drained (HD) and undrained (UD) conditions. The main objective is to better understand the effect of self-weight consolidation settlement of PB on its physical and mechanical properties.

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