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In order to reduce the cost of roadside filling and ensure the stability of the retained roadway system, the 150202 fully mechanized mining face of Shenlei Coal Mine is taken as the background, and the roadside filling body is made of coal gangue and fly ash as the base material, through orthogonal experiments, theoretical analysis, numerical simulation, on-site measurement and other research methods, the optimal ratio of filling materials and the laws of yield stress and deformation of roadway surrounding rock with different filling widths are studied. The results show that the optimal ratio of gangue filling body is water cement ratio 1∶1.85, fly ash replacement cement ratio of 20%, fine coarse aggregate ratio of 35∶65, and sodium silicate content of 6%; the larger the width of the roadside filling body next to the gob-side entry retaining, the lower the deformation of the surrounding rock and the vertical stress of the coal wall; by comprehensively comparing the stress and displacement of surrounding rock under different widths, it is concluded that the reasonable width of the roadside filling body next to gob-side entry retaining is 1.2 m.

The utilization of oil shale ash in developing environmentally sustainable filling materials for subterranean mines presents a promising ecological approach, albeit with typically low ash content. In this study, the filling material was prepared by adding oil shale ash and slag. The study examines the physical and mechanical properties of filling materials predominantly composed of oil shale ash slag, sourced from the Baoming open-pit mine in Jimusar, Xinjiang. Comprehensive testing and analysis are conducted to examine the chemical composition, mineral composition, and particle grading of oil shale ash, cement, and fly ash. The research prepared 45 cubic specimens measuring 50 mm × 50 mm × 50 mm and analyzed their mechanical responses under uniaxial compression conditions, employing varying dosages of ash, cementitious materials, and water as critical variables. The results indicate that the primary constituents of oil shale ash are silica (SiO2) and aluminum trioxide (Al2O3). When the oil shale ash content ranges from 60 to 70%, with a cement-fly ash ratio of 7:1 and a water content of 11%, the filling material attains its highest average compressive strength of 16.37 MPa at 28 days. Furthermore, increased cement content in the cementitious material correlates with higher compressive strength in the filling material. This research underscores the potential of oil shale ash–based green mining filling materials to restore goaf. [ABSTRACT FROM AUTHOR]

To study the effect of various loading rates and aggregate particle size gradations on the mechanical properties and fracture characteristics of cemented waste rock backfill, cemented waste rock backfills with various aggregate particle size gradations were conducted by uniaxial compression tests to analyze the mechanical properties with various loading rates, and the development and evolution of cracks inside the cemented waste rock backfill were studied with the help of acoustic emission system. The results show that the uniaxial compressive strength and elastic modulus of cemented waste rock backfill increased linearly with the increase of loading rate; with the increase of aggregate grading index, the uniaxial compressive strength and elastic modulus of cemented waste rock backfills display a rule of growth before decreasing; the damage mode of the specimen gradually changed from tensile damage to shear damage with the increase of aggregate grading index and loading rate, and the damage degree increased and the integrity decreased; the internal cracking of the specimen gradually changed from tensile damage to shear damage, and the damage degree increased. The development of cracks in the specimen is divided into four stages: compression-density stage, elastic deformation stage, stable crack expansion stage and unstable crack expansion stage.

Mine green filling plays an important role in the protection of ecological environment. In order to explore the development trend of green filling technology in mines at home and abroad in recent years, this paper uses CiteSpace to analyze the literatures on CNKI and WOS from 2004 to 2022, and studies the status quo and trend of green filling technology in mines by the number of publications, institutions, authors and keywords. The research shows that the attention on green filling technology in mines at home and abroad is increasing year by year, and China is in a leading position in this field. Its research focuses on filling materials, filling process, filling effect and environmental impact, etc. Data mining, acid mine drainage and edge computing are hot fields. The green filling technology in mine has a broad development prospect, but it still needs to solve the problems of material, process equipment and effect detection and evaluation to improve the level and effect of filling.

Objectives: To compare the operative time and presence of air voids on Class II restorations fabricated by dental practitioners with 1 to 5 years of experience using incremental and bulk-filling techniques. Method and materials: Four techniques were evaluated: incremental, bulk-filling, bulk-filling with heated composite, and snowplow technique. Standardized mandibular first molars with a MOD (mesial, occlusal, and distal) cavity were used. Voluntary operators made two restorations using each technique and the time required for each restoration was recorded. The restorations were scanned by micro-computed tomography to calculate the volume of the restoration occupied by air voids. The "operative time" and "volume of air voids" were analyzed individually by two-way ANOVA and Tukey HSD post hoc (a = .05) for the factors operator and insertion technique. A correlation between "operative time" and "volume of air voids" was evaluated using Pearson coefficient (a = .05). Results: The incremental technique required significantly longer time, yet no differences were observed between the bulk-filling techniques. There were no significant differences between techniques regarding the volume of air voids. A significant, but weak, and inverse linear correlation (P = .0059; r = -.29; r2 = 8.41%) was found between the operative time and volume of air voids. Conclusion: There were no significant differences in the volume of air voids among the evaluated techniques, although bulk-filling techniques required a shorter operative time. Hence, implementing bulk-filling techniques by dental schools and restorative dental practitioners with different levels of expertise may reduce chair time and produce a volume of air voids similar to the incremental technique. [ABSTRACT FROM AUTHOR]

A finite element analysis (FEA) study was performed to determine whether the material of apical barrier used for root apexification and/or the use of canal reinforcement affect the stress distribution in an endodontically treated immature permanent tooth in order to infer in which clinical scenarios a fracture is more likely to occur based on the ultimate tensile strength threshold of dentin. An extracted human immature mandibular premolar was selected as the reference model and scanned by micro-computed tomography (micro-CT). The digital model was segmented and converted to STL (Standard Tessellation Language) using Simpleware Scan-IP and exported in IGES (Initial Graphics Exchange Specification) to Ansys 19. Six experimental models were designed with different combinations of composite, mineral trioxide aggregate (MTA), and Biodentine (BIO). Using FEA, a static 300 N load at a 135 angle with respect to the axis of the tooth was applied to each model and von Mises stress values (MPa) were measured at the sagittal, apical 8-mm, 5-mm, 2-mm, and 1-mm levels. In all regions examined, the control (NT model) had lower stress in the root compared WITH experimental models. At the mid-root level, models with composite, MTA, and BIO reinforcement exhibited lower stresses in the root dentin than those with pulp or gutta-percha. BIO models had equal or greater average von Mises stress values than those of MTA models in all regions. Both, MTA and BIO, caused increases in stress of surrounding root dentin, with BIO causing a greater increase than MTA. Stress distribution in immature permanent teeth treated by apexification is affected by the types of materials used. Root dentin's stress was lower when the mid-root canal was reinforced by composite, MTA, or BIO, which provided similar stress reduction to the root dentin. MTA is a more favorable apical barrier material from a mechanical standpoint because it induces less stress on apical root dentin than BIO. [ABSTRACT FROM AUTHOR]

