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

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.

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

Advances in Materials Science and Engineering ◽

10.1155/2017/3419801 ◽

2017 ◽

Vol 2017 ◽

pp. 1-13 ◽

Cited By ~ 3

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.

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Properties and Engineering Applications of a New Goaf Grouting Filling Material

Geofluids ◽

10.1155/2022/6778076 ◽

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.

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.365-366.999 ◽

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 %.

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

Materials ◽

10.3390/ma14071611 ◽

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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Aplikasi Response Surface Methodology pada Optimasi Penambahan Blast Furnace Slag Terhadap Waktu Pengikatan dan Kuat Tekan Semen

Jurnal Teknik Kimia dan Lingkungan ◽

10.33795/jtkl.v4i1.150 ◽

2020 ◽

Vol 4 (1) ◽

pp. 61

Author(s):

Hardjono Hardjono ◽

Cucuk Evi Lusiani ◽

Agung Ari Wibowo ◽

Mochammad Agung Indra Iswara

Keyword(s):

Compressive Strength ◽

Response Surface Methodology ◽

Blast Furnace ◽

Response Surface ◽

Blast Furnace Slag ◽

Setting Time ◽

Initial Setting Time ◽

Initial Setting ◽

Central Composite ◽

Furnace Slag

Produksi semen setengah jadi (clinker) membutuhkan energi yang tinggi sehingga menggunakan batu bara dalam jumlah besar. Hal ini menyebabkan biaya produksi dari pabrik semen juga tinggi. Kebutuhan energi yang besar untuk menghasilkan clinker tersebut dapat dikurangi dengan menambahan blast furnace slag sebagai campuran pembuatan semen. Campuran clinker dapat menghasilkan produk semen yang memiliki waktu pengikatan dan kuat tekan sesuai SNI. Pengaruh penambahan blast furnace slag sebagai campuran clinker terhadap waktu pengikatan dan kuat tekan semen dapat dioptimalkan dengan response surface methodology (RSM) menggunakan Central Composite Design (CCD). Optimasi dengan menggunakan RSM bertujuan untuk mengetahui kondisi optimum pada penambahan blast furnace slag dan clinker terhadap variabel respon berupa waktu pengikatan awal, waktu pengikatan akhir, dan kuat tekan. Hasil uji ANOVA dan analisis response surface menunjukkan bahwa penambahan blast furnace slag sebagai campuran dalam pembuatan semen memberikan pengaruh yang signifikan terhadap waktu pengikatan awal, waktu pengikatan akhir, dan kuat tekan. Penambahan 5% blast furnace slag dengan 92,5% clinker pada campuran clinker dan gypsum merupakan kondisi optimum yang memberikan pengaruh signifikan terhadap variabel respon.The production of clinker consumes high energy and causes high production cost of cement industry. It can be reduced by adding blast furnace slag as a mixture in cement production. The blast furnace slag - clinker mixture can produce cement with setting time and compressive strength according to SNI. The effect of the addition of blast furnace slag as a clinker mixture to the setting time and compressive strength of cement can be optimized by response surface methodology (RSM) using Central Composite Design (CCD). Optimization by using RSM aims to determine the optimum condition of the blast furnace slag – clinker mixture to the initial setting time, final setting time, and compressive strength. ANOVA test results and response surface analysis show that the addition of blast furnace slag into the cement mixture has a significant influence on the initial setting time, final setting time, and compressive strength. The addition of 5% blast furnace slag with 92.5% clinker in the mixture of clinker and gypsum is the optimum condition which gives a significant effect on the response variable.

