scholarly journals Experimental Research on Material and Mechanical Properties of Rock-Like Filling Materials in Disaster Prevention of Underground Engineering

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Junwei Shi ◽  
Zhangliang Chen ◽  
Binbin Zheng
Keyword(s):  
Mechanical Properties ◽  
Mass Concentration ◽  
Setting Time ◽  
High Stress ◽  
Filling Material ◽  
Disaster Prevention ◽  
Underground Engineering ◽  
Filling Materials ◽  
Special Environment ◽  
Main Factor

Rock-like materials can be used as a filling material to improve the stability of underground engineering substantially. And the optimization of the rock-like material is an effective way to improve the performance of the filling material. Firstly, the AHP-FUZZY comprehensive optimization model was constructed for the complexity and fuzziness of the rock-like filling material ratio optimization. Secondly, according to the mechanical properties of rock-like filling materials under special environment (such as high temperature, high humidity, high stress, and high airtight) in old goaf, mechanical properties of rock-like filling materials were studied with the method of field core and laboratory test, which revealed the variation law of mechanical properties with time, and the regression equation between mechanical parameters and time was established with the method of least squares. Finally, the strength and deformation characteristics of rock-like filling materials were monitored by the monitoring and early warning technology. The results show that the optimal ratio of the rock-like filling materials is “E3”; that is, the cement content is 9%, the ash ratio is 2 : 5, and the mass concentration is 74%. The mass concentration is the main factor that affects the slump of the slurry, and the proportion of fly ash and coal gangue content directly affects the stratification and bleeding rate of the slurry. Reasonably increasing the ash and gangue ratio can significantly improve the workability and water retention of the rock-like filling materials. Also, the amount of composite cementitious material is the main factor that affects the setting time and the strength of the rock-like material. What is more, the special environment in gob is good for each chemical reaction fully in rock-like filling materials and strengthens the gelling property of deformation resisting capability, which can be a benefit for disaster prevention of underground engineering.

scholarly journals Investigation of the Sedimentation Property of Backfill Material on the Basis of Rheological Test: A Case Study of Iron Tailings

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Yong Wang ◽  
Aixiang Wu ◽  
Lianfu Zhang ◽  
Hongjiang Wang ◽  
Fei Jin
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Mass Concentration ◽  
Filling Material ◽  
Quantitative Characterization ◽  
Filling Materials ◽  
Characterization Studies ◽  
Rheological Test ◽  
Sedimentation Property

Sedimentation of filling materials could cause pipe blocking accident in mines. However, few quantitative characterization studies have investigated the sedimentation characteristics of filling materials. In this study, the sedimentation property of iron tailings with a cement-sand ratio of 1 : 4 and mass concentration of 73%∼82% was investigated based on rheology measurements. Results showed that shear stress increased as shear rate rose from 0 s−1to 120 s−1. The shear stress increased as the filling material concentration increased as well. However, when the shear rate was reversed from 120 s−1to 0 s−1, the shear stress presented an increase-constant-decrease change pattern as the mass concentration increases in the rheological curve. Accordingly, the sedimentation performance of iron tailings filling material was divided into three types: intense sedimentation (the ascending rheological curve) in the mass concentration range of 73%∼76%, slight sedimentation (the constant rheological curve) in the mass concentration range of 77%∼79%, and almost no sedimentation (the descending rheological curve) in the mass concentration range of 80%∼82%. The associated mechanism involving slurry mass concentration-rheological curves-sedimentation performance was illustrated. A correlation between the pipeline rheology and filling material sedimentation performance was established, which provides a practical guide to avoid pipeline blocking while transporting the filling material.

scholarly journals Microstructure and Mechanical Properties of 34CrNiMo6 Steel Repaired by Friction Stir Processing

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 279 ◽  
Author(s):  
Zhongwen Wu ◽  
Chunping Huang ◽  
Fencheng Liu ◽  
Chun Xia ◽  
Liming Ke
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Processing ◽  
Steel Structures ◽  
Optical Microscope ◽  
Filling Material ◽  
Welding Wire ◽  
Friction Stir ◽  
Filling Materials ◽  
Microstructure And Mechanical Properties ◽  
34Crnimo6 Steel