Objectives: To test if cigarette smoke (CS) causes discoloration of enamel, dentin, and composite resin restorations and induces color mismatch between dental hard tissues and the restorations, and to compare the findings with the effects of aerosol generated by the tobacco heating system (THS) 2.2. Method and materials: Twenty-two human premolars were prepared with Class V cavities restored with Filtek Supreme Ultra (3M Espe) composite resin. Teeth were divided into two groups and exposed to either CS from 20 reference cigarettes (3R4F) or aerosol from 20 THS 2.2 tobacco heat sticks 4 days a week for 3 weeks. CIE L*a*b* color was assessed before and after exposure and brushing at 1, 2, and 3 weeks. Color match, marginal discoloration, marginal integrity, and surface texture of the Class V restoration were assessed according to a modified US Public Health Service (USPHS) criterion. Results: Marked discoloration of enamel and dentin was observed following 3 weeks of CS exposure (ΔE = 8.8 ± 2.6 and 21.3 ± 4.4, respectively), and color mismatch occurred between the composite resin restorations (ΔE = 25.6 ± 3.8) and dental hard tissues. Discoloration was minimal in the enamel, dentin, and composite resin restorations in the THS 2.2 group, and no color mismatch was observed after 3 weeks of THS 2.2 aerosol exposure. Conclusion: CS causes significant tooth discoloration and induces color mismatch between dental hard tissues and composite resin restorations. Reducing or eliminating the deposits derived from tobacco combustion could minimize the impact of tobacco products on tooth discoloration. [ABSTRACT FROM AUTHOR]

In order to determine the pumping performance index of high-concentration tailings slurry in Gaofeng Mine, the pumping simulation of total tailings slurry with different mass concentrations, namely 86 %,84 %,83 %,81 %,and 79 %,was carried out by using two-phase particle flow mechanics theory. The results show that in the steady pipeline flow field, decreasing slurry concentration is beneficial to transportation fluidity, but when slurry concentration is low, the effect grows less obvious. In terms of the waste-to-tail ratio, 6∶4 or 7∶3 is recommended when the strength is satisfied. Further improvement of parameters may lead to a surge of erosion and silting. The research results provide a theoretical basis for the design of an underground pumping filling pipe network. [ABSTRACT FROM AUTHOR]

The choice of the material used to fill screw access channels in implant-supported prostheses depends, in most cases, on operator's preference, without considering the susceptibility of biofilm colonization. Therefore, the aim of this study was to determine and compare the total amount of biofilm formed on different materials used to fill screw access channels in implant abutments. For this propose, titanium implant analogs were attached on abutments and divided into 5 groups: positive control (no filling material); negative control (closed with resin); and filled with cotton, gutta-percha, or polytetrafluoroethylene (PTFE). The analogs with attached abutments were then immersed in a brain heart infusion medium containing Candida albicans (strain 10231 from American Type Culture Collection [ATCC]) and incubated aerobically at 37°C with gentle agitation. After 15 days, materials were removed, and total viable biofilm on each material was quantified by methyl tetrazolium reduction assay at 490 nm. All experiments were performed in triplicate. Data were processed by IBM SPSS Statistic software using 1-way analysis of variance and Bonferroni post hoc tests to analyze differences between groups, with an overall significance level of P <.001. A significant difference was observed between cotton and gutta-percha (P <.017) and between cotton and PTFE (P <.025). However, there was no statistical difference between gutta-percha and PTFE (P >.050). Thus, this in vitro experiment showed that gutta-percha and PTFE presented lower biofilm formation compared with cotton when used to fill screw access channels. These results can provide a basis for future clinical studies that can be a guide to decreasing the occurrence of gaps and bacterial growth inside the implant/abutment attachment site. In addition, controlled in vivo studies are necessary to confirm the clinical viability of findings of this study. [ABSTRACT FROM AUTHOR]

In recent years, Metal-Organic Frameworks (MOFs) have garnered significant attention for their potential in tetracycline (TC) removal. However, pure MOFs typically exist in powdered form and tend to aggregate in water, which greatly limits practical applications. To address this issue, a three-dimensional composite material was prepared by ZIF-67 grown onto cotton fibers (ZIF-67 0.50 @CF). This composite not only enhances adsorption capacity but also reduces the adsorption equilibrium time compared to most other adsorbents. ZIF-67 0.50 @CF boasts a BET specific surface area of 257.74 m²·g−1, with pores consisting mainly of mesopores and micropores. Moreover, ZIF-67 0.50 @CF exhibits excellent adsorption capabilities for TC across a broad pH range of 4–9 and displays notable resilience against environmental interference. The adsorption behavior of ZIF-67 0.50 @CF is more consistent with the Langmuir model, with a maximum adsorption capacity of 432.619 mg·g−1 for TC. Mechanistic research reveals that adsorption primarily involves chemical interactions (complexation, π-π stacking, and electrostatic interaction) and physical pore filling. Additionally, the favorable plasticity of ZIF-67 0.50 @CF allows it to be fabricated into various shapes for use as filling materials, exhibiting admirable TC removal performance in continuous flow adsorption experiments. [Display omitted] • Successful preparation of ZIF-67 0.50 @CF by in situ growth of ZIF-67 on cotton fibers. • Cotton fibers improve the adsorption properties of ZIF-67 0.50 @CF. • Adsorption mechanisms mainly include pore filling, electrostatic interaction, complexation, and π-π stacking. • Three-dimensional ZIF-67 0.50 @CF has good flexibility and easy separation from water. [ABSTRACT FROM AUTHOR]

A large amount of river silt is continuously dredged and usually dumped in landfills or oceans, resulting in land occupation and environmental pollution. Traditionally, cement-based materials are used to cement dredged river silt as building materials, which not only increases carbon dioxide emissions but also uses very little dredged silt. In order to realize the resource utilization of dredged river silt, microbial induced calcium carbonate precipitation (MICP) technology, which has the advantages of lower energy consumption, less environmental pollution and lower carbon emissions, is adopted to solidify the dredged river silt as roadbed materials in this paper. The unconfined compressive strength (UCS) test, calcium carbonate (CaCO3) content test and microstructure test are carried out to analyze the mechanical properties of the solidified dredged river silt. The test results show that the MICP mixing method can be employed to solidify loose dredged river silt into high-strength construction materials. The concentration of the cementation solution has a significant effect on the solidification effect, and the most reasonable concentration of the cementation solution is 1.5 mol/L. With the increase of treatment times, the pores in the soil are filled with CaCO3, and the UCS of the specimens after 10 times of treatment can reach 6.75 MPa with a relatively uniform CaCO3 content of 27.8 %. The main crystal form of CaCO3 is calcite, which can fill the pores and make the river silt particles cement as a whole, which is the main reason for the improvement of mechanical properties of dredged river silt.

