scholarly journals Experimental Study and Application of Inorganic Solidified Foam Filling Material for Coal Mines

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Hu Wen ◽  
Duo Zhang ◽  
Zhijin Yu ◽  
Xuezhao Zheng ◽  
Shixing Fan ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Spontaneous Combustion ◽  
Setting Time ◽  
Coal Mines ◽  
Solidification Time ◽  
Filling Material ◽  
Air Leakage ◽  
Heat Accumulation ◽  
Effective Measure ◽  
Foam Filled

Spontaneous combustion of residual coal in a gob due to air leakage poses a major risk to mining safety. Building an airtight wall is an effective measure for controlling air leakage. A new type of inorganic solidified foam-filled material was developed and its physical and chemical properties were analyzed experimentally. The compressive strength of this material increased with the amount of sulphoaluminate cement. With an increasing water–cement ratio, the initial setting time was gradually extended while the final setting time firstly shortened and then extended. The change in compressive strength had the opposite tendency. Additionally, as the foam expansion ratio increased, the solidification time tended to decrease but the compressive strength remained approximately constant. With an increase in foam production, the solidification time increased and the compressive strength decreased exponentially. The results can be used to determine the optimal material ratios of inorganic solidified foam-filled material for coal mines, and filling technology for an airtight wall was designed. A field application of the new material demonstrated that it seals crossheadings tightly, leaves no fissures, suppresses air leakage to the gob, and narrows the width of the spontaneous combustion and heat accumulation zone.

scholarly journals Experimental Study and Application of LASC Foamed Concrete to Create Airtight Walls in Coal Mines

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Duo Zhang ◽  
Weifeng Wang ◽  
Jun Deng ◽  
Hu Wen ◽  
Xiaowei Zhai
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Coal Mines ◽  
Volume Ratio ◽  
Filling Material ◽  
Air Leakage ◽  
Initial Setting Time ◽  
Filling Materials ◽  
Foamed Concrete ◽  
Better Than

If an airtight wall in a coal mine leaks air, it may cause spontaneous combustion of residual coal in the gob and even cause a full-blown fire or gas explosion. In this study, we developed a new type of foamed concrete, low-alkalinity sulphoaluminate cement (LASC), to control air leakage. The performance of filling materials that were prepared by adding various dosages of foam to LASC was studied. The longer the curing period for the foam filling material of LASC, the better the crystallinity of the hydrated product. With an increasing foam dosage, the initial setting time gradually extends while the fluidity of the foam slurry decreases. The bubble rate of the filling material increases and the density decreases with increasing foam dosage. The compressive strength of the LASC filling material decreases with increasing foam dosage and increases with increasing curing time. In the LASC filling materials, the optimal volume ratio of foam dosage to gel slurry is 2. The crystallinity, initial gel time, and compressive strength of the LASC foaming materials are better than those of ordinary Portland cement (OPC) foaming materials. When the crossheading is filled with LASC foam cement, the deformation of the surrounding rock is less than 19 cm, and the air leakage prevention is better than that achieved with loess and fly-ash-cement foam. Thus, the proposed LASC foam material can be applied to the filling of the crossheading to efficiently prevent leakage in underground coal mines.

Biodentine: um substituto ao MTA?

2019 ◽  
Vol 9 (3) ◽  
pp. 29-36
Author(s):  
Maíra do Prado ◽  
Carolina Oliveira de Lima ◽  
Hugo Gonçalves Dutra ◽  
Jefferson Marion ◽  
Maria Das Graças Afonso Miranda Chaves ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Physicochemical Properties ◽  
Calcium Silicate ◽  
Setting Time ◽  
Filling Material ◽  
Retrograde Filling

Objetivo: o objetivo desse estudo é realizar uma revisão de literatura em relação às propriedades físico- -químicas e biológicas do Biodentine, seu emprego na Endodontia e discutir, com base nas evidências científicas encontradas na literatura, se esse material poderá ser um substituto ao MTA. Métodos: foi realizada uma busca na literatura na base de dados PubMed, usando os termos em inglês: Biodentine, calcium silicate, MTA, properties, setting time, radiopacity, solubility, physicochemical properties, porosity, hydration, biocompatibility, bioactivity, microhardness, compressive strength, bond strength, irrigants, furcal perforation, retrograde filling material, revitalization, revascularization, endodontics, apexification. Cinquenta artigos foram incluídos. Resultados: os artigos revisados sugerem que o Biodentine tem características favoráveis e que tem alcançado resultados promissores em relação ao MTA. Conclusão: o Biodentine pode ser considerado um eventual substituto ao MTA.