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Analysis of the Influence of Crystalline Admixtures at Early Age Performance of Cement-Based Mortar by Electrical Resistance Monitoring

Materials ◽

10.3390/ma14195705 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5705

Author(s):

Rubén Beltrán Cobos ◽

Fabiano Tavares Pinto ◽

Mercedes Sánchez Moreno

Keyword(s):

Compressive Strength ◽

Thermogravimetric Analysis ◽

Remote Monitoring ◽

Electrical Resistance ◽

Setting Time ◽

Early Age ◽

Resistance Monitoring ◽

Initial Setting Time ◽

Characterization Techniques ◽

Initial Setting

Crystalline admixtures are employed for waterproofing concrete. This type of admixtures can affect the early age performance of cement-based mixes. The electrical resistance properties of cement have been related to the initial setting time and to the hydration development. This paper proposes a system for remote monitoring of the initial setting time and the first days of the hardening of cement-based mortars to evaluate the effect of the incorporation of crystalline admixtures. The electrical resistance results have been confirmed by other characterization techniques such as thermogravimetric analysis and compressive strength measurements. From the electrical resistance monitoring it has been observed that the incorporation of crystalline admixtures causes a delay in the initial setting time and hydration processes. The measurements also allow to evaluate the influence of the amount of admixture used; thus, being very useful as a tool to define the optimum admixture dosage to be used.

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Mechanical Property Evaluation of Fiber-Reinforced and Fabric-Reinforced Zinc Oxide-Eugenol Temporary Filling Materials

Journal of Engineered Fibers and Fabrics ◽

10.1177/155892501400900220 ◽

2014 ◽

Vol 9 (2) ◽

pp. 155892501400900

Author(s):

Chao-Tsang Lu ◽

Jia-Horng Lin

Keyword(s):

Zinc Oxide ◽

Composite Materials ◽

Dental Treatment ◽

Statistical Significance ◽

Setting Time ◽

Compressive Load ◽

Filling Material ◽

Fiber Reinforced ◽

Filling Materials ◽

Zinc Oxide Eugenol

Zinc oxide-eugenol (ZOE) is usually applied clinically as dental filling material for thermal insulation and temporary restoration. The objective of this study was to use ZOE as a composite matrix and low melting-point polyester fibers or fabrics as reinforcement. The added fibers or fabrics increased the composite materials’ compressive load by 250 N and 290 N, respectively. Fiber length and thermal-drying temperatures had no significant influence on setting time ( p>0.05), but the degree of solubility of the filling material had statistical significance ( p<0.05). Only the compressive load results were raised at the end of the curve. The optimum compressive load results, 290 N and 331 N, were observed in the 10 mm PET fiber processed at 130 °C. With its excellent compressive load, this composite material has the ability to sustain a bigger bite force; thus, the fiber-reinforced or fabric-reinforced composite materials are feasible for temporary clinical dental treatment.

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Effective binder based on the artificial anhydrite for manufacturing of filling mixtures

MATEC Web of Conferences ◽

10.1051/matecconf/201819303048 ◽

2018 ◽

Vol 193 ◽

pp. 03048

Author(s):

Nadezda Galtseva ◽

Anfisa Bogdanova

Keyword(s):

Compressive Strength ◽

Setting Time ◽

Potassium Sulfate ◽

Technological Properties ◽

Start Time ◽

Filling Materials ◽

Binder Ratio ◽

Sufficient Set ◽

Concentrated Sulfuric Acid ◽

Derivation Method

The article exposes the results of research on the development of filling mixtures based on artificial anhydrite obtained after the interaction of concentrated sulfuric acid and limestone flour. The anhydrite derivation method has a significant impact on its properties and brings more options for the application. The key features of artificial anhydrite are high compressive strength which is more than 50 MPa and extended setting time which is more than 10 hours. In order to use it as a binder in the filling mixtures, it is necessary to modify properties of the anhydrite by integrating the hardening activators. In the relation to the study it was found that the optimal activator providing desirable setting start time (at least 2 hours) and a sufficient set of strength in the first 7 days of hardening is a mixture of 5% portland cement CEM I 42,5 and 1% of potassium sulfate, where 100% is the mass of binder. The additional inclusion of Melment F10 plasticizer in the amount of 0.4 to 1% of the binder ensures the achievement of the such parameters as the 0.3 water-binder ratio, setting start from 120 to 225 min, final setting time from 180 to 355 min, compressive strength after 24 hours from 6.9 to 13.3 MPa, after 7 days from 24.0 to 33.5 MPa. The microstructure of the binder has been analyzed and the modification options of the artificial anhydrite have been revealed in order to regulate its technical and technological properties., Two compounds of the filling mixture have been developed on the basis of the obtained binder, technical properties of compounds satisfy the maximum requirements for filling materials for depleted underground spaces. Research results have shown an opportunity and a prospectively of integrating the modified artificial anhydrite in structures of filling mixtures.

