• Title/Summary/Keyword: white cement

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The Optimal Composition Range of the EVA Powder for Resistance Wheel moving Load of Cement Mortar-Type Surface Finishing Material for Parking Slab (시멘트 모르타르계 주차장 바닥 마감재의 윤하중 저항성능을 위한 EVA 분말수지의 최적 첨가 범위에 관한 실험적 연구)

  • Shao, Xu-Dong;Kwak, Kyu-Sung;Chae, Woo-Byung;Bae, Kee-Sun;Oh, Sang-Keun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2010.05a
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    • pp.67-70
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    • 2010
  • This study investigates the physical properties of the acrylic emulsion mortar according to variable composition set of redispersible emulsion powders. This materials have to be composed of many types of binders and chemical additives. So it is difficult to decide suitable mixing proportion of composition materials. The redispersible emulsion powders using "2, 4, 6, 8kg" of EVA polymers dispersion ranges are prepared with acrylic emulsion mortars and were tested for basic characteristics such as flexural, and compressive strength, wheel load. Through experiments we found that the improved formula to satisfy the standard of wheel load by EVA polymers, and the masration rangs between about 2.0% to 2.6% which the white portland cenmet and EVA polymers is good for resistauce wheel load.

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Evaluation of Humidity Control Ceramic Paint Using Gypsum Binder

  • Lee, Jong-Kyu;Kim, Tae-Yeon
    • Journal of the Korean Ceramic Society
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    • v.55 no.1
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    • pp.74-79
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    • 2018
  • Active clay, bentonite and zeolite were used as porous materials for humidity controlling ceramic boards. The specific area and the pore volume of active clay were higher than those of bentonite and zeolite. It was effective to add white cement as well as a retarding agent to control the setting time of the ceramic paint. As the amount of added porous materials increases, the specific surface area and total pore volume of ceramic paint increase, but the average pore diameter decreases. The addition of porous materials having a high specific area and a large pore volume improves the moisture absorptive and desorptive performance of the ceramic paint. Therefore, in this experiment, the moisture absorptive and desorptive properties were best when active clay was added. Also, as the added amount of porous materials increases, the moisture absorptive and desorptive properties improve. In this experiment, when 70 mass% of active clay was added to ceramic paint, the hygroscopicity was highest at about $80g/m^2$.

Petrological and Geological Safety Diagnosis of Multi-storied Stone Pagoda in the Daewonsa Temple, Sancheong, Korea (대원사 다층석탑의 지질학적 및 암석학적 안전진단)

  • 이찬희;서만철
    • Economic and Environmental Geology
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    • v.35 no.4
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    • pp.355-368
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    • 2002
  • The multi-storied Daewonsa stone pagoda (Treasure No. 1112) in the Sancheong, Korea was studied on the basis of deterioration and geological safety diagnosis. The stone pagoda is composed mainly of granitic gneiss, partly fine-grained granitic gneiss, leucocratic gneiss, biotite granite and ceramics. Each rock of the pagoda is highly exfoliated and fractured along the edges. Some fractures in the main body and roof stones are treated by cement mortar. This pagoda is strongly covered with yellowish to reddish brown tarnish due to the amorphous precipitates of iron hydroxides. Dark grey crust by manganese hydroxides occur Partly, and some Part coated with white grey gypsum and calcite aggregates from the reaction of cement mortar and rain. As the main body, roof and upper part of the pagoda, the rocks are developed into the radial and linear cracks. Surface of this pagoda shows partly yellowish brown, blue and green patchs because of contamination by algae, lichen, moss and bracken. Besides, wall-rocks of the Daewonsa temple and rock aggregates in the Daewonsa valley are changed reddish brown color with the same as those of the pagoda color. It suggests that the rocks around the Daewonsa temple are highly in iron and manganese concentrations compared with the normal granitic gneiss which color change is natural phenomena owing to the oxidation reaction by rain or surface water with rocks. Therefore, for the attenuation of secondary contamination, whitening and reddishness, the possible conservation treatments are needed. Consisting rocks of the pagoda would be epoxy to reinforce the fracture systems for the structural stability on the basements.