Repairing damaged parts using proper repairing methods has become an important means to reduce manufacturing and operational costs and prolong the service life of 34CrNiMo6 steel structures. In the conventional fusion repairing method, welding wire and powder are often used as filling materials. Filling materials are often expensive or difficult to find. Some metallurgical issues (such as solidification crack, higher distortion) were also found with these methods. At the same time, most of the equipment that requires welding wire and powder is expensive. In this study, a new method based on friction stir processing (FSP) was successfully employed to repair 34CrNiMo6 steel, using a block as filling material. Filling blocks are much cheaper than conventional fusion repair consumables. As a result of solid-state repair, this method can also avoid the metallurgical issues of fusion repair. The microstructure and mechanical properties of the repaired samples were investigated using OM (Optical Microscope), SEM, EDS (Energy Dispersive Spectroscopy), XRD, and a Vickers hardness electronic universal tensile tester. The results showed that 34CrNiMo6 steel was successfully repaired by this method, with no defect. Tensile tests showed that the maximum ultimate strength (UTS) was 900 MPa and could reach 91.8% of that of the substrate. The fracture mode of the tensile samples was ductile/brittle mixed fracture. Hence, the repairing method based on FSP appears to be a promising method for repairing castings.

scholarly journals Influential Factors in Transportation and Mechanical Properties of Aeolian Sand-Based Cemented Filling Material

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 116 ◽  
Author(s):  
Nan Zhou ◽  
Haobin Ma ◽  
Shenyang Ouyang ◽  
Deon Germain ◽  
Tao Hou
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Cement Content ◽  
Ash Content ◽  
Influential Factors ◽  
Filling Material ◽  
Aeolian Sand ◽  
Early Hydration ◽  
Filling Materials ◽  
Slag Content

Given that normal filling technology generally cannot be used for mining in the western part of China, as it has only a few sources for filling gangue, the feasibility of instead using cemented filling materials with aeolian sand as the aggregate is discussed in this study. We used laboratory tests to study how the fly ash (FA) content, cement content, lime–slag (LS) content, and concentration influence the transportation and mechanical properties of aeolian-sand-based cemented filling material. The internal microstructures and distributions of the elements in filled objects for curing times of 3 and 7 days are analyzed using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The experimental results show that: (i) the bleeding rate and slump of the filling-material slurry decrease gradually as the fly ash content, cement content, lime–slag content, and concentration increase, (ii) while the mechanical properties of the filled object increase. The optimal proportions for the aeolian sand-based cemented filling material include a concentration of 76%, a fly ash content of 47.5%, a cement content of 12.5%, a lime–slag content of 5%, and an aeolian sand content of 35%. The SEM observations show that the needle/rod-like ettringite (AFt) and amorphous and flocculent tobermorite (C-S-H) gel are the main early hydration products of a filled object with the above specific proportions. After increasing the curing time from 3 to 7 days, the AFt content decreases gradually, while the C-S-H content and the compactness increase.

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

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.

FEM Analysis of Lower Premolar Root Canal Filling

2011 ◽  
Vol 183 ◽  
pp. 17-24
Author(s):  
Witold Bojar ◽  
Witold Walke
Keyword(s):  
Mechanical Properties ◽  
Root Canal ◽  
Positive Influence ◽  
Composite Resins ◽  
Human Tooth ◽  
Filling Material ◽  
Root Canal Filling ◽  
Filling Materials ◽  
Effective Seal ◽  
Lower Premolar

Materials utilizing dentin adhesive technology were developed to provide more effective seal of a root canal. The combined use of new bondable root filling materials and self-adhesive sealers may increase the fracture resistance of filled canals. The null hypothesis of a positive influence on tooth biomechanics by a modern root canal filling material was tested in this study. In order to determine the strength characteristics of the analyzed endodontically treated human tooth the FEM (finite element method) was applied. Lower premolar was used to create a three dimensional model. Its canal was obturated using vertical compaction technique, gutta-percha and resin sealer, access opening was filled with composite resins. Strain analysis of the several elements of the tooth restoration does not allow attributing positive influence of contemporary obturating materials on mechanical properties of root canal dentin. Hypothetically, such an influence would have a filling material with comparable to dentin modulus of elasticity and flexural strength. It was also stated that loading the tooth with 250 N had an effect on increasing the tensions on the interface between filling material – sealer – canal wall. The stresses exceeded 4 MPa, reaching in extreme areas 10 MPa, what practically outweigh adhesion strength of modern root canal sealers. This phenomenon may provoke detachment of a filling from canal walls and therefore led to bacterial leakage. Results of this biomechanical analysis of the endodontically treated human premolar are valuable for a proper evaluation of mechanical properties of modern endodontic filling materials.

