Coupled effect of cement hydration and temperature on hydraulic behavior of cemented tailings backfill

Abstract

Cemented tailings backfill (CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process can release significant amount of heat to raise the temperature of CTB and in turn increase the rate of cement hydration. Meanwhile, the progress of cement hydration consumes water and produces hydration products to change the pore structures within CTB, which further influences the hydraulic behavior of CTB. In order to understand the hydraulic behavior of CTB, a numerical model was developed by coupling the hydraulic, thermal and hydration equations. This model was then implemented into COMSOL Multiphysics to simulate the evolutions of temperature and water seepage flow within CTB versus curing time. The predicted outcomes were compared with correspondent experimental results, proving the validity and availability of this model. By taking advantage of the validated model, effects of various initial CTB and curing temperatures, cement content, and CTB’s geometric shapes on the hydraulic behavior of CTB were demonstrated numerically. The presented conclusions can contribute to preparing more environmentally friendly CTB structures.

Keywords

cemented tailings backfill / hydration / water seepage flow / pore water pressure / coupled model

References

[1] WuD, FallM, CaiS J. Coupling temperature, cement hydration and rheological behaviour of fresh cemented paste backfill [J]. Minerals Engineering, 2013, 42: 76-87

[2] ZhangQ L, HuG Y, WangX M. Hydraulic calculation of gravity transportation pipeline system for backfill slurry [J]. Journal of Central South University, 2008, 15(5): 645-649

[3] FallM, PokharelM. Coupled effects of sulphate and temperature on the strength of CPB [J]. Cement and Concrete Composites, 2010, 32(10): 819-28

[4] OrejarenaL, FallM. Mechanical response of a mine composite material to extreme heat load [J]. Bulletin of Engineering Geology and the Environment, 2007, 67(3): 387-396

[5] CihangirF, ErcikdiB, KesimalA, TuranA, DeveciH. Utilisation of alkali-activated blast furnace slag in paste backfill of high-sulphide mill tailings: Effect of binder type and dosage [J]. Minerals Engineering, 2012, 30: 33-43

[6] Abdul-HussainN, FallM. Unsaturated hydraulic properties of cemented tailings backfill that contains sodium silicate [J]. Engineering Geology, 2011, 123(4): 288-301

[7] PokharelM, FallM. Combined influence of sulphate and temperature on the saturated hydraulic conductivity of hardened cemented paste backfill [J]. Cement and Concrete Composites, 2013, 38: 21-28

[8] NasirO, FallM. Coupling binder hydration, temperature and compressive strength development of underground cemented paste backfill at early ages [J]. Tunnelling and Underground Space Technology, 2010, 25(1): 9-20

[9] FallM, AdrienD, CelestinJ C, PokharelM, ToureM. Saturated hydraulic conductivity of cemented paste backfill [J]. Minerals Engineering, 2009, 22(15): 1307-1317

[10] BentzD P. Three-dimensional computer simulation of Portland cement hydration and microstructure development [J]. Journal of the American Ceramic Society, 1997, 80: 3-21

[11] LeeH S, ChoT F. Hydraulic characteristics of rough fractures in linear flow under normal and shear load [J]. Rock Mechanics and Rock Engineering, 2002, 35(4): 299-318

[12] OlssonR, BartonN. An improved model for hydro-mechanical coupling during shearing of rock joints [J]. International Journal of Rock Mechanics and Mining Sciences, 2001, 38(3): 317-329

[13] NguyenT S, SelvaduraiA P S. Coupled thermal-hydrological-mechanical processes in sparsely fractured rock [J]. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1995, 32: 465-480

[14] XuL, WangX, XianX. Effects of temperature and pressure differences on water seepage in breccias [J]. Chinese Journal of Geochemistry, 2012, 31: 260-263

[15] ThomasH R, HeY, SansomM R, LiC L W. On the development of the thermo-mechanical-hydraulic behaviour of unsaturated soils [J]. Engineering Geology, 1996, 41: 197-218

[16] QianC, HuangB, WangY, WuM. Water seepage flow in concrete [J]. Construction and Building Materials, 2012, 35: 491-496

[17] SchindlerA K, FolliardK J. Heat of hydration models for cementitious materials [J]. ACI Materials Journal, 2005, 102(1): 24-33

[18] KjellsenK O, DetwilerR J, GjorvO E. Development of microstructure in plain cement pastes hydrated at different temperatures [J]. Cement and Concrete Research, 1991, 21(1): 179-189

[19] Abdul-hussainN, FallM. Thermo-hydro-mechanical behavior of sodium silicate-cemented paste tailings in column experiments [J]. Tunneling and Underground Space Technology, 2012, 29: 85-93

[20] SchindlerA K, FolliardK J. Influence of supplementary cementing materials on the heat of hydration of concrete [C]. 9th Conference on Advances in Cement and Concrete. Colorado, USA, 2003

[21] KimJ K, HanS H, LeeK M. Estimation of compressive strength by a new apparent activation energy function [J]. Cement and Concrete Research, 2001, 31: 217-225

[22] BourgeoisF, BurlionN, ShaoJ F. Modelling of elastoplastic damage in concrete due to desiccation shrinkage [J]. International Journal for Numerical an Analytical Methods in Geomechanics, 2002, 26(8): 759-774

[23] PoyetS, CharlesaS, HonoreN, LhostisaV. Assessment of the unsaturated water transport properties of an old concrete: Determination of the pore-interaction factor [J]. Cement and Concrete Research, 2011, 41(10): 1015-1023

[24] LucknerL, van GenuchtenM T H, NielsenD R. A consistent set of parametric models for the two-phase flow of immiscible fluids in the subsurface [J]. Water Resources Research, 1989, 25(10): 2187-2193

[25] TongF, JingL, ZimmermanR W. A fully coupled thermo-hydro-mechanical model for simulating multiphase flow, deformation and heat transfer in buffer material and rock masses [J]. International Journal of Rock Mechanics and Mining Sciences, 2010, 47(2): 205-217