scholarly journals Effect of Calcined Hard Kaolin Dosage on the Strength Development of CPB of Fine Tailings with Sulphide

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Juanrong Zheng ◽  
Lijie Guo ◽  
Zhenbo Zhao
Keyword(s):  
Portland Cement ◽  
Pore Diameter ◽  
Strength Development ◽  
Cemented Paste Backfill ◽  
Curing Time ◽  
Curing Period ◽  
Fine Tailings ◽  
Paste Backfill ◽  
Strength And Durability

This study presents the effect of calcined hard kaolin (CHK) as replacement (15–50 wt.%) to Portland cement (PC) on the strength development of cemented paste backfill (CPB) of fine tailings containing sulphide. PC is used as binder at 20 wt.% dosage. The results show that CPB sample containing 30 wt.% CHK replacements produces the desired strength and durability (i.e., 26.1% increase in strength over the curing period between 28 d and 360 d). CPB without CHK does not produce the desired strength and durability (i.e., 32.8% losses in strength over the curing period between 90 d and 360 d). The quantity of expansive gypsum of CPB containing 30 wt.% CHK is obviously less than that of CPB without CHK. The porosity of the fine pore for pore diameter < 0.3 μm is obviously higher in CPB containing 30 wt.% CHK than in CPB without CHK, regardless of curing time. It can be concluded that CHK can be suitably exploited for CPB of fine tailings with sulphide to improve the strength and stability in short and long terms.

scholarly journals Strength Development Monitoring of Cemented Paste Backfill Using Guided Waves

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8499
Author(s):  
Wen He ◽  
Changsong Zheng ◽  
Shenhai Li ◽  
Wenfang Shi ◽  
Kui Zhao
Keyword(s):  
Uniaxial Compression ◽  
Wave Velocity ◽  
Guided Waves ◽  
Guided Wave ◽  
Strength Development ◽  
Cemented Paste Backfill ◽  
Curing Time ◽  
Acoustic Parameters ◽  
Paste Backfill ◽  
Wave Technique

The strength of cemented paste backfill (CPB) directly affects mining safety and progress. At present, in-situ backfill strength is obtained by conducting uniaxial compression tests on backfill core samples. At the same time, it is time-consuming, and the integrity of samples cannot be guaranteed. Therefore guided wave technique as a nondestructive inspection method is proposed for the strength development monitoring of cemented paste backfill. In this paper, the acoustic parameters of guided wave propagation in the different cement-tailings ratios (1:4, 1:8) and different curing times (within 42 d) of CPBs were measured. Combined with the uniaxial compression strength of CPB, relationships between CPB strength and the guided wave acoustic parameters were established. Results indicate that with the increase of backfill curing time, the guided wave velocity decreases sharply at first; on the contrary, attenuation of guided waves increases dramatically. Finally, both velocity and attenuation tend to be stable. When the CPB strength increases with curing time, guided wave velocity shows an exponentially decreasing trend, while the guided wave attenuation shows an exponentially increasing trend with the increase of the CPB strength. Based on the relationship curves between CPB strength and guided wave velocity and attenuation, the guided wave technique in monitoring the strength development of CPB proves feasible.

scholarly journals Strength Development and Strain Localization Behavior of Cemented Paste Backfills Using Portland Cement and Fly Ash

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3282 ◽  
Author(s):  
Zhao ◽  
Taheri ◽  
Soltani ◽  
Karakus ◽  
Deng
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Strain Localization ◽  
Image Correlation ◽  
Lateral Strain ◽  
Strength Development ◽  
Curing Time ◽  
Failure Patterns ◽  
Curing Period ◽  
Dic Technique