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.

scholarly journals Surface topography and mechanical properties of flax fibres modified glass ionomer restorative materials

2015 ◽  
Vol 1 (1) ◽  
pp. 82
Author(s):  
Ensanya Ali. Abou Neel ◽  
Wojciech Chrzanowski
Keyword(s):  
Mechanical Properties ◽  
High Stress ◽  
Surface Hardness ◽  
Biological Properties ◽  
Glass Ionomer ◽  
Force Microscopy ◽  
Flax Fibres ◽  
Filling Materials ◽  
Atomic Force ◽  
Stiffness Map

Objectives: Regardless of the excellent adhesive and biological properties of glass ionomer cements (GICs), their poor mechanical properties and abrasion resistance limit their application to non-load bearing areas. This study aimed to investigate the effect of flax fibres incorporation on surface and mechanical properties of GIC filling materials. Methods: Short chopped flax fibres were randomly incorporated into GIC at 0, 0.5, 1, 2.5, 5 and 25 wt%. Surface hardness, distribution of different phases, stiffness map, phase separation and uniformity of the material were investigated. Results: Addition of flax fibres produced no significant change in Vicker hardness number of GIC. Qualitative imaging using atomic force microscopy showed the presence of a single phase in GIC, while biphasic structure was observed for flax fibres modified GICs (FFMGICs). For all tested formulations, the flax fibres, however, were uniformly distributed and well integrated within the GIC matrix without any visible interfacial separation. Incorporation of flax fibres was associated with a significant increase in surface roughness and stiffness. The roughness values obtained for all tested formulations, however, are far below the threshold values for bacterial adhesion and plaque accumulation. Conclusions: Flax fibres modified GICs could be potentially used in high stress bearing areas.  

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 Effects of Steel Fiber Percentage and Aspect Ratios on Fresh and Harden Properties of Ultra-High Performance Fiber

2021 ◽  
Vol 2 (3) ◽  
pp. 501-515
Author(s):  
Rajib Kumar Biswas ◽  
Farabi Bin Ahmed ◽  
Md. Ehsanul Haque ◽  
Afra Anam Provasha ◽  
Zahid Hasan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
High Performance ◽  
Steel Fiber ◽  
Setting Time ◽  
Fiber Reinforced Concrete ◽  
Future Research ◽  
Manufacturing Cost ◽  
Aspect Ratios ◽  
High Performance Fiber

Steel fibers and their aspect ratios are important parameters that have significant influence on the mechanical properties of ultrahigh-performance fiber-reinforced concrete (UHPFRC). Steel fiber dosage also significantly contributes to the initial manufacturing cost of UHPFRC. This study presents a comprehensive literature review of the effects of steel fiber percentages and aspect ratios on the setting time, workability, and mechanical properties of UHPFRC. It was evident that (1) an increase in steel fiber dosage and aspect ratio negatively impacted workability, owing to the interlocking between fibers; (2) compressive strength was positively influenced by the steel fiber dosage and aspect ratio; and (3) a faster loading rate significantly improved the mechanical properties. There were also some shortcomings in the measurement method for setting time. Lastly, this research highlights current issues for future research. The findings of the study are useful for practicing engineers to understand the distinctive characteristics of UHPFRC.

scholarly journals Utilization of Solid Waste from Brick Industry and Hydrated Lime in Self-Compacting Cement Pastes

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1109
Author(s):  
Mati Ullah Shah ◽  
Muhammad Usman ◽  
Muhammad Usman Hanif ◽  
Iqra Naseem ◽  
Sara Farooq
Keyword(s):  
Mechanical Properties ◽  
Solid Waste ◽  
Manufacturing Industry ◽  
Setting Time ◽  
Hydrated Lime ◽  
Pozzolanic Reaction ◽  
Early Age ◽  
Cement Pastes ◽  
Brick Powder ◽  
High Degree

The huge amount of solid waste from the brick manufacturing industry can be used as a cement replacement. However, replacement exceeding 10% causes a reduction in strength due to the slowing of the pozzolanic reaction. Therefore, in this study, the pozzolanic potential of brick waste is enhanced using ultrafine brick powder with hydrated lime (HL). A total of six self-compacting paste mixes were studied. HL 2.5% by weight of binder was added in two formulations: 10% and 20% of waste burnt brick powder (WBBP), to activate the pozzolanic reaction. An increase in the water demand and setting time was observed by increasing the replacement percentage of WBBP. It was found that the mechanical properties of mixes containing 5% and 10% WBBP performed better than the control mix, while the mechanical properties of the mixes containing 20% WBBP were found to be almost equal to the control mix at 90 days. The addition of HL enhanced the early-age strength. Furthermore, WBBP formulations endorsed improvements in both durability and rheological properties, complemented by reduced early-age shrinkage. Overall, it was found that brick waste in ultrafine size has a very high degree of pozzolanic potential and can be effectively utilized as a supplementary cementitious material.

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