Witteman, M & Simms, P 2010, 'Hydraulic response in cemented paste backfill during and after hydration', in R Jewell & AB Fourie (eds), Proceedings of the Thirteenth International Seminar on Paste and Thickened Tailings
, Australian Centre for Geomechanics, Perth, pp. 199-207.
The distribution of pore-pressures in mine stopes may have important implications to the design of cemented
paste backfill (CPB) systems. Self-weight consolidation after filling stopes is inherently problematic when
pore-water pressures begin to develop. However, during cement hydration, self-desiccation begins to occur
and consequently, pore-water pressures gradually dissipate. In some cases, during self-desiccation, matric
suctions can develop within stopes, depending upon adopted mining strategies such as, fill rate and percent
water to binder content. Tracking the evolution and quantifying the hydraulic behaviour in cemented paste is
rather difficult because of the complexity of the hydrating material. The current study investigates and
attempts to capture CPB’s transient responses during and after cement hydration through a series of self-
desiccation tests and axis translation tests. Self-desiccation tests are conducted on cemented paste specimens
containing 0, 3, 5 and 7% wt binder material. The water-retention properties of the material are measured
without binder, and after 28 days of hydration. This data is then used to approximately model the dissipation
of pore-water pressures measured at the bottom of stope during a plug pour. The approach shows promise.
Significance and future improvement to the proposed methodology are discussed.
Acker, P. (2004) Swelling, shrinking and creep: a mechanical approach to cement hydration, Materials and
Structures/Concrete Science and Engineering, 37, pp. 237–243.
Belem, T., Bussiere, B. and Benzaazoua, M. (2001) The effect of microstructural evolution on the physical properties of
paste backfill, In Proceedings Tailing and Mine Waste 2001, A.A. Balkema, pp. 365–374.
Belem, T., Harvey, A., Simon, R. and Aubertin, M. (2004) Measurement and prediction of internal stresses in an
underground opening during its filling with cemented fill, In Proceedings 5th International Symposium on
Ground Support in Mining and Underground Construction, pp. 619–630.
Belem, T. and Benzaazoua, M. (2008) Design and application of underground mine paste backfill technology,
Geotechnical and Geological Engineering, Vol. 26(2008), pp. 147–174.
Decagon Devices Inc. (2007) Operator’s manual for models WP4 and WP4-T, Dewpoint PotentiaMeter.
Fourie, A., Helinski, M. and Fahey, M. (2006) Filling the gap – a geomechanics perspective, Australian Centre for
Geomechanics, Perth, Australia, Newsletter 26, pp. 1–4.
Grabinsky, M. and Simms, P. (2006) Self-desiccation of cemented paste backfill and implications for mine design, In
Proceedings Ninth International Seminar on Paste and Thickened Tailings, Australian Centre for Geomechanics,
Perth, Australia, pp. 323–336.
Grabinsky, M. and Bawden, W.F. (2007) In situ measurements of geomechanical design of cemented paste backfill
systems, In Proceedings Minefill 2007 (Paper No. 2456), [CD-ROM].
Helinski, M., Fourie, M., Fahey, M. and Ismail, M. (2007) Assessment of the self-desiccation process in cemented mine
backfills, Canadian Geotechnical Journal, Vol. 44, pp. 1148–1156.
Hilf, J.W. (1956) An investigation of pore-water pressure in compacted cohesive soil, Ph.D. thesis, Technical
Memorandum 654, U.S. Department of the Interior Bureau of Reclamation, Denver, Colorado.
Hua, C., Acker, P. and Ehrlacher, A. (1995) Analyses and models of the autogenous shrinkage of hardening cement
paste, Cement and Concrete Research, Vol. 25(7), pp. 1457–1468.
Kim, J-K. and Lee, C-S. (1999) Moisture diffusion of concrete considering self-desiccation at early ages, Cement and
Concrete Research, Vol. 29, pp. 1921–1927.
le Roux, K. (2004) In situ properties and liquefaction potential of cemented paste backfill, PhD thesis, Graduate
department of civil engineering, University of Toronto, Canada.
Li, L., Aubertin, M. and Belem, T. (2005) Formulation of a three dimensional analytical solution to evaluate stresses in
backfilled vertical narrow openings, Canadian Geotechnical Journal, Vol. 42, pp. 1705–1717.
Simms, P. and Grabinsky, M. (2009) Direct measurement of matric suction in triaxial tests on early-age cemented paste
backfill, Canadian Geotechnical Journal, Vol. 46, pp. 93–101.
Umwelt-Monitoring-Systeme (UMS) (2009) User Manual: T5/T5x pressure transducer tensiometer, Ver 12/2009, UMS
Hydraulic response in cemented paste backfill during and after hydration M. Witteman and P. Simms
208 Paste 2010, Toronto, Canada