Comparison of Shear Bond Strength of Different Restorative Materials to Tricalcium Silicate-Based Pulp Capping Materials (Tricalcium Silicate-Based 치수복조재에 대한 수 종 수복재의 전단결합강도 비교)

  • Jeong, Hwakyong;Lee, Nanyoung;Lee, Sangho
    • Journal of the korean academy of Pediatric Dentistry
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    • v.44 no.2
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    • pp.200-209
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    • 2017
  • The aim of this study was to evaluate the shear bond strength (SBS) of three typical restorative materials - glass ionomer cement (GIC), resin-modified glass ionomer (RMGIC) and composite resin (CR) - to different pulp capping materials, i.e., Theracal $LC^{TM}$ (TLC), $Biodentine^{TM}$ (BD), and $ProRoot^{TM}$ white MTA (WMTA). 90 acrylic blocks with a center hole were prepared. The holes were completely filled with three pulp capping materials (TLC, BD, and WMTA), with 30 specimens per capping material. The samples were then randomly divided into 3 subgroups of 10 specimens each and were overlaid with GIC, RMGIC, or CR. A total 9 specimen groups were prepared. The SBS was assessed using a universal testing machine. Kruskal-Wallis test and Mann-Whitney's test were performed to compare the SBS among the subgroups (p < 0.05). After the SBS test, the fractured surfaces were examined under a stereomicroscope at a magnification of $25{\times}$. The highest and lowest SBS values were recorded for TLC-CR and TLC-GIC, respectively. With regard to the SBS to the three pulp capping materials, CR was found to be superior to RMGIC and GIC. BD showed a higher SBS compared to TLC and WMTA when used with GIC.

Effect of different adhesive systems and post surface treatments on the push-out bond strengths of fiber-reinforced post (다양한 접착 시스템 및 포스트의 표면 처리가 섬유 강화 포스트의 접착 강도에 미치는 영향)

  • Kim, Min-Woo;Ahn, Jin-Hee;Kim, Lee-Kyoung;Shim, Hye-Won
    • The Journal of Korean Academy of Prosthodontics
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    • v.54 no.3
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    • pp.218-225
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    • 2016
  • Purpose: The purpose of this study was to evaluate the push-out bond strength of glass-fiber post cemented with different adhesive systems and surface treatments. Materials and methods: 160 tooth samples made from 48 human maxillary single-rooted teeth with similar root length were divided into 4 groups according to the adhesive system (no adhesive, Adper Single Bond 2, Clearfil SE Bond, Clearfil S3). Each group had 4 subgroups according to the post surface treatment methods (no treatment, sandblast, silane, sandblast and silane). Posts (Parapost Fiber White) were cemented with Rely X Unicem. The teeth were sectioned perpendicular to their long axis into 1-mm thick sections. The push-out tests was performed at a speed of 0.5 mm/min. The results were evaluated by 2-way ANOVA, 1-way ANOVA and multiple comparison procedures (Tukey test) (${\alpha}=0.05$). Results: Tukey test showed that the adhesive system significantly influenced the push-out strength. The Clearfil SE Bond group showed the highest value. Post surface treatments showed no significant effect. Conclusion: Bond strength of glass-fiber post cemented with self-adhesive resin cement using Clearfil SE Bond showed significantly higher values compared to other adhesive systems.