Based on the actual situation of high cost of paste filling due to the drastic price increase of cement gelatinous materials, to reduce the filling cost, relevant research was carried out with industrial waste fluorine anhydrite as the main research object.A new type of paste filling material was studied by using waste rock, fluorine anhydrite, fly ash and quick lime as admixtures and supplemented with certain amount of additives.The optimal mixture ratio of materials was determined by slump, expansion rate tests and the paste were subjected to uniaxial, triaxial and SEM tests to analyze its macro and micro structures.The results showed that the loss rate of slump and expansion increased with the increase of mass concentration from 0 to 120 min, but the bleeding rate decreased gradually.The uniaxial compressive stress-strain curve of the fluorgypsum-based paste prepared by the optimal mixture ratio belonged to the elastic-plastic curve, which was up to 6-7 MPa. After uniaxial and triaxial compression tests, no large rupture surface appeared on the surface of the paste, and the stress-strain curve on longer showed peak stress with the increase of the surrounding rock pressure.The hydrates of the filling materials mainly included ettringite (Aft),hydrated calcium silicate gel (C-S-H) and calcium sulfate dehydrate (CaSO4·2 H2O). The preparation of fluorgypsum-based new paste filling materials had a far-reaching influence, which provided a guarantee for the realization of efficient, safe, green and sustainable mining. [ABSTRACT FROM AUTHOR]

In order to provide a technical basis for the subsequent concentration and utilization of the tailings treatment process in an iron ore mine, and to achieve the objectives of cost reduction and sustainable development, the settling concentration and settling capacity of a tailings slurry with an initial concentration of 40% in its natural state were tested in conjunction with the pumping supply concentration index of the beneficiation tailings slurry in a metal mine. The test results show that the iron ore tailings particles settle at an overall fast rate: basically, within 10 to 20 min they are able to reach or approach 85 to 99.5% of the final settling state-related index. During the settling process in the fixed container, at first, the clarified water at the top of the tailings slurry is very turbid. With the passage of time, the clarified water gradually becomes blurred and clear from turbidity, and the interface between the slurry and the water gradually becomes clearer. From the phenomena observed during the settling process and the test parameters such as the net increase in clear water and slurry variation, the maximum settling concentration and settling capacity indicators of 50% and 90% can be reached or approached in 5.5 to 7.25 and 10.5 to 15.5 min after settling, and the maximum settling concentration and settling capacity can be reached or approached in 10 to 20 min after the settling process. As the settling tests and observations continued, the relevant settling parameters basically reached the final settling state within the time period of 20 to 1440 min, during which the settling concentration of the tailing sand was 71.33 to 73.42% and the settling capacity was 1.85 to 1.91 g/cm3. It can be judged from the test results that the natural settling of the low concentration tailings slurry can meet the technical specifications required for the filling process, and that the natural settling and concentration of dewatering can save the costs of the relevant facilities and flocculation chemicals, and therefore has good technical and economic feasibility. [ABSTRACT FROM AUTHOR]

In order to solve the problems of ecological environment caused by the shortage of filling materials and solid wastes in the goaf of coal mine, the paper puts forward some suggestions to solve these problems, in the paper, influencing factors of paste filling body strength were analyzed, and sample strength of filling body was determined by orthogonal test, the correlation between the influence factors and the strength of the filling body was determined with grey relational analysis method, and an improved BP strength prediction model was built, in which the factors affecting the strength of solid waste paste filling are input layer and the strength of the filling body is output layer. The strength test data obtained from orthogonal test were used as training samples and test samples of the network, the fitting ability and generalization ability of network data were tested by analog simulation. Test results show that the established prediction model has fast convergence speed and high accuracy, and its prediction accuracy reaches 93.75%, which indicates accurate prediction of the filling body strength can be realized.

Dental resin materials have been widely used in the treatment of dental defects. However, the polymerization shrinkage of the resin materials tends to cause microleakage and accumulation of bacterial plaque, which leads to secondary dental caries. Endowing dental resin with antibacterial properties is an important way to solve this problem. Adding antibacterial agents to dental resin is the main method to give it antibacterial properties. Antimicrobial agents are mainly divided into three types: release type, non-release type and mixed type. In terms of antibacterial effects, the selection and addition of antibacterial agents will affect the antibacterial and mechanical properties of dental resin materials; and the long-term antibacterial effect of antimicrobial agents in the oral cavity remains to be verified; as antimicrobial agents or other environmental factors can lead to drug resistance and even dormant persistent bacteria. In recent years, researchers have been committed to improving the antibacterial effect by modifying antibacterial agents. The sustained release of antimicrobial agents via carriers is also the main research direction. This paper reviews the research progress on the antibacterial properties of dental resin materials.

Non-surgical endodontic retreatment is a reliable conservative option for managing post-treatment apical periodontitis. However, effective microbial control, based on the maximization of filling removal and disinfection protocols, is not yet predictable. Traditional gutta-percha solvents, which are indistinctively used for both the core and sealer filling materials, became obsolete due to unprecedented advances in endodontic technology. Nonetheless, microtomography, scanning electronic microscopy findings, and histobacteriological analysis tend to confirm the persistence of filling materials and the lack of association between root canal enlargement and superior disinfection. There is a controversy regarding the most suitable clinical protocols surrounding the shaping procedures and the supplementary disinfection steps. Based on the literature and the previous work of the team, the authors aimed to summarize the current knowledge regarding specific solvent formulations that target filling materials. Additionally, the advantage of an additional irrigation step to optimize disinfection was highlighted. This adjunctive procedure serves a dual role in the dissolution of filling materials, and in conferring an antibiofilm effect. Further research is needed to understand the novel contribution of these strategies upon clinical practice outcomes. [ABSTRACT FROM AUTHOR]

