scholarly journals Numerical investigation on rigid and flexible pipelines embedded in granular and self-compacting materials

2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Khalid Abdel-Rahman ◽  
Tim Gerlach ◽  
Martin Achmus
Keyword(s):  
Numerical Model ◽  
Material Behavior ◽  
Filling Material ◽  
Soil System ◽  
Advantages And Disadvantages ◽  
Filling Materials ◽  
Soil Cement ◽  
Flowable Fill ◽  
Low Strength ◽  
Coulomb Failure Criterion

Abstract Self-compacting filling material or controlled low-strength material (CLSM) is a cementitious material which is liquid during filling, and it is used primarily as backfill, e.g., in trenches. Several products are currently used as CLSM such as flowable fill, controlled density fill, flowable mortar and low-strength plastic soil–cement. The low-strength requirement is necessary to allow for future excavation of CLSM. A two-dimensional numerical model was developed using the finite element system ABAQUS. In this model, the material behavior of granular soil and CLSM is described using an elasto-plastic constitutive model with Mohr–Coulomb failure criterion. Rigid and flexible pipes were modeled once embedded in sandy soil and once embedded in self-compacting material. The numerical model allows the modeling of the effect of hardening process on the overall behavior of the pipe–soil system. The main objective of this study is to investigate the behavior of rigid and flexible pipelines embedded in CLSM as a filling material numerically and to show advantages and disadvantages in comparison with the presently widely used filling materials like sand.

scholarly journals Root canal filling materials in primary teeth - review

Folia Medica ◽  
2021 ◽  
Vol 63 (5) ◽  
pp. 657-662
Author(s):  
Maria Shindova
Keyword(s):  
Antimicrobial Activity ◽  
Root Canal ◽  
Primary Teeth ◽  
Filling Material ◽  
Root Canal Filling ◽  
Advantages And Disadvantages ◽  
Dental Tissues ◽  
Filling Materials ◽  
Root Canal Filling Materials ◽  
Endodontic Infections

Inadequate treatment of endodontic infections in primary teeth results in a loss of а deciduous tooth or abnormality in the development of hard dental tissues of the permanent successor. The main goal is to maintain the integrity and health of the primary tooth until their physiological exfoliation. The success of the endodontic treatment depends on the antimicrobial activity of the root canal filling material that contributes to the elimination or reduction of the microbial infection of the root canal system. The aim of this article is to systematically review the contemporary scientific literature concerning the root canal filling materials used in primary teeth. A critical evaluation of the antimicrobial activity, as well as the advantages and disadvantages of the investigated materials, has been made. Knowledge of the composition and characteristics of the available obturating materials is a useful advantage to dentists to address the functional problems associated with endodontic infections in very young patients. Future studies should also seek and compare the long-term effects of the use of traditional and alternative intracanal materials.

scholarly journals The Materialization Characteristics and Ratio of a New Soil Paste Filling Material

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Zhi Wang ◽  
Weijian Yu ◽  
Fangfang Liu
Keyword(s):  
Strength Test ◽  
Red Soil ◽  
Filling Material ◽  
Test Results ◽  
Hydration Products ◽  
Hydration Mechanism ◽  
Filling Materials ◽  
Xrd Diffraction ◽  
Soil Cement ◽  
The Cost

In this paper, the research background is the filling and mining of the landscape mineral paste body in Baixian State, Guangxi, China. The strength test of the new paste filling material is carried out by the materials of coal zircon, red soil, and cement, the best ratio between the materials is obtained, and the hydration mechanism of the new paste filling material is studied by XRD diffraction instrument and SEM (scanning electron microscopy) test. The types of hydration products and microstructure forms of filling materials in different age periods are revealed. The test results show that the optimal ratio of the new paste filling material in the coal mine is the quality ratio of coal zircon: red soil: cement as 6 : 2 : 1, and the slurry concentration is 80%, which can not only meet the transportation requirements required by the filling process but also reduce the cost of filling, and with the extension of the maintenance age, the filling material produces more gel products, and the overall structure is more encrypted.

Tissue Reaction to Subcutaneous Implantation of SuperEBA (Reinforced Zinc Oxide Cement) Used as Root-End Filling Material: A Histological Study in Rats

2016 ◽  
Vol 695 ◽  
pp. 247-251
Author(s):  
Alexandru Andrei Iliescu ◽  
Cristian Marian Petcu ◽  
Ileana Cristiana Petcu ◽  
Irina Maria Gheorghiu ◽  
Andrei Iliescu ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Histological Study ◽  
Tissue Reaction ◽  
Tissue Response ◽  
Successful Outcome ◽  
Filling Material ◽  
Clinical Value ◽  
Filling Materials ◽  
Retrograde Filling ◽  
Specific Tissue

The retrograde filling is a critical step to a successful outcome of the endodontic surgery. Despite the progress in the technology of novel root-end filling materials, zinc oxide-eugenol cement superEBA is still preserving its clinical value on long-term basis. The study aimed to reconsider the tissue response to the initial irritating effect of this material. Silicon tubes filled with superEBA were subcutaneously implanted for 120 days in white Wistar rats which were afterwards sacrificed. The connective tissue surrounding the superEBA implants revealed fibroblast proliferation and a definite reparatory process without inflammatory reaction. A non-specific tissue healing in progress around the implants, without calcifications, necrosis, and apoptosis was also described after 4 months. SuperEBA proved on animal model that its cytotoxicity is reducing gradually in time until no adverse reaction is observed. The reduced content in eugenol compared to other surgical zinc oxide cements and the benefic effect of o-ethoxybenzoic acid are the support to reconsider SuperEBA as a biocompatible retrograde filling material.

