Effect of specimen composition on the strength development in cemented paste backfill

Abstract

This paper focuses on monitoring setting and strength development in cemented paste backfill (CPB). The composition of the paste is altered to study the effects of binder type and content, selected chemical admixtures (superplasticizers), mineral additives (e.g., fly ash), and pore fluid chemistry (e.g., ionic concentration and pH) on these properties. The three main techniques utilized are shear wave velocity measurements, penetration tests (e.g., Vicat needle tests), and unconfined compressive strength tests. All of these tests are sensitive to changes in the paste composition. The effect of the pore fluid chemistry and the chemical additives on the CPB properties depends on the ion type and concentration and the chemical composition of the superplasticizers. The shear wave velocity in both uncemented and cemented pastes increases with time as a result of self-weight consolidation, capillary forces, and cementation (the precipitation of ions in uncemented tailings pastes or cement hydration in cemented tailings pastes).Résumé : Cet article se concentre sur le montage d'instrumentation et sur le développement de la résistance dans un remblai de pâte-ciment (CPB). La composition de la pâte est modifiée pour étudier les effets sur ses propriétés du type et de la teneur du liant, des mélanges chimiques sélectionnés (superplastifiants), des additifs minéraux (e.g., cendres volantes), et de la chimie du fluide interstitiel (e.g., concentration ionique et pH). Les trois principales techniques utilisées sont les ondes de cisaillement, les essais de pénétration (e.g., essais à l'aiguille Vicat) et les essais de résistance en compression simple. Tous ces essais sont sensibles aux changements dans la composition de la pâte. L'effet de la chimie du fluide interstitiel et des additifs chimiques sur les propriétés du CPB dépend du type et de la concentration d'ions, et de la composition chimique des superplastifiants. La vitesse des ondes de cisaillement tant dans les pâtes cimentées que non cimentées augmente avec le temps à cause de la consolidation sous son propre poids, des forces capillaires et de la cimentation (la précipitation des ions dans les pâtes de stériles non cimentées ou l'hydratation du ciment dans les pâtes de stériles cimentées).Mots clés : remblai de pâte-ciment, vitesse des ondes de cisaillement, montage, résistance en compression simple.[Traduit par la Rédaction] Klein and Simon 324

Rational Utilization of Fine Unclassified Tailings and Activated Blast Furnace Slag with High Calcium

“…After sampling, the drying [19] of unclassified tailings was carried out under standard conditions, before being kept in a safe space (Figure 1). It is known that the physicochemical properties of unclassified tailings play an important role in the application of CPB [9][10][11]. Hence, the chemical composition was measured by the titrimetric method and particle size distribution was tested by one laser particle size analyzer (Malvern Instruments Ltd., Malvern, UK), which was conducted in Chemical Composition Analysis Center, Central South University.…”

“…Filling the goafs with tailings seems to be an ideal solution [5], with cemented paste backfill (CPB) being widely and intensively employed in the global mining industry [6][7][8]. The physicochemical properties of unclassified tailings play an important role in the application of CPB [9][10][11], such as strength, hardening performance and pipeline transportation. Having a large proportion of fine particles makes it difficult to harden the tailings backfill body.…”

Hydraulic Conductivity of Fly Ash-Amended Mine Tailings

“…The mechanical, hydraulic, and environmental behavior of CPB has been investigated by numerous researchers (Landriault et al 1997;Zou and Li 1999;Belem et al 2000;Belem et al 2001;Benzaazoua et al 2004;Fall et al 2005Fall et al , 2008Kesimal et al 2005;Klein and Simon 2006;Ouellet et al 2006;Ouellet et al 2007;Benzaazoua et al 2008;Ercikidi et al 2009;Yeheyis et al 2009;Nasir and Fall 2010;Zhang et al 2011;Ercikidi et al 2013). In general, addition of a cementitious binder has been shown to increase strength, reduce hydraulic conductivity, increase pH of the effluent, and stabilize heavy metals present in mine tailings.…”

An Investigation of the Uniaxial Compressive Strength of a Cemented Hydraulic Backfill Made of Alluvial Sand

“…Knowing that the strength of cemented backfill depends on several influencing factors that include binder content, solid (tailings or/and sand) percentage, water content, and curing time, determination of an optimal recipe may depend on the target (shorter curing time versus lower cement consumption) and require a lot of laboratory tests [14][15][16][17][18][19][20][21][22][23].…”