The identification of filling materials in an underground karst pipeline is highly important in karst hydrogeology and karst engineering geology; however, there is no suitable surface detection method to identify the common filling materials (such as clay, sand, water) in a buried karst pipeline. This study aimed to identify pipeline materials using the spectral induced polarization (SIP) method on the surface. We carried out experiments in the laboratory and field under a carbonate environment to test the validity of various IP parameters obtained from complex conductivity tomography for identifying pipeline materials. The gradient array was used to collect data in the study, and the Cole–Cole model was introduced. The data were processed using a two-step inversion method. Firstly, the conductivity magnitude and the phase during each frequency are inverted, and later the parameters of the Cole–Cole model are inverted according to the phase spectrum. The results indicate the differences in spectral characteristics of the phase inversion section, the imaginary conductivity inversion section, the Cole–Cole model parameter inversion section, and the Cole–Cole model parameter values (m, τ, c) can be used to distinguish clay-filled, sand-filled or water-filled karst. Of particular note is the τ parameter of the Cole–Cole model; the τ value of the water-filled pipeline can reach tens of seconds and shows strong contrast with surroundings in both the pilot physical model test and field test. The water richness of the medium may be closely related to the τ value, which could be a key parameter in identifying whether a karst pipeline is filled with water. A comparative analysis of all IP parameters could greatly improve the recognition of pipeline filling materials in the field. This work proposes a SIP method for high-resolution detection of near-surface karst pipelines. [ABSTRACT FROM AUTHOR]

Canal filling materials and techniques have been one of the most studied topics in Endodontics. A simple search using the mesh term "root canal filling" in PubMed revealed more than 11 000 articles, an impressive number that is much higher than "root canal disinfection" (5544 articles) or even the popular "root canal preparation" (8527 articles). The overriding importance attributed to root filling procedures is not merely intuitive. It derived from the appealing relevance given by the appearance of the white lines in common radiographs grounded on retrospective clinical data that had identified the quality of a root filling as one of the major causes of treatment failure (lack of healing). Since the publication of the Washington study, impressive efforts have been made for the release of new materials and techniques, as well as, for the development of a plethora of laboratory methods to assess the quality of root filling procedures. This narrative review aims to address and discuss the most relevant laboratory methods to assess the root canal filling. As filling quality improvements have not translated into higher success rates, as reported in longitudinal clinical studies, more than to deliver a simple methodology‐based review, this paper aims to present an in‐depth critical view on the assessment of laboratory methods used to study the filling materials and techniques. Recent data indicate that the long‐term dimensional stability/degradation over time of endodontic sealers plays a central role in the treatment outcome. In this context, laboratory methods should be developed focusing on predicting, at least to some degree, the long‐term clinical behaviour of root canal fillings, rather than simply ranking different materials or techniques. [ABSTRACT FROM AUTHOR]

Enhancement of Dielectric strength is an important issue to enhance power system reliability. Insulation filling such as Alumina Trihydrate (ATH) and Silicon dioxide (Sio2) are used to enhance the dielectric strength of polymer insulator. The paper proposes a mathematical model of dielectric strength considering different temperatures and filling percentages using neural network. Moreover, comparison of filling materials is carried out through this model. The comparison shows the superiority of ATH in enhancing the dielectric strength of the polymer. Also, the obtained model will help in getting the best filling concentration without needing to repeat the tests which can be considered as a techno-economical solution to enhance the dielectric strength. Finally, the curve fitting is used to get the dielectric strength model not only as a function of filling concentration percentage but also as a function of temperature. [ABSTRACT FROM AUTHOR]

Increasing the average age of the population as well as sports injuries, bone-related diseases, such as osteoporosis, rupture or damage to cartilage and bone tissues, and bone fractures, has dramatically increased the need for repair and joint replacement surgeries. Biocompatible materials that are used as prosthetic stabilizers and bone fillers in orthopedic surgery are known as injectable bone cement (IBCs). Available clinical IBCs, such as polymethyl methacrylate and calcium phosphate cement are the most important of these materials. This paper presents the most popular substances for medical use. Although this replacement procedure reduces the pain and restores joint function, it is associated with several drawbacks that limit its efficiency and effectiveness, and sometimes patients should undergo revision surgeries. Recently, the development of the next generation of IBCs, which are bioactive and degradable with good mechanical properties, is of great interest. For the long-term clinical performance in cement arthroplasty, the next generation of bone cement with far greater mechanical and biological properties than acrylic bone cement on the market is required. As a result, new approaches and formulas have been developed using various techniques from different disciplines. This study summarizes the challenges, developments, and recommendations for the future. For this purpose, various literature from databases, such as ScienceDirect, SpringerLink, PubMed, and so on were consulted from 2000 to 2020. [ABSTRACT FROM AUTHOR]

Red mud is a solid waste produced in the process of bauxite refining alumina, with high alkali content, and its treatment methods are mainly stacking and ocean dumping, which not only occupy a large amount of cultivated land and pollute land and water sources, but also have high safety risk. The preparation of red mud-based filling materials to fill the underground goaf can improve the utilization rate of mineral resources and reduce the harm of red mud to the environment, which has the effect of killing two birds with one stone. In view of the problems of low utilization rate of bayer red mud in mine filling system, low strength, bleeding and shrinkage in filling materials slurry with low concentration, the effects of the addition ratio of fly ash, desulfurization gypsum, lime and initiator on the early strength and volume stability were studied in this paper. Scanning electron microscope- energy dispersive spectroscope (SEM-EDS) and X-ray diffraction (XRD) were used to analyze the hydration mechanism of the filling materials. The results show that when the ratio of red mud to fly ash is 4∶6, the mechanical properties of the filling material are the best. Desulfurized gypsum promotes the formation of ettringite. Lime promotes the pozzolanic effect of fly ash. The composite activator can accelerate the hydration process of red mud and fly ash. All of this enhance the red mud backfill strength. The filling materials 28 d compressive strength is 3.35 MPa, and the initial and 60 min fluidity are above 200 mm. Microscopic test results show that the hydration products of hardened paste are ettringite, lawsonite, silica aluminate gel, which fill the pores and improve the strength of slurry. Through adding activator, activating red mud activity and designing low concentration filling material, it is the direction of mass and green utilization of red mud, desulfurization gypsum and other solid wastes. The utilization ratio of solid waste of red mud filling materials reaches 92%, no bleeding, no shrinkage, and has high economic value and environmental value.

