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As the main components of Portland cement, calcium silicates show substantial differences in their hydration reactivity which have not been fully explained. A comprehensive comparison of the initial hydration process of calcium silicates, namely dicalcium silicate (C2S) and tricalcium silicate (C3S), was conducted using molecular dynamics simulations. The initial hydration process was divided into three stages using cut-off times of 0.001 ns and 3 ns. The hydration of M3-C3S (010) was more evident than that of β-C2S (100), supported by the hydroxylation degree, radial distribution function, atomic density profile, etc. The coordination number of the surface Ca atoms might be the underlying reason for such a difference. Interactions between cement surfaces and water molecules were mainly characterised by solid OH bonding and Ca-water O bonding. Dissolution of Ca atoms was observed, although quite scarce, while no dissolution of Si atoms was observed.
Chongchong Qi; Hegoi Manzano; Dino Spagnoli; QiuSong Chen; Andy Fourie. Initial hydration process of calcium silicates in Portland cement: A comprehensive comparison from molecular dynamics simulations. Cement and Concrete Research 2021, 149, 106576 .
AMA StyleChongchong Qi, Hegoi Manzano, Dino Spagnoli, QiuSong Chen, Andy Fourie. Initial hydration process of calcium silicates in Portland cement: A comprehensive comparison from molecular dynamics simulations. Cement and Concrete Research. 2021; 149 ():106576.
Chicago/Turabian StyleChongchong Qi; Hegoi Manzano; Dino Spagnoli; QiuSong Chen; Andy Fourie. 2021. "Initial hydration process of calcium silicates in Portland cement: A comprehensive comparison from molecular dynamics simulations." Cement and Concrete Research 149, no. : 106576.
Current design methods for underground structures surrounded by jointed rock masses fail to account for the deformational characteristics of these surrounding rock masses, employing only input parameters that are defined prior to construction. Thus, there is the need to investigate the effects on underground structures that result from the deformational characteristics of jointed rocks that undergo stress relaxation during their excavation. Comprehensive research is conducted in this study. First, we propose an equivalent stress- and strain-dependent model incorporating equivalent stiffness at small strains into a hyperbolic model from intermediate to large strains. Then, experimental tests are conducted to characterize the deformational characteristics of jointed rock masses and extract requisite model parameters such as joint properties and nonlinearity. Finally, two numerical simulations are conducted using the proposed model to determine its field applicability to an unlined circular tunnel. The nonlinear simulation results are compared with the conventional analysis method that uses a constant stiffness value. Our results show that the proposed equivalent jointed rock mass model, which considers stress-and strain-dependency, can be utilized for deformational analysis of underground structures involving excavations in jointed rocks.
Song-Hun Chong; Ki-Il Song; Gye-Chun Cho. Development of Equivalent Stress- and Strain- Dependent Model for Jointed Rock Mass and Its Application to Underground Structure. KSCE Journal of Civil Engineering 2021, 1 -10.
AMA StyleSong-Hun Chong, Ki-Il Song, Gye-Chun Cho. Development of Equivalent Stress- and Strain- Dependent Model for Jointed Rock Mass and Its Application to Underground Structure. KSCE Journal of Civil Engineering. 2021; ():1-10.
Chicago/Turabian StyleSong-Hun Chong; Ki-Il Song; Gye-Chun Cho. 2021. "Development of Equivalent Stress- and Strain- Dependent Model for Jointed Rock Mass and Its Application to Underground Structure." KSCE Journal of Civil Engineering , no. : 1-10.
Anionic polyacrylamide (APAM) has widely been employed in backfill mining to accelerate the sedimentation of fine tailings particles and increase the concentration of tailings slurry. However, APAM inevitably remains in thickened tailings, leading to a nonnegligible influence on the rheological, mechanical, and heavy metal leaching properties of tailings-based cemented paste backfill (CPB). In an effort to solve these issues, the influences of APAM on CPB properties were examined in the present study. Experimental tests such as rheology, uniaxial compressive strength (UCS), toxicity leaching, and microscopy were conducted. The results showed that the presence of APAM first significantly increased the yield stress and viscosity of CPB slurry. APAM slightly improved the early UCS of CPB curing for 7 days but hindered the UCS development of samples cured for 28 days. Moreover, the presence of APAM restrained the hydration reaction, reduced the amounts of hydrated products, increased pore size, and loosed the microstructure of the test samples. Finally, the addition of APAM effectively reduced the leaching of Ag and As, while incremented that of Cu and slightly affected the leaching of Ba. In sum, these findings look promising for the safe production and environmental protection of the mining industry.
QiuSong Chen; Yunbo Tao; Qinli Zhang; Chongchong Qi. The rheological, mechanical and heavy metal leaching properties of cemented paste backfill under the influence of anionic polyacrylamide. Chemosphere 2021, 286, 131630 .
AMA StyleQiuSong Chen, Yunbo Tao, Qinli Zhang, Chongchong Qi. The rheological, mechanical and heavy metal leaching properties of cemented paste backfill under the influence of anionic polyacrylamide. Chemosphere. 2021; 286 (Pt 1):131630.
Chicago/Turabian StyleQiuSong Chen; Yunbo Tao; Qinli Zhang; Chongchong Qi. 2021. "The rheological, mechanical and heavy metal leaching properties of cemented paste backfill under the influence of anionic polyacrylamide." Chemosphere 286, no. Pt 1: 131630.