A Study on the Perception for Rural Housing Remodeling for Improved Residential Environment - For Rural Residents in Jeollanam-do - (거주환경 개선을 위한 농촌주택 개보수 인식에 관한 연구 - 전라남도 농촌마을 거주자를 대상으로 -)

  • Kim, Yun-Hag
    • Journal of the Korean Institute of Rural Architecture
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    • v.16 no.3
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    • pp.27-36
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    • 2014
  • The purpose of this study is to provide necessary information for the establishment of remodeling range needed first to support the future remodeling of rural housing. For this, this study examined landscape characteristics of rural housing such as an outer wall, a roof, a fence, and a gate which are main elements of forming the landscape of a rural village and rural residents' perception for remodeling. The results were as follows. The subject rural housing mostly had a timber structure and a masonry structure. Common roof types were a hip-and-gable roof and a gable roof. Frequent materials were a panel, a tile, and slate and common colors were primary colors such as reddish brown, black, and gray. A fence made of cement blocks and finished by a white paint was often found. A closed gate with iron frames was common. A standup kitchen and a flush toilet inside the house were common. The family members of rural residents were mostly two including a farmer husband and his wife. Elderly people of sixty and over were the most common. For residential environment satisfaction, a half of respondents were not unsatisfied with residential environment mostly due to an old house. Most respondents who were not satisfied with residential environment had high perception for the need of remodeling. The most commonly asked remodeling part was a roof, followed by a toilet, and an outer wall, indicating that the need of exterior remodeling was higher than that of interior remodeling. For a remodeling method, a total improvement was preferred. Although some rural village housing was improved by support of the government, local governments, or social groups, there are still many old houses. As this co-existence of improved houses and old houses hinders the landscape of rural village, it is necessary to give a support. But rural residents' requests should be first actively reflected to establish a guideline of supporting rural house remodeling.

Weathering Phenomena of the Rocks Constituting the Seoggulam (석굴암을 이루는 암석의 풍화현상)

  • Lee, Sang Hun
    • Journal of Conservation Science
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    • v.8 no.1 s.11
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    • pp.1-9
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    • 1999
  • The present aspect of the Seoggulam is the result of natural weathering of the rocks and influences by mankind. The rocks constituting the Seoggulam is granodiorite of medium and coarse grains which show brown to dark brown weathered surface resulted mainly from chemical weathering of feldspars. It also shows partly milky white or black colors due to influences by weathering products of cement used in the concrete dome and cracks. There are cracks and crack zones with very small cracks which may be formed by strong weathering and influences of shocks during operations of reconstitution and repair. However, for the better conservation, it must be considered to maintain the balances of temperature and moisture, especially relative moisture in places within the room, structural stability, and the influences of vibration made up by some reasons.

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Do conventional glass ionomer cements release more fluoride than resin-modified glass ionomer cements?

  • Cabral, Maria Fernanda Costa;Martinho, Roberto Luiz de Menezes;Guedes-Neto, Manoel Valcacio;Rebelo, Maria Augusta Bessa;Pontes, Danielson Guedes;Cohen-Carneiro, Flavia
    • Restorative Dentistry and Endodontics
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    • v.40 no.3
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    • pp.209-215
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    • 2015
  • Objectives: The aim of this study was to evaluate the fluoride release of conventional glass ionomer cements (GICs) and resin-modified GICs. Materials and Methods: The cements were grouped as follows: G1 (Vidrion R, SS White), G2 (Vitro Fil, DFL), G3 (Vitro Molar, DFL), G4 (Bioglass R, Biodinamica), and G5 (Ketac Fil, 3M ESPE), as conventional GICs, and G6 (Vitremer, 3M ESPE), G7 (Vitro Fil LC, DFL), and G8 (Resiglass, Biodinamica) as resin-modified GICs. Six specimens (8.60 mm in diameter; 1.65 mm in thickness) of each material were prepared using a stainless steel mold. The specimens were immersed in a demineralizing solution (pH 4.3) for 6 hr and a remineralizing solution (pH 7.0) for 18 hr a day. The fluoride ions were measured for 15 days. Analysis of variance (ANOVA) and Tukey's test with 5% significance were applied. Results: The highest amounts of fluoride release were found during the first 24 hr for all cements, decreasing abruptly on day 2, and reaching gradually decreasing levels on day 7. Based on these results, the decreasing scale of fluoride release was as follows: G2 > G3 > G8 = G4 = G7 > G6 = G1 > G5 (p < 0.05). Conclusions: There were wide variations among the materials in terms of the cumulative amount of fluoride ion released, and the amount of fluoride release could not be attributed to the category of cement, that is, conventional GICs or resin-modified GICs.