Mechanical Property Evaluation of IRM®/Chitosan Fiber Composite Temporary Filling Material

2010 ◽  
Vol 123-125 ◽  
pp. 487-490 ◽  
Author(s):  
Jia Horng Lin ◽  
Po Ching Lu ◽  
Chao Tsang Lu ◽  
Tzu Hsuan Chao ◽  
Ching Wen Lou
Keyword(s):  
Compressive Strength ◽  
Fiber Composite ◽  
Setting Time ◽  
Filling Material ◽  
Short Term ◽  
Leakage Test ◽  
Property Evaluation ◽  
Bacterial Leakage ◽  
Chitosan Fiber ◽  
Temporary Filling

The temporary filling material seals up the tooth cavity so as to prevent bacterial leakage and the second infection in the root-end treatment. Chitosan is biodegradable, bio-resorbable, non-toxic, and antibiotic. In this study, chitosan fiber is used to enhance the temporary filling material compressive strength and the tooth bite force. IRM® is reinforced by the 2, 4 and 6 wt% chitosan fibers, respectively. And after solidified the IRM®/ Chitosan fiber composite temporary filling material was obtained. Then setting time, solution test, compressive strength and dye micro-leakage of IRM®/ Chitosan fiber composite temporary filling material were be evaluated. In result, maximum compressive strength of IRM®/ Chitosan fiber composite temporary filling material was obviously increased 200 N than IRM® matrix. As to the micro-leakage test, no trace of leakage was found on the 7th day. Consequently, IRM®/ Chitosan fiber composite temporary filling material can be a good candidate in the short-term dental clinical surgery.

scholarly journals Numerical Simulation on goaf with different vertical distances in high-drainage roadways

2020 ◽  
Vol 194 ◽  
pp. 01017
Author(s):  
Rili Yang ◽  
Jianbin Cui ◽  
Fengfeng Yang ◽  
Jufeng Zhang ◽  
Lan Yu
Keyword(s):  
Spontaneous Combustion ◽  
Mine Safety ◽  
Fire Prevention ◽  
Air Leakage ◽  
Heat Accumulation ◽  
Distribution Law ◽  
Mine Fire ◽  
Leakage Field ◽  
Safety Production ◽  
Drainage Effect

High drainage roadway horizon parameters not only influence goaf drainage effect, but also have effect on the air leakage field and spontaneous combustion three zones’ distribution in the goaf. Combined with mine fire-prevention and goaf spontaneous combustion three zones recognition, it was put forward to stimulate the distribution law of goaf air leakage field and spontaneous combustion three zones with fluid mechanics software FLUENT. The results showed that the width of goaf oxidization and heat accumulation zone increased with high drainage roadway vertically. Through stimulation study, it supplies a certain method to reasonablely optimizatate high drainage roadway vertical parameters, which to a great extent ensures mine safety production, fire and gas prevention.

scholarly journals CHARACTERISTIC OF GLASS IONOMER CEMENT MATERIAL FOR CLINICAL DENTISTRY

2021 ◽  
Vol 1 (39) ◽  
pp. 83-90
Author(s):  
Hoa Thi Hong Huynh ◽  
Minh Ngoc Huynh ◽  
Minh Quang Do
Keyword(s):  
Compressive Strength ◽  
Tartaric Acid ◽  
Maleic Acid ◽  
Glass Powder ◽  
Setting Time ◽  
Glass Ionomer Cement ◽  
Filling Material ◽  
Glass Ionomer ◽  
Ion Release ◽  
Ionomer Cement

Glass ionomer cement (GIC), a thermoplastic polymer, is toughed by ionic bonding is used in dentistry as a filling material. The glass-powder used has some disadvantages such as: poor strength and toughness, and instability in water. Therefore, the aim of this work is to enhance mechanical and fluoride release properties of the GICs by modifying ingredients. The results show that the compressive strength reached to from 60.5 to 86.2 MPa, the setting time met the ISO 9917-1:2007 quality standard. This also suggests that, in addition to 35% PAA in water with Mw of 100,000, 5% of Maleic acid and 5% Tartaric acid to produce GIC which can be used as suitable materials for improving its fluoride ion release over 28 days. The average diameter (dmean) of glass powder for GICs was 14.3 mm; S.P. Surface area was 10,358 cm2=cm3, improvement of liquid composition includes 35% PAA in water with Mw of 100,000, 5% of Maleic acid and 5% Tartaric acid. The compressive strength after curing 28-day reaches from 60.5 to 86.2 MPa and the setting time responds with ISO 9917-1:2007. In conclusion, it was found that the GIC can release fluoride ions (F-) for the during of the examination period.