PM2.5 is a major pollutant in the ambient air of open-pit mining, whose accurate prediction is significant for its removal and control design. In this study, a hybrid method was proposed for analyzing PM2.5 concentration. A field measurement of PM2.5 concentration was conducted at an operating open-pit mine in northern China. The data was cleaned to remove the outliers in the PM2.5 results. Gradient boosting machine (GBM) optimized by particle swarm optimization (PSO) was used for the regression and classification analysis. In terms of regression, different scenarios were designed to evaluate the effect of time interval for future predictions (5 min, 10 min, 20 min, 40 min, 1 h, and 2 h ahead) on the performance. The classification of PM2.5 concentration into ‘severe’ and ‘not severe’ was also analysed. The results are as follows: (i) A total of 37 data instances were detected to be outliers, and the regression performance was improved after data cleaning (from 0.902 to 0.937 on the training set and from 0.877 to 0.940 on the testing set). (ii) The percentage of training set percentage was determined to be 70%, and PSO performed well in optimizing the hyper-parameters of GBM, (iii) The regression was quite satisfactory with the correlation coefficient being larger than 0.9. The testing performance decreased with the increase in time interval. (iv) An average accuracy of 0.954 was achieved during the classification of PM2.5 concentration. The predicted PM2.5 concentration could work as a precursor for the heavy PM pollution around open-pit mining.
Xiang Lu; Wei Zhou; Chongchong Qi; Huaiting Luo; Dongxu Zhang; Binh Thai Pham. Prediction into the future: A novel intelligent approach for PM2.5 forecasting in the ambient air of open-pit mining. Atmospheric Pollution Research 2021, 12, 101084 .
AMA StyleXiang Lu, Wei Zhou, Chongchong Qi, Huaiting Luo, Dongxu Zhang, Binh Thai Pham. Prediction into the future: A novel intelligent approach for PM2.5 forecasting in the ambient air of open-pit mining. Atmospheric Pollution Research. 2021; 12 (6):101084.
Chicago/Turabian StyleXiang Lu; Wei Zhou; Chongchong Qi; Huaiting Luo; Dongxu Zhang; Binh Thai Pham. 2021. "Prediction into the future: A novel intelligent approach for PM2.5 forecasting in the ambient air of open-pit mining." Atmospheric Pollution Research 12, no. 6: 101084.
With the increasing use of the tunnel boring machine (TBM), attempts have been made to predict TBM operating parameters. Prediction of operating parameters is still an important step in the adaptability of the TBM for the future. In this study, we employ a walk forward (WF) prediction method based on ARIMAX, which can consider time-varying features and geological conditions. This method is applied to two different TBM projects to evaluate its performance, and is then compared with WF based on ordinary least squares (OLS). The simulation results show that the ARIMAX predictor outperforms the OLS predictor in both projects. For practical applications, an additional analysis is carried out according to the real-time prediction distance. The results show that time series-based ARIMAX provides meaningful results in 8 rings (11 m) or less of real-time prediction distance. The WF based on ARIMAX can provide reasonable TBM operating conditions with time-varying data and can be utilized in decision-making to improve excavation performance.
Hang-Lo Lee; Ki-Il Song; Chongchong Qi; Jin-Seop Kim; Kyoung-Su Kim. Real-Time Prediction of Operating Parameter of TBM during Tunneling. Applied Sciences 2021, 11, 2967 .
AMA StyleHang-Lo Lee, Ki-Il Song, Chongchong Qi, Jin-Seop Kim, Kyoung-Su Kim. Real-Time Prediction of Operating Parameter of TBM during Tunneling. Applied Sciences. 2021; 11 (7):2967.
Chicago/Turabian StyleHang-Lo Lee; Ki-Il Song; Chongchong Qi; Jin-Seop Kim; Kyoung-Su Kim. 2021. "Real-Time Prediction of Operating Parameter of TBM during Tunneling." Applied Sciences 11, no. 7: 2967.
The cemented paste backfill (CPB) technology has matured as a promising way for tailings recycling in the mining industry. Nevertheless, the current CPB design requires a large number of lab experiments to determine the unconfined compressive strength (UCS) of CPB. The utilisation of artificial intelligence (AI) prediction to reduce the lab experiments has been attempted without reaching its full potential. In this study, a hybrid model based on adaptive neuro fuzzy inference system (ANFIS) and artificial bee colony (ABC) was used for performance improvement. The ANFIS was used to learn the relationship between inputs and UCS while the ABC algorithm was used to tune the parameters of the initial ANFIS. The convergence of the prediction performance was tested using Monte Carlo simulations. A comparison between this study and previous studies was conducted and a sensitivity analysis was performed to investigate the importance of input variables. The results show that the ABC algorithm was efficient in tunning parameters of the ANFIS model. The representative ANFIS-ABC model yielded an R2 of 0.967 on the training part and an R2 of 0.976 on the testing part, indicating an excellent prediction. 310 Monte Carlo simulations were needed before a stable performance was achieved for all quality assessment criteria. The proposed hybrid model outperformed AI models in the literature (R2 was increased from 0.83/0.958/0.86 to 0.976 on the testing set). Solid content, cement-tailings ratio and curing time were found to be the most significant input parameters for the UCS of CPB.
Chongchong Qi; Hai-Bang Ly; Lu Minh Le; Xingyu Yang; Li Guo; Binh Thai Pham. Improved strength prediction of cemented paste backfill using a novel model based on adaptive neuro fuzzy inference system and artificial bee colony. Construction and Building Materials 2021, 284, 122857 .
