The Potential to Replace Cement with Nano‐Calcium Carbonate and Natural Pozzolans in Cemented Mine Backfill

Abstract

The effectiveness of mine backfilling depends on the properties of its constituents. The high cost of cement, which is commonly used as a binder in mine backfill, has led researchers to seek alternatives to partially replace it with other binders. This study investigated the potential to use nano-calcium carbonate (NCC) and natural pozzolans (zeolite and pumice) along with Portland cement (PC) in mine backfill. Two types of experimental samples were prepared: (1) gold tailings and silica sand to investigate the effect of NCC and (2) nickel tailings to investigate the effect of natural pozzolans. The unconfined compressive strength (UCS) was measured for samples cured for up to 56 days. Moreover, selected samples were subject to mercury intrusion porosimetry to investigate microstructural properties. Results show that addition of NCC did not improve the UCS of backfill prepared with gold tailings and cured for 28 days, whereas a dosage of 1% NCC in backfill samples prepared with silica sand improved UCS by 20%, suggesting that the gold tailings negatively affected strength development. Natural pozzolans, in particular, 20% zeolite, had 24% higher UCS after 56 days of curing compared to samples prepared with PC and thus have the potential to partially replace cement in mine backfill.

Characterization of Strength and Quality of Cemented Mine Backfill Made up of Lead-Zinc Processing Tailings

“…While the creation of ettringite at early stages is linked with the use of added sulfates to avoid flash sets, its formation at later stages due to external sulfate attack or delayed ettringite formation can cause degradation of concrete structures (Gu et al, 2019). In mine backfill applications, the cement is often used to prevent the AMD formation, and also to offer the mechanical strength, which is critical for the stability of CPB (Hefni and Ali, 2021). To reduce/eliminate the negative effects of AMD which is harmful to vegetation, aquatic life, wildlife, groundwater, and strength of mine backfill (Li et al, 2020;Wang et al, 2021), many researchers have studied to reduce the amount of the cement needed by using different types of cement and additives (Xue et al, 2020;Yan et al, 2020;Huan et al, 2021).…”

The Application of Nano-Calcium Carbonate in the Technology of Improving Road Petroleum Asphalt

“…De Almeida [28] established a mesomechanics analytical model that is simple, easy to program, and calculates for composite materials with spring-type interfaces and interlayer interfaces, which is used to predict the effective elastic properties of composite materials with weak interfaces. e following will describe the model established by Hefni and Ali and use it to predict the effect of MWCNT [29] doping on Liqing and milk green mixtures.…”

Movement and deformation characteristics of overlying stratum in paste composite filling stope

“…Compared with the caving method, the stope is affected by the filling body, and a new dynamic space of “support-surrounding rock (working face coal body, roof, floor)—composite filling body” is formed in the stope. In the method, new characteristics can be found for the stress state, movement, deformation and failure law of overlying stratum (Al Heib et al, 2010; Yilmaz et al, 2014; Kostecki and Spearing, 2015; Ke et al, 2016; Hefni and Ali, 2021; Huang et al, 2021). There will be a part of the roof on the side of the coal wall in a suspended roof state in the process of working face advancement through field test and physical similarity simulation experiments, and a mechanical model of overlying rock movement change is established, such as Figure 2, the working face advances from left to right, x = 0 is the opening of the working face, and the empty area is filled from this position, x = L is the position of the working face coal wall.…”