scholarly journals Properties and Engineering Applications of a New Goaf Grouting Filling Material

Geofluids ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-14
Author(s):  
Xiao Feng ◽  
Chong Xia ◽  
Sifeng Zhang ◽  
Chuangui Li ◽  
Hongkui Zhao ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Silicate ◽  
Traffic Engineering ◽  
Setting Time ◽  
Microstructural Analysis ◽  
Volume Ratio ◽  
Skeletal Structure ◽  
Filling Material ◽  
Technical Problems

In the treatment of goafs in traffic engineering, technical problems such as those related to large-volume grouting and the precise control of material properties are often encountered. To address these issues, we developed a new composite material comprising cement-fly ash-modified sodium silicate (C-FA-MS). The setting time, fluidity, unconfined compressive strength, and microstructure were varied for different proportions of cement-sodium silicate (C-S) slurry, cement-fly ash-sodium silicate (C-FA-S) slurry, and C-FA-MS slurry, and their performances were compared and analysed. The experimental results showed that the initial setting time of the slurry was the shortest when both the original sodium silicate volume ratio ( V S ) and modified sodium silicate volume ratio ( V MS ) were 0.2. The final setting time of the C-S and C-FA-S slurries tended to decrease but then increased with decrease in V S , while that of the C-FA-MS slurry increased with lower V MS . The fluidity of the C-FA-S and C-FA-MS slurries decreased with decrease in V S or V MS at different fly ash admixture ratios. The consolidation compressive strength of C-S increased with decreasing V S , while that of C-FA-S showed a considerable increase only when V S decreased from 0.4 to 0.2. Meanwhile, the compressive strength of the C-FA-MS concretions first increased and then decreased with decrease in V MS . Microstructural analysis revealed that there were more cracks in the C-S agglomerate, the fly ash in the C-FA-S agglomerate reduced the relative density of the skeletal structure, and the stronger cross-linking in the C-FA-MS agglomerate improved the strength of the agglomerate. Under the condition of unit grouting volume, the cost of the C-FA-MS slurry was approximately 44.7% and 31.3% lower than that of the C-S and C-FA-S slurries, respectively. The new C-FA-MS material was applied for the treatment of the goaf in the Wu Sizhuang coal mine. Core drilling detection and audiofrequency magnetotelluric survey revealed that the goaf was sufficiently filled.

Research & Development of Inorganic Solidified Foam Filling Material for Use in Coal Mines

2013 ◽  
Vol 803 ◽  
pp. 209-212 ◽  
Author(s):  
Xing Bing Yang
Keyword(s):  
Compressive Strength ◽  
Chemical Modification ◽  
Coal Mines ◽  
Dry Density ◽  
Filling Material ◽  
Research Development ◽  
Test Results ◽  
Foaming Agent ◽  
Orthogonal Experiments ◽  
Foam Filling

This research conducted chemical modification of foaming agent KH first, then determined the ratio of ingredients KH: SK: BH: SF: water of the foaming composite as 10:2:1:2:20 through orthogonal experiments, and made tests for relevant properties of samples at the said ingredient ratio and with dry density of 800 kg/m3, 900 kg/m3 and 1000 kg/m3 respectively determined by optimum seeking method via experiments. The test results show that the initial compressive strength of the material and its compressive strength after curing for 28 days are both relatively high.

Effects of Sodium Hydroxide Treatment Duration on the Physical Properties of IRM®/Polylactic Acid Composite Filling Materials

2013 ◽  
Vol 365-366 ◽  
pp. 999-1002
Author(s):  
Ching Wen Lou ◽  
Tzu Hsuan Chao ◽  
Chao Tsang Lu ◽  
Po Ching Lu ◽  
Jia Horng Lin
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Sodium Hydroxide ◽  
Polylactic Acid ◽  
Treatment Duration ◽  
Setting Time ◽  
Filling Material ◽  
Filling Materials ◽  
Naoh Solution ◽  
Sodium Hydroxide Treatment

The purpose of this study is to explore the influence of the sodium hydroxide (NaOH) treatment duration on the physical properties of the composite filling material. This study uses Intermediate Restorative Material (IRM®) as matrix and 2 % of polylactic acid (PLA) fiber as reinforcing material to make the IRM®/PLA composite filling material. Before being infused into the IRM® matrix, the 2-mm long PLA fiber is treated by NaOH solution for 5, 10, 15, 20, 30, 60, or 90 minutes. The setting time and compressive strength of resulting composite filling materials are evaluated, determining the optimum treatment duration is 60 minutes. The compressive strength is increased by 41 %.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

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