AMA StyleChongchong Qi, Hai-Bang Ly, Lu Minh Le, Xingyu Yang, Li Guo, Binh Thai Pham. Improved strength prediction of cemented paste backfill using a novel model based on adaptive neuro fuzzy inference system and artificial bee colony. Construction and Building Materials. 2021; 284 ():122857.
Chicago/Turabian StyleChongchong Qi; Hai-Bang Ly; Lu Minh Le; Xingyu Yang; Li Guo; Binh Thai Pham. 2021. "Improved strength prediction of cemented paste backfill using a novel model based on adaptive neuro fuzzy inference system and artificial bee colony." Construction and Building Materials 284, no. : 122857.
For the cases where shallow foundation cannot satisfy the requirement of the foundation, engineers choose deep foundations without careful consideration of the cost-effectiveness. However, the bearing capacity of deep foundation is much bigger than shallow foundation. In this study, innovative shallow foundation type is introduced to increase the bearing capacity: The walls are attached to the base-slab of shallow foundation. To validate the performance of suggested shallow foundation, model tests were performed. Three different models (plate-, table-, and box-wall shaped foundations) are constructed in a small and large chamber, respectively. In the small chamber tests, the effect of degree of compaction (40, 60 and 80%) and footing width and wall length ratio (0.2, 0.4, 0.6, 0.8 and 1) on bearing capacity are evaluated. In large chamber test, the performance of wall-shaped foundation with respect to ultimate bearing capacity is evaluated. From the model tests, it is found that box-wall shaped foundation can increase the bearing capacity than table- and plate-wall shaped foundation. Also, the ultimate bearing capacities of box-wall shaped foundation are about 1.8 times than that of shallow foundation without wall.
Jung-Geun Hwang; Yeo-Won Yoon; Ki-Il Song. Improvement of Bearing Capacity of Shallow Foundation with the Wall Attached to the Base-Slab: Model Test. KSCE Journal of Civil Engineering 2021, 25, 1276 -1282.
AMA StyleJung-Geun Hwang, Yeo-Won Yoon, Ki-Il Song. Improvement of Bearing Capacity of Shallow Foundation with the Wall Attached to the Base-Slab: Model Test. KSCE Journal of Civil Engineering. 2021; 25 (4):1276-1282.
Chicago/Turabian StyleJung-Geun Hwang; Yeo-Won Yoon; Ki-Il Song. 2021. "Improvement of Bearing Capacity of Shallow Foundation with the Wall Attached to the Base-Slab: Model Test." KSCE Journal of Civil Engineering 25, no. 4: 1276-1282.
Estimation of pressure drops of fresh cemented paste backfill slurry is a novel idea with great potentials. This paper presented a hybrid machine learning (ML) method for improved pressure drops estimation using a combination of artificial neural network and differential evolution. A comprehensive parametric study was conducted on training dataset size (Nsize), ML methods, and Monte Carlo random sampling. Moreover, dependent analysis of pressure drops to each influencing variable was performed. The results indicate that 300 Monte Carlo realizations were sufficient for the converged and reliable results. The optimum Nsize was determined to be 70%, and the proposed hybrid method outperformed six individual ML methods. The estimation performance has been significantly improved compared to the methods used in the literature (R2 increased from 0.83 to 0.95 on the testing dataset). Solids content, inlet velocity, SiO2, CaO, and Fe2O3 were determined to be the most significant variables for pressure drops.
Chongchong Qi; Li Guo; Hai-Bang Ly; Hiep Van Le; Binh Thai Pham. Improving pressure drops estimation of fresh cemented paste backfill slurry using a hybrid machine learning method. Minerals Engineering 2021, 163, 106790 .
AMA StyleChongchong Qi, Li Guo, Hai-Bang Ly, Hiep Van Le, Binh Thai Pham. Improving pressure drops estimation of fresh cemented paste backfill slurry using a hybrid machine learning method. Minerals Engineering. 2021; 163 ():106790.
Chicago/Turabian StyleChongchong Qi; Li Guo; Hai-Bang Ly; Hiep Van Le; Binh Thai Pham. 2021. "Improving pressure drops estimation of fresh cemented paste backfill slurry using a hybrid machine learning method." Minerals Engineering 163, no. : 106790.
In order to reveal the hydration reaction of cemented paste backfill (CPB) more comprehensively, the non-contact electrical resistivity (NER) and microcalorimeter (TAM Air) were used to combine the hydration reaction with microstructure evolution of CPB in the early-age hydration process. The influence of tailings-cement ratio (TCR) on hydration reaction and microstructure evolution of CPB was studied, and the mathematical relationship model of resistivity and hydration heat of CPB was established; the kinetic parameters of CPB in the deceleration period were quantified by using the kinetic model; In combination with CPB’s unconfined compressive strength (UCS), the relationship between resistivity, hydration heat and UCS was established. The results show that the hydration process of resistivity and hydration heat characterization is highly consistent, which can be combined to characterize the hydration reaction and microstructure evolution of the CPB hydration process, and more comprehensively reveal the hydration reaction of CPB from a different perspective. Under different TCRs, the resistivity of CPB is affected by both tailings and cement. The content of tailings determines the overall value of its resistivity. As the content of tailings increases, the resistivity value increases, and the resistivity corresponds to the structural kinetic parameter Kc increases; the hydration heat of CPB is mainly affected by the cement content. The higher the cement content, the higher the hydration heat, and the larger the corresponding hydration kinetic parameter Km. In addition, the hydration reaction process characterized by resistivity and hydration heat is dominated by cement content, the specific manifestation is that as the cement content decreases, the induction period will be prolonged, the acceleration period and the deceleration period will be shortened, and the reaction constants D and D′ increase. The mathematical relation model of resistivity and accumulative heat release of CPB can realize the mutual characterization of resistivity and hydration heat.The resistivity and hydration heat of CPB under different TCR at 24, 36 and 48 h have good corresponding relationship with the UCS; the UCS of different TCRs at 28 days is negatively correlated with its resistivity at 48 h, and positively correlated with the hydration heat of 48 h. Studies have shown that the combination of resistivity and hydration heat can more fully reveal the hydration reaction and microstructure evolution of CPB, which is of great significance to the design of CPB.