In view of the coal spontaneous combustion accident caused by air leakage in the mine, this paper studied the foaming cement solidified filling material used for mine filling and plugging with cement as the base material, foaming agent, gypsum and polypropylene fiber as additives. Through the single factor test method, the optimized ratio of the main components affecting the compressive strength and expansion ratio of the foamed cement solidified filling material was determined as the water-cement ratio 0.5, the foaming agent content 1%, and the gypsum content 6%, polypropylene fiber 0.4%. Taking Cuimu Mine as the experimental background, through the design of reasonable and effective filling technology scheme, the 21303 wind tunnel in the lower part of 22306 working face of Cuimu Mine was filled. The test results show that the foamed cement solidified material effectively enhances the airtightness of the wind tunnel and the roadway.

Flashover voltage is considered one of the important factors affect the Power system reliability. Environmental conditions and filling of insulators are parameters should be considered in flashover voltage evaluation. In this work, laboratory studies are carried out on insulator with Alumina Trihydrate [ATH] filling at different concentration and different weather conditions to investigate the flashover voltage. The evaluation of flashover voltage is carried out at three conditions dry, wet and salt wet condition. In each test, four different lengths with different filling concentration are considered. Several curve fitting methods are used to obtain an equation of flashover voltage. The obtained equation first is only function of filling at different insulator lengths with approximately zero errors. Although the accuracy of this method, it gives flashover voltage only at discrete lengths. Thus, for continuous length validation the flashover is fitted again to be a function of both length and filling.

Poly(methyl methacrylate) (PMMA)‐based bone cements (BCs) can be defined as a family of materials that consist of powder and liquid phases which after mixing form a plastic paste that can self‐set once implanted in the human body. PMMA‐based BCs are easily molded and adapted to complex bone cavities or used in orthodontic applications to restore dental damage. The main advantages of the use of cement are the excellent primary fixation between bone and implant and, therefore, the faster recovery of the patient. Despite the initial success rate of implant fixation with BCs, they have some disadvantages such as local tissue damage due to exothermic polymerization reactions, mechanical mismatch between native bone and cement, lack of bone regeneration and bioactivity and poor mechanical properties which may cause the failure of the BCs. BCs are still considered as a top option for bone repair. Due to the disadvantages highlighted, research has focused on alternative materials used with PMMA‐based BCs. This review aims to critically review the BCs and emerging materials used in combination with PMMA‐based BCs. These materials include titania, apatite–wollastonite (A‐W), glass ceramic (GC) and hydroxyapatite (HA). The review discusses the properties of these materials and their pathway to clinical study. Among the various kinds of reinforcement, HA has been extensively used. So, in this review, we compare the effects of HA as reinforcement in PMMA‐based BCs. Upcoming study of PMMA‐based BCs should concentrate on trialing combinations of these reinforcing agents as this might improve beneficial characteristics. © 2020 Society of Industrial Chemistry [ABSTRACT FROM AUTHOR]

Purpose: To find out the most appropriate management scheme through the analysis and comparison of different inactivation methods and filling materials.Method: A systematic literature search was performed using the terms, anhydrous ethanol, phenol, hypertonic saline, cryotherapy, thermal therapy, bone reconstruction, GCTB, and etc., Selected articles were studied and summarized. The mechanism, clinical effects, and influence on bone repair of various methods are presented. Recent developments and perspectives are also demonstrated.Recent Findings: Compared to curettage alone, management of the residual cavity can effectively reduce the recurrence of giant cell tumours of bone. It is a complex and multidisciplinary process that includes three steps: local control, cavity filling, and osteogenic induction. In terms of local control, High-speed burring can enlarge the area of curettage but may cause the spread and planting of tumour tissues. Among the inactivation methods, Anhydrous ethanol, and hyperthermia therapy are relatively safe and efficient. The combination of the two may achieve a better inactivation effect. When inactivating the cavity, we need to adjust the approach according to the invasion of the tumour. Filling materials and bone repair should also be considered in management.

Leila Basir,1 Mashallah Khanehmasjedi,2 Azardokht Khosravi,3 Sahameh Ansarifar4 1Infectious and Tropical Diseases Research Center of Health Research Institute, Department of Pediatric Dentistry, School of Dentistry, Jundishapur University of Medical Sciences, Ahvaz, Iran; 2Department of Orthodoncy, Faculty of Dentistry, Jundishapur University of Medical Sciences, Ahvaz, Iran; 3Department of Microbiology, Faculty of Medicine, Jundishapur University of Medical Sciences, Ahvaz, Iran; 4Department of Pediatric Dentistry, School of Dentistry, Jundishapur University of Medical Sciences, Ahvaz, IranCorrespondence: Leila BasirInfectious and Tropical Diseases Research Center of Health Research Institute, Department of Pediatric Dentistry, School of Dentistry, Jundishapur University of Medical Sciences, PO Box 159, Ahvaz 15794-61357, IranEmail basir_l@yahoo.comBackground: The antiseptic property of root canal filling materials is very important for the removal of residual pathogens from root canals. The aim of the current study was to investigate the antimicrobial activity of mineral trioxide aggregate (MTA), calcium hydroxide (CH), Metapex, zinc oxide eugenol (ZOE), and CEM-cement.Materials and methods: Four standard bacterial strains including Staphylococcus aureus (ATCC 6538), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853), and Bacillus subtilis (ATCC 6633) and Candida albicans (ATCC 10231) were used. On five plates containing Brain Heart Infusion (BHI) agar, five cavities were made. Then, the plates were cultured by 0.1 mL of bacterial suspension with a concentration of 0.5 McFarland. Afterwards, the cavities were filled with the tested materials and were incubated at 37 °C for 24, 48, and 72 hrs. Diameters of microbial inhibition zones were then measured.Results: The highest mean diameter of growth inhibition zones was observed around ZOE and then CH and CEM-cement. According to the Kruskal-Wallis test, there was a significant difference among the tested groups (P

The aim of this study is to prepare a low cost and high strength filling material.Coal gangue is aggregate.Fly ash,desulfurization gypsum and silicium-calcium slag are cementing materials.The uniaxial compressive strength,slump and slump flow of the specimen were measured to investigate the mechanical properties and the influence of each component.The result shows that desulphurization gypsum content and silicium-calcium slag have a strong gelation effect in certain amount range.With the increase of content of fly ash,the initial strength of filling material increases slowly.The content of fly ash should be controlled less than 6.67%.The mixing of fly ash and silicium-calcium slag could activate cementious properties of silicium-calcium slag performance.The optimum mass ratios of coal gangue,fly ash,desulfurization gypsum,silicium-calcium slag and cement are 70:6:3:12.5:8.5.The conclusion is verified by response surface method,and the experimental results are consistent with the prediction.

