Synthesis and characterization of fly ash geopolymer paste for goaf backfill: Reuse of soda residue

Zhao, Xianhui; Liu, Chunyuan; Zuo, Liming; Li, Wang; Zhu, Qin; Liu, Youcai; Zhou, Boyu

doi:10.1016/j.jclepro.2020.121045

Cited by 88 publications

(110 citation statements)

References 56 publications

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“…Furthermore, the 7 d UCS of the SR-FFA-NS system pastes with initial Ca/Si ratio 1.0 is gradually decreasing with 35.55~53.59% of water content, and while the fluidity is increasing with the increase of water contents (Figure 2d), the changing laws of which are consistent with that of widely used cement based slurry [24]. Therefore, when the initial Ca/Si ratio is 1.0, the paste can still be adjusted to meet the property requirement of backfill grouting material (close to/higher than 200 mm in fluidity, and higher than 0.6 MPa in 7 d and 28 d UCS [19,23]) by changing the water content.…”

Section: The Proposed Bhg Alternative To Nssupporting

confidence: 74%

“…The reaction mechanisms of C-S-H gels were expressed as the following formulae (1), (2) and (3). n refers to any reaction coefficient [24]. In particular, the properties of C-S-H gels are closely related to its initial Ca/Si ratios in raw materials.…”

Section: Influence Of Initial Ca/si Ratios On Fluidity and 7 D Unconfmentioning

confidence: 99%

“…Therefore, it is significant to explore another activator alternative to NS to prepare the SR-FFA based geopolymer backfill paste. In a previous study, the C-S-H gels generated in SR-FFA-NS system pastes produced cementation to determine the early strength [24]. If the effective components CaCl 2 , Ca(OH) 2 and CaSO 4 in SR react with NS at the initial Ca/Si ratio of 1.0, it leads to the highest contents of C-S-H gels and the highest values of 7 d UCS.…”

Section: The Proposed Bhg Alternative To Nsmentioning

confidence: 99%

“…The FTIR tests were used to further study the reaction changes in chemical bonds for control and backfill paste. In the previous study, the FTIR spectra and 29 Si nuclear magnetic resonance (NMR) pattern of SR, FFA, control S100NS and paste S2F3NS were tested to detect the gel products ( Figure 6a) in the reference [24]. Here, the FTIR spectra of control SN5, control C0 and paste C4 at 7 d and 28 d were measured to clarify the effects of BHG on the gel products in chemical bonds, and verify the correctness of the reaction mechanism, as shown in Figure 6b.…”

Section: Chemical Bonds Analysis For Gel Product Through Fourier Tranmentioning

confidence: 99%

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Performance Optimization and Characterization of Soda Residue-Fly Ash Geopolymer Paste for Goaf Backfill: Beta-Hemihydrate Gypsum Alternative to Sodium Silicate

et al. 2020

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Solid waste soda residue (SR), as an industrial pollutant of water, air and soil environment, can be utilized to prepare the low-calcium fly ash (FFA)-based geopolymer paste activated by sodium silicate (NS) solution for goaf backfill. However, the high addition of NS produces the high cost and high strength of synthesized backfill material in the previous study. The objective of this research is to investigate the cost optimization method and performance evaluation of SR-FFA-based geopolymer backfill paste. The alkaline beta-hemihydrate gypsum (BHG) alternative to partial NS was proposed. Scanning electron microscopy (SEM), X-ray diffraction (XRD) as well as Fourier transform infrared spectrometer (FTIR) tests were performed to clarify the role of BHG and evaluate the microstructures and products of backfill pastes. The results show that 10% BHG alternative ratios effectively improve fluidity, setting time and compressive strength to satisfy the performance requirement of goaf backfill material. The gel products in the optimal backfill paste C4 with 10% BHG alternative ratios are determined as the coexistence of C-S-H gel, (N,C)-A-S-H gel and CaSO4·2H2O at 28 d. The research results can make extensive utilization of SR and FFA in cemented paste backfill to synthesize cleaner material at a larger scale.

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Section: The Proposed Bhg Alternative To Nssupporting

confidence: 74%

Section: Influence Of Initial Ca/si Ratios On Fluidity and 7 D Unconfmentioning

confidence: 99%

Section: The Proposed Bhg Alternative To Nsmentioning

confidence: 99%

Section: Chemical Bonds Analysis For Gel Product Through Fourier Tranmentioning

confidence: 99%

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Performance Optimization and Characterization of Soda Residue-Fly Ash Geopolymer Paste for Goaf Backfill: Beta-Hemihydrate Gypsum Alternative to Sodium Silicate

et al. 2020

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“…It is estimated that the synthesis of Portland cement is twice as energy-intensive as the production of geopolymers and causes 4 to 8 times more carbon dioxide emission (Provis and van Deventer 2009). According to several authors (Bajpai et al 2020;Zhao et al 2020), using geopolymers as a substitute for Portland cement reduces the environmental load significantly.…”

Section: Introductionmentioning

confidence: 99%

Analysis of an application possibility of geopolymer materials as thermal backfill for underground power cable system

Ocłoń

Cisek

Matysiak

2020

Clean Techn Environ Policy

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The circular economy is a closed cycle that allows one to reuse the industrial waste, as well as minimize the energy and resources losses during the production process. This paper presents an innovative idea of the application of a geopolymer cable backfill for underground power cable system installation. The closed cycle, in this case, is formulated as follows: the primary resource is the waste from the combustion of fossil fuels, i.e., fly ash that is utilized to form the geopolymer matrix. The geopolymer then is used as thermal backfill in underground power cable systems. Utilization of combustion by-products in the form of a geopolymer is a highly profitable solution since landfill waste disposal, in this case, generates considerable costs for the electrical energy producers. In typical applications, geopolymers are used as insulators. By adding individual components, the thermal conductivity of 2.0 W/(m K), higher than of typical thermal backfills (Fluidized Thermal Backfill), which value is close to 1.5 W/(m K), is reached. What is very important, geopolymers can absorb water better than typical sand–cement mixtures. As a result, a high thermal conductivity with the temperature increase is maintained. The application of geopolymers as thermal backfills has the potential to improve the flexibility of underground power cable systems, as well as to minimize the material costs of installation. The case study is presented to show the economic benefits of using the combustion by-products as a geopolymer thermal backfill. The finite element method model of an underground power cable system is developed, and optimization of backfill dimensions is provided to minimize the material costs using the geopolymer thermal backfill and to maximize the underground power cable system performance. The main result of this paper is that the application of geopolymers leads to a decrease in underground power cable system costs, compared to traditional backfill (sand–cement mixture). The reason is the higher value of thermal conductivity, which allows selecting a cable with a smaller cross-sectional area. Also, the environmental benefits of geopolymer application for cable bedding are discussed. Graphic abstract

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Study on the Unconfined Compressive Strength Property and Mechanism of Soda Residue Soil

Zhao,

Yang,

et al. 2024

Geotech Geol Eng

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Synthesis and characterization of fly ash geopolymer paste for goaf backfill: Reuse of soda residue

Cited by 88 publications

References 56 publications

Performance Optimization and Characterization of Soda Residue-Fly Ash Geopolymer Paste for Goaf Backfill: Beta-Hemihydrate Gypsum Alternative to Sodium Silicate

Performance Optimization and Characterization of Soda Residue-Fly Ash Geopolymer Paste for Goaf Backfill: Beta-Hemihydrate Gypsum Alternative to Sodium Silicate

Analysis of an application possibility of geopolymer materials as thermal backfill for underground power cable system

Study on the Unconfined Compressive Strength Property and Mechanism of Soda Residue Soil

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