Lang Liu; Pan Yang; Bo Zhang; Chao Huan; Lijie Guo; Qixing Yang; Ki-Il Song. Study on hydration reaction and structure evolution of cemented paste backfill in early-age based on resistivity and hydration heat. Construction and Building Materials 2020, 272, 121827 .
AMA StyleLang Liu, Pan Yang, Bo Zhang, Chao Huan, Lijie Guo, Qixing Yang, Ki-Il Song. Study on hydration reaction and structure evolution of cemented paste backfill in early-age based on resistivity and hydration heat. Construction and Building Materials. 2020; 272 ():121827.
Chicago/Turabian StyleLang Liu; Pan Yang; Bo Zhang; Chao Huan; Lijie Guo; Qixing Yang; Ki-Il Song. 2020. "Study on hydration reaction and structure evolution of cemented paste backfill in early-age based on resistivity and hydration heat." Construction and Building Materials 272, no. : 121827.
The aim of this paper is to propose a closed-form solution to the poromechanics problem of stress and pore pressure distribution around noncircular openings at great depth subjected to hydrostatic water pressure and far-field geostresses. The problem is solved by superposing the effects of fluid and solid skeleton obtained over simple circular geometries and generalizing the obtained expression to various geometries of mined ore bodies using complex variable functions and conformal mapping techniques. The principal stresses obtained analytically over the opening boundary and within the domain are compared with the results of finite-element analysis to verify the proposed approach. The comparison conducted for a representative noncircular opening indicates good agreement between the analytical and numerical methods. Hence, a parametric study is used to investigate in detail the stress variation under different opening dimensions, heterogeneous initial total stress conditions, and far-field pore pressure values. The proposed solution could be instrumental in the design of underground openings and deep mass alterations (that include local anthropogenic damage zones). It could also be used to provide reinforcement solutions where stresses can reach the mechanical stability thresholds.
Xiangjian Dong; Ali Karrech; Hakan Basarir; Mohamed Elchalakani; Chongchong Qi. Closed-Form Solution to the Poromechanics of Deep Arbitrary-Shaped Openings Subjected to Rock Mass Alteration. International Journal of Geomechanics 2020, 20, 04020223 .
AMA StyleXiangjian Dong, Ali Karrech, Hakan Basarir, Mohamed Elchalakani, Chongchong Qi. Closed-Form Solution to the Poromechanics of Deep Arbitrary-Shaped Openings Subjected to Rock Mass Alteration. International Journal of Geomechanics. 2020; 20 (12):04020223.
Chicago/Turabian StyleXiangjian Dong; Ali Karrech; Hakan Basarir; Mohamed Elchalakani; Chongchong Qi. 2020. "Closed-Form Solution to the Poromechanics of Deep Arbitrary-Shaped Openings Subjected to Rock Mass Alteration." International Journal of Geomechanics 20, no. 12: 04020223.
Lithium slag (LS), a waste residue produced during the processing of lithium products, has rarely been utilized in the cement industries. The disposal of LS as solid waste causes serious land occupation and environmental pollution. This research work was performed by mixing the LS with NaOH to improve its pozzolanic activity. The blended binder (defined as CPL) was prepared by replacing 30 wt% of Portland pozzolana cement (PPC) with LS-NaOH mixtures. Retardations for early strength development (3 and 7 d) were observed in the CPL specimens, according to the results on the unconfined compressive strength (UCS) test. The specimens richer in NaOH showed higher strength, and the 28 and 56 d strengths of CPL6.0 specimens increased to 32.3 and 39.7 MPa, respectively, which were similar to the strength of PPC specimens (33.4 and 41.8 MPa). It was indicated by thermo-gravimetric analysis (TGA) that the weight-loss rates of CPL6.0 specimens in the intervals 40–200 °C, 400–500 °C, and 600–800 °C were 10.73%, 1.66%, and 1.24%, respectively, which were higher and closer to the PPC specimens than those for CPL0, CPL2.0, and CPL4.0 specimens. Scanning electron microscopy (SEM) micrographs showed that more calcium silicate hydrate (CSH) and less calcium hydroxide (CH) were observed in the specimens richer in NaOH. It was indicated that the degree of pozzolanic reaction increased with the content of NaOH, also in good agreement with the results of UCS tests and TGA. Results on leaching experiments showed that the contents of harmful elements in CPL specimens were far below the standard values for category III of China's quality standard of groundwater (DZ/T 0290–2015). In addition, the feasibility of the engineering application of CPL as a supplementary binder was demonstrated by the industrial experiment. Results on the industrial experiment indicated that the CPL4.0- and CPL6.0-based binders both satisfied the strength requirements for backfill mining in the lead–zinc mine in Gansu Province, China. It may be confirmed that LS, activated effectively by adding NaOH, could be utilized as supplementary cementitious material in the engineering application of backfill mining. The results of the present research can provide an effective and environmental approach to recycling useless LS.