Structure of vehicle body is designed to absorb kinetic energy,transform impact force and keep survival space during crash. Light weight design of BIWcan realize better power performance and fuel economy,decrease exhaust emission. In this paper,collision of vehicle body structure is decomposed into axial crushing and transverse bending. Thin walled structure’s ability inenergy absorption and bending resistanceis researched,which is based on high strength steel and different filling materials. After applied the research conclusion in a SUV’s body optimization,the crash simulation result shows that it improved passive safety and reduced body weight effectively.

Background: The currently used subcutaneous fillers are not effective enough. The use of autologous tissues or cells will reduce immune rejection and increase the stability of the fillers, while increasing the absorbability of filling materials. To establish a durable and safe filling material, we herein combined acellular dermal matrix (ADM) with autologous dermal cells and tested the performance of this matrix in wound healing and shaping. Methods: To prepare the ADM, stratified skin was obtained from the back of two New Zealand rabbits and decellularized to obtain ADM. The ADM was ultrasonically mixed with as-prepared autologous dermis in vitro. The mixture was injected as a subcutaneous filler into the back area of 20 New Zealand rabbits. In this procedure, different concentration ratios of the mixture were injected, and the volume change of the filler was measured and categorized into five groups. At 4 months and 8 months after filling, samples were obtained for quantitative evaluation of the thickness and vessel density, as well as qualitative evaluation of colonization. Results: Examination of the ADM conformed that the matrix had no cells. ADM and the prepared autologous dermis were evenly mixed, and the filler was gradually absorbed. The comprehensive evaluation of ADM and autologous dermis mixture showed that group C had the best filling effect with the least infiltration of inflammatory cells and the highest vascular density compared to A, B, D and E groups in the study. Conclusion: When combined at the ratio of 50%:50%, the autologous dermis combined and acellular dermal matrix showed better performance compared to the other four different ratios in this study. This implies that this combination is potentially safer, effective and stable as a filling material compared to ADM or dermal matrix alone. No Level Assigned: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266. [ABSTRACT FROM AUTHOR]

Non-surgical endodontic retreatment is a reliable conservative option for managing post-treatment apical periodontitis. However, effective microbial control, based on the maximization of filling removal and disinfection protocols, is not yet predictable. Traditional gutta-percha solvents, which are indistinctively used for both the core and sealer filling materials, became obsolete due to unprecedented advances in endodontic technology. Nonetheless, microtomography, scanning electronic microscopy findings, and histobacteriological analysis tend to confirm the persistence of filling materials and the lack of association between root canal enlargement and superior disinfection. There is a controversy regarding the most suitable clinical protocols surrounding the shaping procedures and the supplementary disinfection steps. Based on the literature and the previous work of the team, the authors aimed to summarize the current knowledge regarding specific solvent formulations that target filling materials. Additionally, the advantage of an additional irrigation step to optimize disinfection was highlighted. This adjunctive procedure serves a dual role in the dissolution of filling materials, and in conferring an antibiofilm effect. Further research is needed to understand the novel contribution of these strategies upon clinical practice outcomes.

Background: Restorative dentistry aims to reproduce natural tooth shades through resin composites that must be layered to obtain colors, opacities, and translucencies, and therefore, clinical success is operator skill dependent., Aims: The purpose of this study is to evaluate the color shift of single-shade composite restorations before and after dental bleaching., Materials and Methods: Eighty human extracted posterior teeth were restored with four single-shade composites (Omnichroma OM; Clearfil Majesty ES-2 Universal CL; Essentia Universal ES; Venus Diamond One VE) ( n = 20 each). Standardized V class cavities were prepared on buccal side. VITA Easyshade V spectrophotometer was used to register VITA color and color coordinates 24 h before (T 0 ), 24 h after (T 1 ), and 1 week after (T 2 ) dental bleaching (Opalescence Boost PF 40%). Color differences (ΔE ab ) and (ΔWI D ) were calculated and subjected to statistical analysis., Statistical Analysis: Categorical variables were analyzed using Pearson Chi-square, and data from color coordinates were analyzed using one-way analysis of variance and Tukey's multiple comparison test with Bonferroni correction. Paired t -tests were performed to compare continuous measures between groups and treatment time., Results: Instrumental evaluations revealed statistically significant differences between materials ( P < 0.05) with lower values for ES and VE samples followed by CL and OM at T 0 and T 1 . At T 2 , OM and CL ΔE ab values decrease getting closer to ES and VE., Conclusion: Single-shade composites seem to match with the surrounding bleached tooth., Competing Interests: There are no conflicts of interest., (Copyright: © 2024 Journal of Conservative Dentistry and Endodontics.)

By means of literature and market investigation, the species of materials for filling the pore with different size in concrete are analyzed in detail. The influence mechanism of the filling material on the properties of the concrete was analyzed. By surveying the range of the particle diameter, the kinds of materials which can filling in capillary pores between 100nm and 1000 nm and pores bigger than 1000 nm have been put forward. The results shows that the capillary pores with diameter from 100 nm to 1000nm can be filled with silicon powder, zeolite powder, silicon nitride powder and limestone powder with micro fine grade. Pores with diameter over 5 micrometer can be filled with ardealite powder and limestone powder with micro grade. Pores with diameter over 15 micrometer can be filled with fly ash and slag. All of the harmful pores with diameter over 1000 nm can be filled with nanometer size silicon powder, zeolite powder and limestone powder with fine grade. [ABSTRACT FROM AUTHOR]

Background: Achieving a void‐free root canal filling is a challenge in current clinical pulpectomy practice. Aim: To compare filling effectiveness and internal voids of root filling materials and obturation techniques in resin‐prototyped primary incisors by micro‐CT. Design: Fifty prototypes were instrumented and randomly divided (n = 10) according to the filling materials (Vitapex®, ZOE, Calcicur®, Feapex, and Calen®‐ZO) and obturation technique: lentulo or pressure syringe (n = 5). The specimens were micro‐CT scanned (pixel size = 7.83 μm) and reconstructed, and the total volume of filled canal (%FC) and internal voids (%IV) of the bulk filling material was calculated. Kruskal‐Wallis and Mann‐Whitney tests were used to detect differences and interactions among groups. Results: Calen®‐ZO, Vitapex®, and ZOE showed similar %FC. Calcicur® showed lower %FC compared with Calen®‐ZO, Vitapex®, and ZOE (P <.05) but similar to Feapex. No statistically significant differences in %FC between lentulo or pressure syringe were disclosed. Regarding %IV, Vitapex®, and Calen®‐ZO performed better with syringe, although Calcicur® was better with lentulo. The number of voids in the obturation bulk was similar among materials, but always lower (P <.05) in syringe filled specimens. Conclusion: Vitapex®, Calen®‐ZO, and ZOE outperformed Calcicur® and Feapex in %FC and if the syringe technique is used, %IV of the obturation bulk and presence of defects was lower. [ABSTRACT FROM AUTHOR]

