Ultra rapid strength development in dry-mix shotcrete for ultra rapid support in challenging mining conditions

Authors: Lemay, J-D; Jolin, M; Gagné, R Download Paper

DOI https://doi.org/10.36487/ACG_rep/1410_17_Lemay

Cite As:
Lemay, J-D, Jolin, M & Gagné, R 2014, 'Ultra rapid strength development in dry-mix shotcrete for ultra rapid support in challenging mining conditions', in M Hudyma & Y Potvin (eds), Deep Mining 2014: Proceedings of the Seventh International Conference on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 271-279, https://doi.org/10.36487/ACG_rep/1410_17_Lemay



Abstract:
Recent development in the field of cementing materials has brought forward many non-traditional binder systems. Engineers involved in the fields of emergency repairs and rapid ground support have been on the lookout for materials that allow rapid production, placement and, most of all, very rapid strength development kinetics. One binder system that fits the description is composed of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and calcium sulfate (C$). However, this type of binder also sometimes exhibits difficult workability that severely limits its use in regular cast in-place concrete. This limitation is overcome when using dry-mix shotcrete as a placement method, since the contact between water and cement occurs in the nozzle immediately before placement, workability problem are avoided. As a part of a graduate project at Laval University, 49 different mixes, including simple, binary and (mainly) ternary blends, were tested. Two majors parameters were studied, the development of compressive strength and the volumetric stability. The numerous binder compositions tested allowed the selection of a stable optimised formulation in regard of early compressive strength and volumetric stability. Finally, the selected formulation was successfully tested with industrial dry-mix shotcrete equipment to verify the large scale placement feasibility of such a product.

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