Yan He; Qinli Zhang; QiuSong Chen; Jiwei Bian; Chongchong Qi; Qian Kang; Yan Feng. Mechanical and environmental characteristics of cemented paste backfill containing lithium slag-blended binder. Construction and Building Materials 2020, 271, 121567 .
AMA StyleYan He, Qinli Zhang, QiuSong Chen, Jiwei Bian, Chongchong Qi, Qian Kang, Yan Feng. Mechanical and environmental characteristics of cemented paste backfill containing lithium slag-blended binder. Construction and Building Materials. 2020; 271 ():121567.
Chicago/Turabian StyleYan He; Qinli Zhang; QiuSong Chen; Jiwei Bian; Chongchong Qi; Qian Kang; Yan Feng. 2020. "Mechanical and environmental characteristics of cemented paste backfill containing lithium slag-blended binder." Construction and Building Materials 271, no. : 121567.
The rehabilitation of the post-mining landscape is one of the intractable bottlenecks faced by the mining industry. Though plant restoration has been regarded as an efficient way, its application is often restricted by the physicochemical properties of the soil, i.e., macronutrient deficiencies. In this work, a novel plant restoration method was proposed that employs maize straw and ultrasonically pre-treated coal fly ash (UCFA) for soil amelioration. Seed germination experiments were performed to investigate the effect of maize straw leachates (MSLs) on the growth of maize, alfalfa, and soybean. Then, the influence of MSLs and UCFA on the physiological attributes, chlorophyll, and trace element concentrations of maize was studied by plant growth experiments. Our results show that: (i) the MSLs concentration had a significant effect on the plant growth and the optimum concentration was 20%; (ii) considering the physiological attributes of maize plants, MSLs and UCFA benefited its growth in most cases. The UCFA proportion should be less than 20 v.% for optimum performance; (iii) the mixture of MSLs and UCFA could generally increase the chlorophyll and decrease trace element concentrations; and (iv) the optimum proportion was found to be soil:UCFA:MSLs = 70:20:10 and soil:UCFA:MSLs = 60:20:20, which achieved satisfactory performance during engineering applications.
Xiang Lu; Wei Zhou; Chongchong Qi; Meng Yang. Enhanced Plant Restoration in Open-Pit Mines Using Maize Straw and Ultrasonically Pre-Treated Coal Fly Ash. Sustainability 2020, 12, 9307 .
AMA StyleXiang Lu, Wei Zhou, Chongchong Qi, Meng Yang. Enhanced Plant Restoration in Open-Pit Mines Using Maize Straw and Ultrasonically Pre-Treated Coal Fly Ash. Sustainability. 2020; 12 (22):9307.
Chicago/Turabian StyleXiang Lu; Wei Zhou; Chongchong Qi; Meng Yang. 2020. "Enhanced Plant Restoration in Open-Pit Mines Using Maize Straw and Ultrasonically Pre-Treated Coal Fly Ash." Sustainability 12, no. 22: 9307.
The disposal of cement-based construction waste and the reduction in cement consumption are two bottlenecks for the cement and concrete industry. However, these two issues can be tackled simultaneously through reactivating hydrated cement paste (HCP) to be used as new cementitious materials. Moreover, the reactivated HCP can be used together with other solids waste, such as coal gangue (CG), to improve the grinding effect and reactivity. This study aims to investigate the co-utilization of HCP and CG with special focus on its flowability, mechanical properties, phase composition and hydration mechanism. It has been found that the addition of CG could increase the grinding time before agglomeration happened (from 6 min at 0% CG to 15 min at 15% CG and 35 min at 30% CG). Therefore, the final grain size of solid particles was decreased after CG addition. Partial replacement of ordinary Portland cement with HCP and CG could lead to a decrease in the flowability (between 2.3% and 7.1% depending on the HCP to CG proportion). The flowability was further decreased after the calcination. The strength of the mortar was also decreased after HCP + CG replacement (between 21.6% and 36.6%). However, the calcination activation promoted strength development. XRD and FT-IR results indicate the HCP calcination led to the generation of lime and β-C2S, the content of which had a positive correlation with the calcination temperature. The addition of CG resulted in a decrease of the lime content and the generation of new mineralogical phases, including quartz and mayenite.
Xuyang Shi; Qingxiang Cai; Chongchong Qi; Linglei Zhang; Xiang Lu; Wei Zhou; Binyu Zhao. Co-utilization of reactivated cement pastes with coal gangue. Construction and Building Materials 2020, 270, 121423 .
AMA StyleXuyang Shi, Qingxiang Cai, Chongchong Qi, Linglei Zhang, Xiang Lu, Wei Zhou, Binyu Zhao. Co-utilization of reactivated cement pastes with coal gangue. Construction and Building Materials. 2020; 270 ():121423.
Chicago/Turabian StyleXuyang Shi; Qingxiang Cai; Chongchong Qi; Linglei Zhang; Xiang Lu; Wei Zhou; Binyu Zhao. 2020. "Co-utilization of reactivated cement pastes with coal gangue." Construction and Building Materials 270, no. : 121423.