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 Influence of Crack Geometry on Dynamic Damage of Cracked Rock: Crack Number and Filling Material

2020 ◽  
Vol 11 (1) ◽  
pp. 250
Author(s):  
Feili Wang ◽  
Shuhong Wang ◽  
Zhanguo Xiu
Keyword(s):  
Energy Absorption ◽  
Split Hopkinson Pressure Bar ◽  
Mineral Exploration ◽  
Damage Variable ◽  
Filling Material ◽  
Hopkinson Pressure Bar ◽  
Filling Materials ◽  
The Stability ◽  
Pressure Bar ◽  
Dynamic Damage

The dynamic damage of cracked rock threatens the stability of rock structures in rock engineering applications such as underground excavation, mineral exploration and rock slopes. In this study, the dynamic damage of cracked rock with different spatial geometry was investigated in an experimental method. Approximately 54 sandstone specimens with different numbers of joints and different filling materials were tested using the split Hopkinson pressure bar (SHPB) apparatus. The energy absorption in this process was analyzed, and the damage variable was obtained. The experimental results revealed that the dynamic damage of cracked rock is obviously influenced by the number of cracks; the larger the number, the higher the energy absorption and the bigger the dynamic damage variable. Moreover, it was observed from the dynamic compressive experiments that the energy absorption and the dynamic variable decreased with the strength and cohesion of the filling material, indicating that the filling material of crack has considerate influence on the dynamic damage of cracked rock.

scholarly journals Safety and Effectiveness of Additional Apical Preparation using a Rotary Heat-treated Nickel–Titanium file with Larger Diameter and Minimum Taper in Retreatment of Curved Root Canals

2021 ◽  
Author(s):  
Jader Camilo Pinto ◽  
Fernanda Ferrari Esteves Torres ◽  
Airton Oliveira Santos-Junior ◽  
Marco Antonio Hungaro Duarte ◽  
Juliane Maria Guerreiro-Tanomaru ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Continuous Wave ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Filling Material ◽  
Root Canals ◽  
Filling Materials ◽  
Heat Treated ◽  
Before And After ◽  
Curved Root Canals

Abstract Objective The aim of this study was to investigate the effect of additional apical preparation using the ProDesign Logic (PDL) 50/.01 rotary heat-treated nickel–titanium (NiTi) file with a larger diameter and minimal taper for retreatment of curved root canals. Materials and Methods Mesial curved root canals of 12 mandibular molars were prepared using PDL 25/.06 and filled using the continuous wave of condensation technique and AH Plus sealer. After retreatment using ProDesign S (PDS) 25/.08, PDL 25/.06 and PDL 35/05, a complementary procedure was performed with PDL 50/.01. Microcomputed tomography (micro-CT) scanning was performed before and after retreatment procedures. The cyclic fatigue resistance of unused PDS 25/.08, PDL 25/.06, PDL 35/.05 and PDL 50/.01 instruments (n = 12) was evaluated in a stainless-steel device. Statistical Analysis Data on the volumes of the root canals and the remaining filling materials were submitted to the paired t-test. Cyclic fatigue resistance data was submitted to one-way ANOVA and Tukey’s tests (α = 0.05). Results Use of PDL 50/.01 decreased the remaining filling materials in the apical third (p < 0.05). The root canal volume was similar in the cervical and middle thirds before and after preparation using PDL 50/.01 (p > 0.05). PDL 50/.01 presented the highest cyclic fatigue resistance (p < 0.05). Conclusions Use of the PDL 50/.01 instrument as an additional apical preparation for retreatment of curved root canals improved filling material removal in the apical third, while maintaining the dentin in the cervical and middle thirds. In addition, PDL 50/.01 presented high-flexural resistance.

Mechanical response of marble epistyles under shear: numerical analysis using an experimentally validated model

2018 ◽  
Vol 27 (3-4) ◽  
Author(s):  
Ermioni D. Pasiou ◽  
Stavros K. Kourkoulis
Keyword(s):  
Numerical Model ◽  
Stress Field ◽  
Mechanical Response ◽  
Specific Problem ◽  
Shear Loading ◽  
Filling Material ◽  
Experimental Protocol ◽  
Loading Mode ◽  
Traditional Design ◽  
Simple Contact

AbstractThe mechanical response of the restored “connections” of the epistyles of the Parthenon Temple on the Acropolis of Athens is studied assuming that the interconnected epistyles are under shear loading mode. The study is implemented by taking advantage of a numerical model, properly validated on the basis of the data of a recent relative experimental protocol. The main difficulty while studying the specific problem is the co-existence of three materials of completely different mechanical behaviors, i.e. the brittle marble of the epistyles, the ductile titanium of the connector and the cement-based material filling the grooves of the marble in which the connector is placed. The interfaces of this three-material-complex are simulated as simple contact with friction, the coefficient of which is, also, experimentally determined. Taking advantage of the data provided by the numerical model the stress field developed in the connector and the surrounding marble volume is described. Moreover, the forces imposed by the connector on the surface of the groove are quantitatively determined. Furthermore, the model permits a quantitative comparison between the mechanical response of the interconnected epistyles in the presence or in the absence of the “relieving space”. It is definitely concluded that the alternative design of the “connections”, according to which a small portion of the connector’s web is left uncovered by the filling material (relieving space), offers serious advantages against the traditional design, in the direction of reducing the intensity of the stress field developed in the marble volume surrounding the connector, thus, contributing to the protection of the authentic building material of the monument in the case of overloading of the epistyles.

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.

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