Effects of the exposure site on histological pulpal responses after direct capping with 2 calcium-silicate based cements in a rat model

  • Trongkij, Panruethai;Sutimuntanakul, Supachai;Lapthanasupkul, Puangwan;Chaimanakarn, Chitpol;Wong, Rebecca;Banomyong, Danuchit
    • Restorative Dentistry and Endodontics
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    • v.43 no.4
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    • pp.36.1-36.12
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    • 2018
  • Objectives: Direct pulp capping is a treatment for mechanically exposed pulp in which a biocompatible capping material is used to preserve pulpal vitality. Biocompatibility tests in animal studies have used a variety of experimental protocols, particularly with regard to the exposure site. In this study, pulp exposure on the occlusal and mesial surfaces of molar teeth was investigated in a rat model. Materials and Methods: A total of 58 maxillary first molars of Wistar rats were used. Forty molars were mechanically exposed and randomly assigned according to 3 factors: 1) the exposure site (occlusal or mesial), 2) the pulp-capping material (ProRoot White MTA or Bio-MA), and 3) 2 follow-up periods (1 day or 7 days) (n = 5 each). The pulp of 6 intact molars served as negative controls. The pulp of 12 molars was exposed without a capping material (n = 3 per exposure site for each period) and served as positive controls. Inflammatory cell infiltration and reparative dentin formation were histologically evaluated at 1 and 7 days using grading scores. Results: At 1 day, localized mild inflammation was detected in most teeth in all experimental groups. At 7 days, continuous/discontinuous calcified bridges were formed at exposure sites with no or few inflammatory cells. No significant differences in pulpal response according to the exposure site or calcium-silicate cement were observed. Conclusions: The location of the exposure site had no effect on rat pulpal healing. However, mesial exposures could be performed easily, with more consistent results. The pulpal responses were not significantly different between the 2 capping materials.

Effect of intracanal medications on the interfacial properties of reparative cements

  • Pereira, Andrea Cardoso;Pallone, Mariana Valerio;Marciano, Marina Angelica;Cortellazzi, Karine Laura;Frozoni, Marcos;Gomes, Brenda P.F.A.;de Almeida, Jose Flavio Affonso;de Jesus Soares, Adriana
    • Restorative Dentistry and Endodontics
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    • v.44 no.2
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    • pp.21.1-21.8
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    • 2019
  • Objectives: The purpose of the present study was to evaluate the effect of calcium hydroxide with 2% chlorhexidine gel (HCX) or distilled water (HCA) compared to triple antibiotic paste (TAP) on push-out bond strength and the cement/dentin interface in canals sealed with White MTA Angelus (WMTA) or Biodentine (BD). Materials and Methods: A total of 70 extracted human lower premolars were endodontically prepared and randomly divided into 4 groups according to the intracanal medication, as follows: group 1, HCX; group 2, TAP; group 3, HCA; and group 4, control (without intracanal medication). After 7 days, the medications were removed and the cervical third of the specimens was sectioned into five 1-mm sections. The sections were then sealed with WMTA or BD as a reparative material. After 7 days in 100% humidity, a push-out bond strength test was performed. Elemental analysis was performed at the interface, using energy-dispersive spectroscopy. The data were statistically analyzed using analysis of variance and the Tukey test (p < 0.05). Results: BD presented a higher bond strength than WMTA (p < 0.05). BD or WMTA in canals treated with calcium hydroxide intracanal medications had the highest bond strength values, with a statistically significant difference compared to TAP in the WMTA group (p < 0.05). There were small amounts of phosphorus in samples exposed to triple antibiotic paste, regardless of the coronal sealing. Conclusions: The use of intracanal medications did not affect the bond strength of WMTA and BD, except when TAP was used with WMTA.