Understanding the creep behaviours of rocks is essential for the long-term stability of underground excavations in mining engineering. Creep behaviours are more important when the mining depth is greater, which leads to the emergence of weak rock masses and high in situ stresses. In this study, the creep behaviours of argillaceous sandstone (AS) were systematically investigated. For the experimental investigation, creep tests were conducted on AS with different confining pressures (3, 6, 9, 12, 15, and 18 MPa) using an MTS815.02 rock mechanics test system. The mechanical characteristics of AS were analysed. For the numerical study, a nonlinear creep model of AS under equal and different confining pressures was established based on rock creep theory and plastic theory. The results showed that confining pressure could effectively improve the creep failure strength of AS, accelerating its creep deformation rate and process and reducing the final expansion volume. The nonlinear creep model was embedded in the FLAC3D software, and the experimental and numerical results agreed well. The experimental investigation and proposed creep model can provide important guidance in underground mines for safe long-term stability of underground excavations.
Huaiguo Zheng; Qingxiang Cai; Wei Zhou; Xiang Lu; Ming Li; Chongchong Qi; Izhar Jiskani; Yu Zhang. Creep Behaviours of Argillaceous Sandstone: An Experimental and Modelling Study. Applied Sciences 2020, 10, 7602 .
AMA StyleHuaiguo Zheng, Qingxiang Cai, Wei Zhou, Xiang Lu, Ming Li, Chongchong Qi, Izhar Jiskani, Yu Zhang. Creep Behaviours of Argillaceous Sandstone: An Experimental and Modelling Study. Applied Sciences. 2020; 10 (21):7602.
Chicago/Turabian StyleHuaiguo Zheng; Qingxiang Cai; Wei Zhou; Xiang Lu; Ming Li; Chongchong Qi; Izhar Jiskani; Yu Zhang. 2020. "Creep Behaviours of Argillaceous Sandstone: An Experimental and Modelling Study." Applied Sciences 10, no. 21: 7602.
In view of high ground stress, high geothermal temperature, and thermal hazard during deep mineral resource exploitation, the concept of phase-change heat storage backfill was put forward in this study. Further, the corresponding technical system was constructed and the main content involved in technical system, which is the optimized proportion of the backfill slurry added with phase-change materials (PCMs), was examined. Moreover, we elaborated upon the collaborative optimization of a backfill body’s mechanical and thermal properties and the mutual cooperation on backfill mining, geothermal energy exploitation, and simultaneous stope cooling. The heat transfer behavior of a backfill body plays a key role in technology system. We numerically simulated the heat transfer among a backfill body, surrounding rock, and airflow in the heat storage process, as well as the heat transfer between backfill body and cold fluid during the heat release process. The temperature distribution of a backfill body at different heat storage/heat release times—i.e., the temperature distribution and its evolution—with heat transfer were revealed and analyzed. This study can provide theoretical guidance for a phase-change heat storage backfill, as it has an important significance for the collaborative exploitation of mineral resources and geothermal energy.
Xiaoyan Zhang; Muyan Xu; Li Liu; Lang Liu; Mei Wang; Haiwei Ji; Ki-Il Song. The Concept, Technical System and Heat Transfer Analysis on Phase-Change Heat Storage Backfill for Exploitation of Geothermal Energy. Energies 2020, 13, 4755 .
AMA StyleXiaoyan Zhang, Muyan Xu, Li Liu, Lang Liu, Mei Wang, Haiwei Ji, Ki-Il Song. The Concept, Technical System and Heat Transfer Analysis on Phase-Change Heat Storage Backfill for Exploitation of Geothermal Energy. Energies. 2020; 13 (18):4755.
Chicago/Turabian StyleXiaoyan Zhang; Muyan Xu; Li Liu; Lang Liu; Mei Wang; Haiwei Ji; Ki-Il Song. 2020. "The Concept, Technical System and Heat Transfer Analysis on Phase-Change Heat Storage Backfill for Exploitation of Geothermal Energy." Energies 13, no. 18: 4755.
Voids (referred to as “stopes”) are generally created during underground mining activities and can lead to both local and regional geotechnical instabilities. To assist in managing the stability of mining-related voids and improving the recovery of orebodies, tailing-based backfill technology has been widely used around the world. In the design of tailing-based backfill strategy, the specific function and engineering requirements of the filling are intimately dependent on the stress distribution within the backfilled stope. In this paper, the main mechanics involved in tailing-based backfill in underground mines, which include arching, consolidation, hydration process, and movement of surrounding rocks, are reviewed. Research on the safety of a barricade and stability of an exposed fill face are also presented. In conclusion, the back-filling process should be performed on the basis of a better understanding of the complicated interactions of the mechanisms of filling, consolidation, and hydration process (when cement is added).
Xu Zhao; Andy Fourie; Chong-Chong Qi. Mechanics and safety issues in tailing-based backfill: A review. International Journal of Minerals, Metallurgy, and Materials 2020, 27, 1165 -1178.
AMA StyleXu Zhao, Andy Fourie, Chong-Chong Qi. Mechanics and safety issues in tailing-based backfill: A review. International Journal of Minerals, Metallurgy, and Materials. 2020; 27 (9):1165-1178.
Chicago/Turabian StyleXu Zhao; Andy Fourie; Chong-Chong Qi. 2020. "Mechanics and safety issues in tailing-based backfill: A review." International Journal of Minerals, Metallurgy, and Materials 27, no. 9: 1165-1178.