This study examines the combined performance of Portland cement (PC), the binder, and fly ash (FA), the additive, towards improving the mechanical performance of the South Australian copper-gold underground mine cemented paste backfill (CPB) system. A series of unconfined compressive strength (UCS) tests were carried out on various mix designs to evaluate the effects of binder and/or additive contents, as well as curing time, on the CPB’s strength, stiffness and toughness. Moreover, the failure patterns of the tested samples were investigated by means of the three-dimensional digital image correlation (DIC) technique. Making use of several virtual extensometers, the state of axial and lateral strain localization was also investigated in the pre- and post-peak regimes. The greater the PC content and/or the longer the curing period, the higher the developed strength, stiffness and toughness. The use of FA alongside PC led to further strength and stiffness improvements by way of inducing secondary pozzolanic reactions. Common strength criteria for CPBs were considered to assess the applicability of the tested mix designs; with regards to stope stability, 4% PC + 3% FA was found to satisfy the minimum 700 kPa threshold, and thus was deemed as the optimum choice. As opposed to external measurement devices, the DIC technique was found to provide strain measurements free from bedding errors. The developed field of axial and lateral strains indicated that strain localization initiates in the pre-peak regime at around 80% of the UCS. The greater the PC (or PC + FA) content, and more importantly the longer the curing period, the closer the axial stress level required to initiate localization to the UCS, thus emulating the failure mechanism of quasi-brittle materials such as rock and concrete. Finally, with an increase in curing time, the difference between strain values at the localized and non-localized zones became less significant in the pre-peak regime and more pronounced in the post-peak regime.

scholarly journals Effects of Superplasticizer on the Hydration, Consistency, and Strength Development of Cemented Paste Backfill

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 381 ◽  
Author(s):  
Jian Zhang ◽  
Hongwei Deng ◽  
Abbas Taheri ◽  
Junren Deng ◽  
Bo Ke
Keyword(s):  
Underground Mines ◽  
Strength Development ◽  
Strength Increase ◽  
Strengthening Effect ◽  
Cemented Paste Backfill ◽  
Solid Concentration ◽  
Resonance System ◽  
Low Field ◽  
Binder Ratio ◽  
Paste Backfill

The strength and consistency of cemented paste backfill (CPB) are of key concerns in the stope stability and cost control for underground mines. It is common practice to use additives, such as superplasticizer, to improve the performance of CPB. This study mainly focuses on the effects of superplasticizer on the hydration, consistency, and strength of CPB. In this study, a polynaphtalene sulfonate was used as the superplasticizer. The binder is a mix of 33.3% ordinary Portland cement and 66.7% fly ash. The CPB specimens with a tailings-binder ratio of 3:1 and a solid concentration of 70% were then tested by a low field nuclear magnetic resonance system after different hydration times. Effects of polynaphtalene sulfonate on the hydration, fluidity, and strength were investigated. Results showed that the polynaphtalene sulfonate has a strong influence on short-duration hydration, which may contribute to the strength increase of CPB. It has been demonstrated that the polynaphtalene sulfonate improved the fluidity of the CPB mixture. With the increased dosage of polynaphtalene sulfonate, the slump increased. It was also found that the polynaphtalene sulfonate dosage has a negligible effect on the 1 day (d) strength while it has a strengthening effect on the 7 d, 14 d, and 28 d strength of CPB specimens.

Effects of curing time and ice-to-water ratio on performance of cemented paste backfill containing ice slag

2019 ◽  
Vol 228 ◽  
pp. 116639 ◽  
Author(s):  
Lang Liu ◽  
Chao Zhu ◽  
Chongchong Qi ◽  
Mei Wang ◽  
Chao Huan ◽  
...  
Keyword(s):  
Cemented Paste Backfill ◽  
Curing Time ◽  
Paste Backfill ◽  
Water Ratio

Fluidity and Mechanical Behavior of Cement Solidified Lead-Zinc Mine Tailings

2014 ◽  
Vol 898 ◽  
pp. 383-386 ◽  
Author(s):  
Chun Lei Zhang ◽  
Shun Cai Wang ◽  
Fan Lu Min
Keyword(s):  
Mine Tailings ◽  
Cement Content ◽  
Strength Increase ◽  
Cemented Paste Backfill ◽  
Curing Time ◽  
Test Results ◽  
The World ◽  
Paste Backfill ◽  
Lead Zinc ◽  
Zinc Mine

Cemented paste backfill method has been widely used in many modern mines throughout the world due to the increasingly stringent environmental regulations and short of disposal land. This study presents experimental results on the use of Portland cement in the solidification of Pb-Zn tailings in China. Test results show UCS strength increase lineally with cement content, tailings concentration, and curing time, respectively. There exist a minimum cement content and tailings concentration to produce obvious strength. The fluidity decrease quickly with cement proportion and tailings concentration, under the satisfying of a minimum pumping fluidity, the increase of tailings concentration can effectively reduce the cement consumption so as to decrease the treatment cost.

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