Aim: This study sought to evaluate the amount of apical debris extrusion during the removal of filling material (RFM) performed by the ProTaper-Retreatment (ProTaper-R), Mtwo-Retreatment (Mtwo-R), Reciproc, and hand files. Materials and Methods: Sixty lower premolars were prepared using the ProTaper Universal system and filled with thermoplastic technique. Subsequently, the samples were randomly divided into four groups (n = 15) according to the system used for the removal of the filling material: Mtwo-R (R25/.05); ProTaper-R (D1, D2, and D3); Reciproc (R25); and hand file (type K and Hedstroem stainless steel files). The apical debris extrusion was evaluated before and after the RFM from the root canal by weighing Eppendorf tubes on a high-precision balance. Statistical analysis was performed using the ANOVA test followed by the Tukey's test (P < 0.05). Results: All of the systems produced apical debris extrusion; however, the Mtwo-R group demonstrated significantly more extrusion as compared with the ProTaper-R and Reciproc groups (P < 0.05). There was no statistically significant difference between the Reciproc, ProTaper-R, and hand file groups (P > 0.05). Conclusions: The Mtwo-R group produced significantly more extrusion than did the ProTaper-R and Reciproc groups. There was no difference between the Reciproc, ProTaper-R, and hand file groups. [ABSTRACT FROM AUTHOR]

Raw ores are mixed with filling materials during mining, which makes it difficult to sort copper‑sulfur resources. Inductively coupled plasma analysis revealed that the primary dissolved metal ions from the filling materials were Ca2+ and Fe3+. Flotation solution chemistry, flotation tests, and X-ray photoelectron spectroscopy measurements confirmed that the dissolved calcium and iron materials were adsorbed onto the chalcopyrite surface in different component forms, which reduced chalcopyrite recovery. Moreover, zeta potential measurements, turbidity analysis, microscope observation, scanning electron microscopy detection, adsorption capacity measurements, and contact angle measurements revealed that the dissolved anions and cations from filling materials can change the surface zeta potential of chalcopyrite and filling materials, weaken the mutual repulsion energy, and strengthen the aggregation effect, thus reducing the adsorption of butyl xanthate on the chalcopyrite surface and its surface hydrophobics. The chalcopyrite recovery eventually decreased from 96.41% to 86.63%. [Display omitted] • The effect of filling materials on chalcopyrite flotation was firstly discussed. • The dissolved metal ions can be adsorbed on the surface of chalcopyrite in the form of hydrophilic hydroxide. • The dissolved materials can strengthen the aggregation between filling materials and chalcopyrite. • The addition of filling materials can weaken the flotation recovery of chalcopyrite. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the shear bond strength of different sealant and filling materials, used in minimally invasive dentistry, to human enamel.Materials and Methods: Thirty-five sound extracted third molars were selected. The crowns were longitudinally sectioned, embedded in polystyrene resin, and grounded until a flat enamel surface was reached. The samples were assigned into seven groups (n = 10), according to the materials: G1-Fluoroshield; G2-Clinpro; G3-Dyract AP; G4-F2000; G5-Vitremer; G6-Fuji IX; G7-Vidrion F. All materials were applied according to the manufacturer's instructions. The samples were stored in distilled water at 37 degrees C for 24 h and submitted to a shear bonding strength test in a universal testing machine with a crosshead speed of 0.5 mm/min. The failure sites were observed in Scanning Electron Microscopy (SEM). The data were submitted to ANOVA and Tukey's tests (p < 0.05).Results: The mean values (MPa) of shear bond strength were for Fluroshield (25.92 +/- 8.83), Vitremer (20.41 +/- 13.34), Dyract AP (17.08 +/- 6.38), Clinpro (12.82 +/- 8.38), F2000 (8.71 +/- 3.74), Fuji IX (7.64 +/- 2.57), and Vidrion F (4.54 +/- 2.11). Fluroshield resin sealant and Vitremer resin modified glass-ionomer showed statistically higher shear bond strength values than the conventional glass ionomer (GIC) cements. Clinpro and F2000 showed bond strength values with statistical difference only from Fluroshield. The failure mode varied among the groups. The majority of samples presented mixed failure.Conclusion: FluroShield and Vitremer showed better performance of shear bond strength to enamel than conventional GIC. [ABSTRACT FROM AUTHOR]

This paper is a literature review with additional virtual analyses of the authors’ own experimental research results. Knowledge from various areas was synergistically combined, appropriately for concurrent engineering, presenting several possible methodological approaches used in research, optimizing the selection of engineering materials and the conditions of their application with particular application in endodontics. Particular attention was paid to the theoretical aspects of filling material strengths, weaknesses, opportunities, and threats SWOT analysis. Attention was paid to the original concepts of Sustainable Dentistry Development in conjunction with Dentistry 4.0, which includes endodontics as an important element. The dentists’ actions, among others, in conservative dentistry, along with endodontics, requires close cooperation with engineers and the enginering sciences. Methods of root canal preparation were described, together with selected tools, including those made of nitinol. Principles concerning the process of cleaning and shaping the pulp complex are presented. The importance of obturation methods, including the Thermo-Hydraulic-Condensation THC technique, and the selection of filling materials with the necessary sealants for the success of endodontic treatment are discussed. The experimental studies were carried out in vitro on human teeth removed for medical reasons, except for caries, for which two groups of 16 teeth were separated. After the root canal was prepared, it was filled with studs and pellets of a filling material based on polyester materials, which has gained the common trade name of resilon or, less frequently, RealSeal (SybronEndo) with an epiphany sealant. The teeth for the first group were obturated by cold lateral condensation. In the second case the obturation was performed using the Thermo-Hydraulic-Condensation technique using System B and Obtura III. The experimental leakage testing was done using a scanning electron microscope SEM and a light stereoscopic microscope LSM, as typical research tools used in materialography. The research results, in a confrontation with the data taken from the literature studies, do not indicate the domination of resilon in endodontics.