Environment-friendly disposal of coal fly ash (CFA) is essential for sustainable development and cleaner production of electricity in thermal power plants. Although CFA has been employed for soil amelioration, direct application of CFA to soil may pose risks such as heavy metal contamination. This study investigated recycling of CFA through a novel method, which employs the ultrasonic treatment of CFA before its application. Physico-chemical properties of refuse dump soil and CFA were analysed. Subsequently, the effect of ultrasonic treatment on the physico-chemical properties of CFA was investigated. Different ultrasonic parameters (ultrasonic frequency, time interval, and temperature) were studied using response surface methodology. Finally, plant growth experiments were conducted to verify the feasibility of using ultrasonically treated CFA (UTCFA) for soil amelioration. The results show that untreated CFA cannot be used for soil amelioration due to its unsuitable high pH (10.20) and threatening concentrations of trace elements (6.80 mg/kg for Cadmium and 109.75 mg/kg for Arsenic). Ultrasonic treatment increases the soil amelioration properties of CFA by decreasing pH (to 8.50–9.20), decreasing concentrations of Cadmium and Arsenic (satisfying GB 15618-2018), and improving the water-holding capacity of CFA (reducing water loss). Plant indicators confirm the feasibility of using UTCFA for soil amelioration and suggest that the optimum UTCFA proportion is 20%. This study is a benchmark for the utilisation of ultrasonic treatment to improve the soil amelioration properties of CFA.
Wei Zhou; Xiang Lu; Chongchong Qi; Meng Yang. Utilisation of ultrasonic treatment to improve the soil amelioration property of coal fly ash. Journal of Environmental Management 2020, 276, 111311 .
AMA StyleWei Zhou, Xiang Lu, Chongchong Qi, Meng Yang. Utilisation of ultrasonic treatment to improve the soil amelioration property of coal fly ash. Journal of Environmental Management. 2020; 276 ():111311.
Chicago/Turabian StyleWei Zhou; Xiang Lu; Chongchong Qi; Meng Yang. 2020. "Utilisation of ultrasonic treatment to improve the soil amelioration property of coal fly ash." Journal of Environmental Management 276, no. : 111311.
Waste minimization is a major approach whereby many industries decrease environmental pollution and promote cleaner production. To achieve sustainable development, a novel idea is proposed herein to recycle magnesium slag (MS) and high-calcium fly ash (FA) into cementitious materials which are then mixed with aeolian sand (AS) to produce a type of paste backfill (MFPB) material that can be used in the mining industry. The rheological and mechanical properties of backfill materials with different FA contents were investigated. The results reveal that: (1) fresh MFPB mortars with different proportions conformed to the Herschel–Bulkley model. The yield stress initially decreased, and then increased with rising FA content. When the FA content was less than 20 wt%, the rheology of the MFPB surpassed that of the pure MS mortar, and an FA content of 10 wt%, yielded the best rheological properties of the fresh MFPB mortar. The mini-slump value, which was between 108 mm (MS-FA0) and 141 mm (MS-FA10), first increased and then decreased with increasing FA content. (2) The unconfined compressive strength (UCS) increased with extended curing times and FA contents, as well as the early-age strength development, which accelerated with increasing FA content. The UCS at 28 d escalated from 2.607 MPa (MS-FA0) to 7.491 MPa (MS-FA40). (3) The microstructure of the MFPB samples was discovered to agree with the UCS results. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were conducted to investigate the hydration products of the MFPB samples. The hydration mechanism of the MS and FA mixture was discussed, and the former was less reactive when used individually, although its reactivity increased with the addition of high-calcium FA. CaO dissolution in the MS and FA led to the generation of Ca(OH)2, which was a prerequisite for the successive pozzolanic reaction between the MS and FA. This study investigated the feasibility of the co-disposal of MS and FA, which could significantly promote a cleaner mineral production, and mining industry, when used together with backfill technology.
Lang Liu; Shishan Ruan; Chongchong Qi; Bo Zhang; Bingbing Tu; Qixing Yang; K.I.-I.L. Song. Co-disposal of magnesium slag and high-calcium fly ash as cementitious materials in backfill. Journal of Cleaner Production 2020, 279, 123684 .
AMA StyleLang Liu, Shishan Ruan, Chongchong Qi, Bo Zhang, Bingbing Tu, Qixing Yang, K.I.-I.L. Song. Co-disposal of magnesium slag and high-calcium fly ash as cementitious materials in backfill. Journal of Cleaner Production. 2020; 279 ():123684.
Chicago/Turabian StyleLang Liu; Shishan Ruan; Chongchong Qi; Bo Zhang; Bingbing Tu; Qixing Yang; K.I.-I.L. Song. 2020. "Co-disposal of magnesium slag and high-calcium fly ash as cementitious materials in backfill." Journal of Cleaner Production 279, no. : 123684.