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Preparation of Portland Cement with Gold Ore Tailings

Advances in Materials Science and Engineering ◽

10.1155/2019/1324065 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Qiang Wang ◽

Geng Yao ◽

Xiangnan Zhu ◽

Junxiang Wang ◽

Peng Wu ◽

...

Keyword(s):

Compressive Strength ◽

Flexural Strength ◽

Portland Cement ◽

Raw Materials ◽

Setting Time ◽

Hydration Product ◽

Difficult Problem ◽

Initial Setting Time ◽

Gold Ore ◽

Curing Age

The disposal of gold ore tailings (GTs) has been a very difficult problem for a long time. Thus, this study explored a new approach to the management of GTs by preparing Portland cement. Physical properties, reaction mechanisms, and hydration product types of cement prepared with GTs (C-GTs) and ordinary Portland cement (C-SS) were compared. X-ray diffraction (XRD), thermogravimetric (TG), and scanning electron microscope energy-dispersive spectroscopy (SEM-EDS) analysis techniques were used to study the mineralogical phases of the clinker and raw materials, hydration product types, and microtopography. The consistency, setting time, flexural strength and compressive strength values of the cement samples (C-GTs and C-SS), and burnability of the raw materials were also studied. The burnability analysis indicated that GTs provided a higher reactivity. The XRD results showed that the clinker phases of the C-GTs were C3S, C2S, C3A, and C4AF. The XRD, TG, and SEM-EDS results showed that the hydration products were flaky calcium hydroxide, rod-shaped ettringite, and granular C-S-H gels. Its compressive strength and flexural strength were, respectively, 30.4 MPa and 6.1 MPa at the curing age of 3 days and 59.1 MPa and 9.8 MPa at the curing age of 28 days, which were slightly higher than those of the C-SS. Furthermore, the results showed that the consistency, initial setting time, and final setting time for the two kinds of cement were similar, which further suggested that GTs could be used to prepare Portland cement.

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Physical and Adhesive Properties of Cyanoacrylate-Based β-TCP Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.330-332.419 ◽

2007 ◽

Vol 330-332 ◽

pp. 419-422 ◽

Cited By ~ 2

Author(s):

G.S. Lee ◽

Sang Bae Lee ◽

Doug Youn Lee ◽

Kyeong Jun Park ◽

S.O. Kim ◽

...

Keyword(s):

Compressive Strength ◽

Citric Acid ◽

Bond Strength ◽

Shear Bond Strength ◽

Setting Time ◽

Tissue Adhesive ◽

Adhesive Properties ◽

Composite Systems ◽

Filling Materials

Histoacryl® (N-butyl-2-cyanoacrylate) has been widely utilized as a tissue adhesive. The aim of this study was to evaluate the physical and adhesive properties of newly developed cyanoacrylate-based β-TCP composite systems. The β-TCP powder was modified on the surface with citric acid to make this material mixed with cyanoacrylate easily. The setting time of acidtreated β-TCP/ Histoacryl® systems was dramatically prolonged and the polymerization heat was significantly decreased compared to that of untreated β-TCP/Histoacryl® system. The shear bond strength of cyanoacrylate-based β-TCP composites decreased with addition of acid-treated β-TCP filler. The compressive strength of β-TCP/Histoacryl® composites increased strongly with increasing the amount of acid-treated β-TCP filler. The cytotoxicity of the β-TCP/Histoacryl® composites decreased with the increasing of the amount of added β-TCP. These results indicated that our novel β-TCP/Histoacryl® composites had the great potential to serve as adhesives or filling materials in the dental field.

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