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Cellulose-based nanocomposites have gained much attention due to their remarkable biological properties such as biodegradability, biocompatibility, and low toxicity. In this research work, 1-h-3-methylimidazolium hydrogen sulfate ionic liquid was employed as an efficient solvent for preparation of cellulosic Ag-nanocomposites (CRC/AgNPs composite) from Neem plant. Ionic liquid plays a dual role in obtaining cellulose-rich compound (CRC; removing lignin and hemicellulose components) and plant's extract (phenolic compounds such as flavonoids, tannins, etc.) that reduces the AgNO3 into AgNPs for preparation of CRC/AgNPs composite. The prepared CRC/AgNPs composite was characterized using XRD, FTIR and SEM techniques. The XRD and FTIR spectral analysis showed the characteristic peaks assigned to cellulosic constituent and AgNPs. SEM analysis revealed the particles in the range from 26 to 56 nm. The CRC/AgNPs composite was evaluated for its antibacterial and mechanical properties. The antibacterial activity against S. aureus and E. coli for CRC/AgNPs composite was observed in comparison to CRC. Cell viability and morphology were performed on MC3T3-E1 cells which showed no as such toxicity for the prepared CRC/AgNPs composite. Moreover, the addition of CRC/AgNPs composite as a filler increased the compression strength of polymeric materials. [ABSTRACT FROM AUTHOR]

The gradation properties of earth-rock dam-filling materials primarily influence their mechanical properties after compaction. Herein, combined with the characteristics of rockfill gradation detection (RGD) requirements in practical engineering, an intelligent detection method for rockfill gradation based on video image (VI) recognition technology is proposed and applied to engineering applications. By designing a device for VI recording, multi-group RGD tests are conducted. Further, a method for rockfill identification and particle size gradation transformation based on VI is proposed. The accuracy and error of the RGD in traditional screening and VI recognition method are compared and analyzed. The results of the laboratory tests and engineering applications in a construction site reveal that the proposed RGD method is highly efficient, precise, and robust. • A special rockfill video image (VI) recording device is designed. • An intelligent control model for the VI recording parameters is developed. • A systematic and comprehensive RGD method based on VI recognition is proposed. [ABSTRACT FROM AUTHOR]

To study the impact of acid environment on the water-rich filling materials, experimental methods including intensity detection, scanning electron microscopy and X-ray diffraction were used to analyze the macro and micro changes of water-rich filling materials in acid environment and to discuss the corrosion and deterioration mechanism. After soaking for 180 d in hydrochloric solu-tions of pH 1 and pH 3, the compressive strength of the materials decreases by 88.8% and 58%, respectively, compared with that of standard curing for 28 d. After soaking in a sulfuric acid solution of pH 3, the compressive strength decreases by 68%. When the ma-terials were soaked in a sulfuric acid solution of pH 1, the compressive strength is zero. Microscopic tests show that dihydrate gypsum is generated in the materials with the prolongation of immersion time in the sulfuric acid solution. In the hydrochloric acid solution, di-hydrate gypsum is produced only in the solution of pH 1 after soaking for 180 d. The corrosion of the hydrochloric acid solution on the materials is mainly the dissolution corrosion of hardened structure with the neutralization effect of H+. The corrosion of the sulfuric acid solution on the materials is the dissolution corrosion of hardened structure with the neutralization effect of H+ and the expansion corrosion of dihydrate gypsum. The corrosive action of the sulfuric acid solution on the materials is stronger than that of the hydrochlo-ric acid solution.

In order to investigate the characteristics of deformation and water loss of hardened paste of water-rich filling material under aging effect,the creep property of water-rich filling materials with a certain mass ratio of water to solid was studied in different stress conditions. The deformation characteristics,water loss and its relationship with external load on the filling body in the process of creep were analyzed by using scanning electron microscopy and differential thermal analysis-thermal gravimetry(DTA-TG). It is found that the instability and failure critical stress of water-rich filling materials with a 2.0 water-to-solid mass ratio is 1.96 MPa,which is 90% of their compressive strength. Creep cannot affect the content of combined water in water-rich filling materials. But unbound water in water-rich filling materials can run off when instability and failure happen. The relative loss value of unbound water content is of linear positive correlation with the external load level. The loss of unbound water can induce more interspaces in waterrich filling materials. These cracks are quickly pressed and the hardening body produces large deformation under the external load,which leads to the local instability of the filling body and thus affects the overall stability of the goaf.

As for the problem that different gypsum types have different influence on the condensation performance of water-rich filling materials,micro experiments,such as X-ray diffraction,scanning electron microscopy and infrared spectroscopy,were used to analyze the composition of the hardened body and investigate the influence of dihydrate gypsum and hemihydrate gypsum on the setting and hardening characteristics of water-rich filling materials. It is found that in a water-rich filling material system of sulphoaluminate cement-gypsum-lime,the gypsum type should be dihydrate gypsum so as to ensure the normal condensation setting and hardening; if hemihydrate gypsum is used as a raw material,the water-rich filling material has not strength after hydrating for 7 d. When dihydrate gypsum is adequate,the generated ettringite crystals are fine needle-like; but when dihydrate gypsum is inadequate,the generated ettringite crystals are short hexagonal columnar. The strength of the water-rich filling material is mainly derived from ettringite generated by the reaction of sulphoaluminate cement gypsum and lime,rather than the hydration products of cement generated by itself such as hydration calcium sulphoaluminate,alumina gel and calcium hydroxide.

The surface stockpiling of phosphogypsum not only occupies a large amount of land, but also seriously harms the surrounding ecological environment. The preparation of phosphogypsum into filling materials for mine filling can not only maintain the stability of surrounding rock, reduce surface subsidence, enhance the recovery of resources, but it can also completely solve the problem of phosphogypsum stockpiling. Under certain activation conditions, hemihydrate phosphogypsum has a strong cementing property. It is an important way to reduce the filling cost by using hemihydrate phosphogypsum instead of cement as a cementing material. Through laboratory experiments, the filling materials based on hemihydrate phosphogypsum were developed. In order to further verify its feasibility in practical filling engineering, the industrial experiment of goaf filling was carried out in a phosphorus mine. The results show that the filling system was simple, reliable, and easy to operate and manage. The strength of the filling body basically reached the expected strength target of 2.5 MPa in 3 days. The consolidation speed of the filling materials was faster, which is beneficial to the safe underground construction of the mine. The results of the industrial experiment of goaf filling indicate that the filling materials based on hemihydrate phosphogypsum are suitable for mine filling engineering practice, the work amount is small, and the filling cost is low.