C.C. Qi, Big data management in the mining industry, Int. J. Miner. Metall. Mater., 27(2020), No. 2, p. 131. Article Google Scholar C.Q. Cui, B. Wang, Y.X. Zhao, Y.J. Zhang, and L.M. Xue, Risk management for mine closure: A cloud model and a hybrid semiquantitative decision method, Int. J. Miner. Metall. Mater., 27(2020), No. 8, p. 1021. Google Scholar D. Liu, M.J. Lian, C.W. Lu, and W. Zhang, Effect of the lenticles on moisture migration in capillary zone of tailings dam, Int. J. Miner. Metall. Mater., 27(2020), No. 8, p. 1036. Google Scholar D. Wu, R.K. Zhao, C.W. Xie, and S. Liu, Effect of curing humidity on performance of cemented paste backfill, Int. J. Miner. Metall. Mater., 27(2020), No. 8, p. 1046. Google Scholar J. Kiventerä, P. Perumal, J. Yliniemi, and M. Illikainen, Mine tailings as a raw material in alkali-activation: A review, Int. J. Miner. Metall. Mater., 27(2020), No. 8, p. 1009. Google Scholar Download references School of Civil, Environmental and Mining Engineering, University of Western Australia, Crawley, WA, 6009, Australia Chong-chong Qi & Andy Fourie School of Resources and Safety Engineering, Central South University, Changsha, 410083, China Chong-chong Qi & Qiu-song Chen Newmont Corporation, Subiaco, WA, 6008, Australia Ryan Veenstra You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar Correspondence to Chong-chong Qi. Chong-chong Qi is currently a professor at School of Resources and Safety Engineering, Central South University, China. He received his Bachelor degree from China University of Mining and Technology, China, and PhD degree from The University of Western Australia, Australia. Prof. Qi has published over 60 peer reviewed SCI papers. He is an Editorial Board Member of SCI journals ‘International Journal of Minerals, Metallurgy, and Materials’ and ‘Advances in Civil Engineering’. Moreover, he has served as chair and committee member for many international conferences. The research interests of Prof. Qi include cemented paste backfill, environmental assessment and protection, mine closures, construction stability, etc. Andy Fourie is a Professor in the Faculty of Engineering and Mathematical Sciences at University of Western Australia, Australia. He has Bachelor and Master degrees from the University of the Witwatersrand in South Africa and a PhD from Imperial College, University of London, UK. After a period in consulting practice with SRK in Johannesburg, he began an academic career at the University of Queensland, Australia. His research is inmitigating the impact of mining and municipal solid waste disposal. Andy has published over 200 articles, including more than 80 in international journals. He has recently been appointed to the ICMM (International Council on Mining and Metals) ‘expert review panel’ for the ICMM Global review of tailings storage facility standards and critical controls. He has contributed to a new series of guidelines for managing mine tailings in Australia, as well as developing a document for the International Atomic Energy Association on barrier systems for retainin guranium mining waste. Qiu-song Chen is an associate professor at School of Resources and Safety Engineering, Central South University, China. He has published more than 50 papers, among them around 30 are published in reputed SCI journals. Assoc. Prof. Chen has helped SCI journals review more than 60 papers and served as lead guest editor and guest editor for several special issues. The total citation was more than 800 (Google Scholar) and several papers have been selected as ESI highly-cited papers. Ryan Veenstra received his bachelor’s degree in Applied Science (Geological Engineering) from University of Waterloo, Canada. He earned his Ph.D. from University of Toronto, Canada. Dr. Veenstra has worked over 10 years for the mining industry in Australia and Canada. Dr. Veenstra is currently working as Senior backfill Engineer at Newmont Mining Corporation, Northern Territory, Australia. Reprints and Permissions Qi, C., Fourie, A., Chen, Q. et al. Editorial for special issue on mitigating the impacts of mining. Int J Miner Metall Mater 27, 1007–1008 (2020). https://doi.org/10.1007/s12613-020-2152-7 Download citation Published: 15 August 2020 Issue Date: August 2020 DOI: https://doi.org/10.1007/s12613-020-2152-7
Chong-Chong Qi; Andy Fourie; Qiu-Song Chen; Ryan Veenstra. Editorial for special issue on mitigating the impacts of mining. International Journal of Minerals, Metallurgy and Materials 2020, 27, 1007 -1008.
AMA StyleChong-Chong Qi, Andy Fourie, Qiu-Song Chen, Ryan Veenstra. Editorial for special issue on mitigating the impacts of mining. International Journal of Minerals, Metallurgy and Materials. 2020; 27 (8):1007-1008.
Chicago/Turabian StyleChong-Chong Qi; Andy Fourie; Qiu-Song Chen; Ryan Veenstra. 2020. "Editorial for special issue on mitigating the impacts of mining." International Journal of Minerals, Metallurgy and Materials 27, no. 8: 1007-1008.
In underground mining, there has been an increasing use of “cemented paste” for the backfilling of stopes. As this cemented paste backfill (CPB) enters the stope as a fluid, shotcrete barricades are often used to retain the fill material during and after the filling operations. However, failures of barricades have been reported around the world in recent years. This paper presents an analytical solution based on the elastic thin plate theory for calibrating the design of shotcrete barricades in underground mines using CPB. This solution was used to determine the quantitative relationships between the lateral loading from the paste and the barricade response during the backfilling process. The results show that the proposed solution agrees well with in situ data. According to the actual barricade responses, the acceptable tensile stress and an analysis method of cracks development are proposed. The proposed solution has practical significance for underground mines.
Xu Zhao; Andy Fourie; Ryan Veenstra; Chong-Chong Qi. Safety of barricades in cemented paste-backfilled stopes. International Journal of Minerals, Metallurgy, and Materials 2020, 27, 1054 -1064.
AMA StyleXu Zhao, Andy Fourie, Ryan Veenstra, Chong-Chong Qi. Safety of barricades in cemented paste-backfilled stopes. International Journal of Minerals, Metallurgy, and Materials. 2020; 27 (8):1054-1064.
Chicago/Turabian StyleXu Zhao; Andy Fourie; Ryan Veenstra; Chong-Chong Qi. 2020. "Safety of barricades in cemented paste-backfilled stopes." International Journal of Minerals, Metallurgy, and Materials 27, no. 8: 1054-1064.